Molecular Cell Test 1

T/F: Acetylation of the N terminal tail of histone H3 is important for transcriptional repression.

False

T/F: The sequence TATAA is recognized by a basic helix-loop-helix protein and is necessary to activate transcription.

False

T/F: Like bacterial repressors, eukaryotic gene expression proteins act by directly competing with the RNA polymerase for access to the DNA.

False

T/F: Most gene regulatory proteins in prokaryotes can act even when they are bound to DNA thousands of nucleotide pairs away from the promoter that they influence.

False

T/F: Unlike eukaryotes, which use three different RNA polymerases, prokaryotes use only one type of core RNA polymerase molecule but modify it with different sigma subunits.

True

T/F: Each time the genome is replicated, half the newly synthesized DNA is stitched together from Okazaki fragments.

True

T/F: Zinc fingers and leucine zippers are amino acid motifs found in transcriptional activators.

True

T/F: DNA repair enzymes that correct damage introduced by deamination and deprivation must preferentially recognize such defects on newly synthesized DNA strands.

False

You are studying two strands of DNA. They have exactly the same length but the first one has a very high G +C/A + T ratio of 3.4. The second DNA strand has a G+ C/A +T ratio of 2.3. Which of the two strands will have the lowest melting temperature and why

d. the second strand because it contains fewer H bonds

During homologous recombination, the resolution of the Holliday structures is important because:
a. can regenerate the parental chromosome
b. can generate recombinant chromosomes
c. can result in repair of double strand breaks
d. a and c
e. a,b, and c

e. a,b, and c

Which of the following are enzymes that play a key role in the base excision repair of nucleotide mismatches and damaged bases?
a. topoisomerases
b. glycosidases
c. glycosylases
d. depurinases
e. deaminases

c. glycosylases

What statement below explains the uniform width of the DNA molecule along its entire width?
a. A purine nitrogenous base always pairs with another purine nitrogenous base
b. A pyrimidine nitrogenous base always pairs with another pyrimidine nitrogenous ba

c. A pyrimidine nitrogenous base always pairs with a purine nitrogenous base

____________ refers to the fact that the sequence of one DNA strand specifies the sequence of the other strand in the double helix?
a. Indirectionality
b. Complexity
c. Complementarity
d. Similarity
e. Compulsivity

c. Complementarity

In order to clone a gene mammalian gene by complementation of a yeast temperature-sensitive mutation you would use:
a. a genomic library
b. PCR
c. a cDNA library
d. either a or c
e. none of the above

c. a cDNA library

DNA replicating enzymes are known to have trouble copying genome regions that contain which class of DNA sequences? These stretches of DNA change in length through the generations and due to their variable lengths within the population, they have been use

c. microsatellite DNAs

Which of the following lead(s) to a point mutation?
a. deamination of a cytosine base into a uracil base
b. benzo(a)pyrene conversion of guanine to a thymine base
c. deamination of 5-methyl cytosine into thymine
d. a and b
e. a,b, and c

e. a,b, and c

An enzyme that breaks DNA, dispels the tension, and reseals the strand ahead of a DNA replication growing fork is called a(n)?
a. topoisomerase
b. DNA polymerase
c. phosphodiesterase
d. aminoacyl-tRNA synthetase
e. helicase

a. topoisomerase

The base in the wobble position of a codon
a. is the 5' (first) base
b. is the 3' (third) base
c. is the second base
d. often contains adenine
e. often contains inosine

b. is the 3' (third) base

What method can be used to functionally inactivate a gene without altering its sequence?
a. gene knockout
b. RNA interference
c. dominant negative mutation
d. b and c
e. all of the above

d. b and c

What happens if naked DNA is moderately treated with nonspecific nucleases?
a. DNA is broken down into a population of fragments with a random size distribution
b. Most DNA is converted into fragments that are about 200 (or multiples of 200) bp long.
c. D

a. DNA is broken down into a population of fragments with a random size distribution

Most eukaryotic genes are controlled at the level of:
a. transcription initiation
b. transcription elongation
c. transcription termination
d. translation initiation

a. transcription initiation

What is the function of TFIIH in the transcription initiation complex?
a. binding to the TATA box
b. unwinding the DNA duplex
c. catalyzing the synthesis of RNA
d. a and b
e. a,b, and c

b. unwinding the DNA duplex

What difference has been detected between histone H3 in heterochromatic and euchromatic regions that appears to be connected with the initiation of heterochromitzation?
a. the position #9 lysine is methylated in heterochromatin and unmethylated or acetyla

a. the position #9 lysine is methylated in heterochromatin and unmethylated or acetylated in euchromatin

Which the of DNA repair removes the part of the strand having certain types of bulky lesions, like pyrimidine dimers and nucleotides to which various chemical groups?
a. nucleotide excision repair
b. base excision repair
c. mismatch repair
d. double-stran

a. nucleotide excision repair

The most damaging DNA lesions are:
a. double-strand breaks
b. thymine-thymine dimers
c. deamination of 5-methl C
d. depurination
e. disincorporation of nucleotides during DNA replication

a. double-strand breaks

Cultured mammalian cells grown in thymidine for many generations were allowed to undergo replication in the presence of bromodeoxyuridine (BrdU), which replaces thymidine in DNA. After one round of replication, what would the DNA look like if replication

c. Half of the chromatids have two strands that contain BrdU and half of the chromatids have 2 strands lacking BrdU

In a reticulocyte lysate the polynucleotide 5'-AUGUUUUUUUUUUUUUUU directs the synthesis of Met-Phe-Phe-Phe-Phe. In the presence of farsomycin, a new antibiotic being developed, this polymer directs synthesis of Met-Phe only. From this information, which o

d. It blocks translocation of peptidyl-tRNA from the A site to the P site of the ribosome

What technique supplied the data that led Watson and Crick to the double helical structure of DNA?
a. sucrose density centrifugation
b. polyacrylamide gel electrophoresis
c. x-ray diffraction/crystallography
d. autoradiography
e. ion exchange chromatograp

c. x-ray diffraction/crystallography

The initiator tRNA (Met-tRNAi^Met) binds to the ________ site of the _____S ribosome.

1. P
2. 40

The __________ is the region where __________ binds to the DNA prior to the beginning of transcription.

1. promoter
2. RNA polymerase II

The __________ gene is commonly used as a _______ to study promoter sequences and their effect in transcription.

1. lacZ
2. reporter

The __________ linkage is the distinguishing chemical feature of the 5' methylated cap on eukaryotic mRNA.

5'-5'

Replication moves out from the origin in ___________ directions and is said to be _____________.

1. opposite
2. bidirectional

After exonucleases have excised the damaged portion of DNA, how can DNA polymerase fill in the gap? Is there a primer?

The DNA polymerase is recruited to the damaged region and fills the gap extending from the 3' hydroxyl group of the previous nucleotide. Thus, the last nucleotide of the preceding double stranded region serves as the primer for the polymerase.

Which parts of the newly synthesized mRNA molecule do not transmit information for the synthesis of protein?

5' cap, 5' UTR, introns, 3' UTR, and polyA tail

If perfect Watson-Crick base pairing were demanded between codons and anticodons, cells would need 61 different tRNAs. Since there are only 20 amino acids used in protein synthesis, how would you explain this excess number of tRNAs compared to amino acids

There is redundancy or degeneracy of the code; several codons code for the same amino acid. Cells have fewer than 61 tRNAs because of the "wobble" effect, in which some tRNAs recognize different codons that code for the same amino acid, minimizing the nee

/What is the main function of eIF4E during translation? What would happen if GTP cannot be hydrolyzed?

The eIF4E subunit of the eIF4 complex binds the 5' cap structure of mRNAs and then associates with the pre initiation complex, to form the initiation complex. Lack of GTP hydrolysis would inhibit formation of the pre initiation complex, translation would

What enzymatic activities do DNA polymerases have?

DNA synthesis from template strand and proofreading activity

What was probably the first carrier of genetic information in primitive organisms?
a. DNA that could self-replicate
b. proteins
c. polypeptides
d. RNA that could self-replicate

d. RNA that could self-replicate

Who was the first to suggest semiconservative replication?
a. Meselson and Stahl
b. Hershey and Chase
c. Watson and Crick
d. Avery, McCarty and MacLeod
e. Darwin and Wallace

c. Watson and Crick

Which type of replication results in 2 duplexes made of one parental strand and one newly synthesized strand? a. semiconservative replication
b. conservative replication
c. dispersive replication
d. incisive replication
e. reservative replication

a. semiconservative replication

What type of replication results in the integrity of both parental strands being disrupted? The new duplex strands are made of both old and new DNA. Neither the parental strands nor the parental duplex is preserved.
a. semiconservative replication
b. cons

c. dispersive replication

Bacteria are grown in a medium containing 15NH4Cl for a number of generations so that all of the DNA is made of fully "heavy" DNA. The bacteria are moved to a new medium and grown in 14NH4Cl so that all new DNA will be light. After one generation time, wh

c. All of the DNA is made of 1 "heavy" strand and 1 "light" strand

Bacteria are grown in a medium containing 15NH4Cl for a number of generations so that all of the DNA is made of fully "heavy" DNA. The bacteria are moved to a new medium and grown in 14NH4Cl so that all new DNA will be "light". If replication were conserv

e. 75% of the DNA is made of 2 "light" strands and 25% of the DNA is made of 2 "heavy" strands

Bacteria are grown in a medium containing 15NH4Cl for a number of generations so that all of the DNA is made of fully "heavy" DNA. The bacteria are moved to a new medium and grown in 14NH4Cl so that all new DNA will be "light". If replication were dispers

d. Each strand is made of a mixture of "heavy" and "light" DNA

Cultured mammalian cells grown in thymidine for many generations were allowed to undergo replication in the presence of bromodeoxyuridine (BrdU), which replaces thymidine in DNA. After one round of replication, what does the DNA look like?
a. All chromati

a. All chromatids have one strand that contains BrdU and one strand that contains thymidine

Cultured mammalian cells grown in thymidine for many generations were allowed to undergo replication in the presence of bromodeoxyuridine (BrdU), which replaces thymidine in DNA. After two rounds of replication, what does the DNA look like?
a. All chromat

e. Half of the chromatids have two strands that contain BrdU and half of the chromatids have 1 strand lacking BrdU and one strand containing BrdU

Cultured mammalian cells grown in thymidine for many generations were allowed to undergo replication in the presence of bromodeoxyuridine (BrdU), which replaces thymidine in DNA. After two rounds of replication, what would the DNA look like if replication

e. 75% of the chromatids have two strands that contain BrdU and 25% of the chromatids have 2 strand lacking BrdU and 1 strand containing BrdU

Cultured mammalian cells grown in thymidine for many generations were allowed to undergo replication in the presence of bromodeoxyuridine (BrdU), which replaces thymidine in DNA. After one round of replication, what would the DNA look like if replication

d. Both strands of each chromatid contain mixtures of BrdU and thymidine

The specific site on the bacterial chromosome at which replication begins is called the _________.
a. beginning
b. origin
c. initiation site
d. initiator
e. replicon

b. origin

Replication moves out from the origin in ________ directions and is said to be ________.
a. opposite, unidirectional
b. opposite, bidirectional
c. three, bidirectional
d. unique, unidirectional
e. common, bidirectional

b. opposite, bidirectional

In replicating bacterial chromosomes, where does replication terminate?
a. at the origin
b. across the circular chromosome from the origin
c. at random locations around the circle
d. one quarter of the way around the DNA circle from the origin
e. near Arn

b. across the circular chromosome from the origin

What happens to DNA (circular DNA or linear DNA that is not free to rotate) when it becomes overwound?
a. It becomes negatively supercoiled.
b. It breaks into a number of fragments.
c. It becomes positively supercoiled.
d. It stretches.
e. Its mass decrea

c. it becomes positively supercoiled

The replication fork generates _______ supercoils in the ________ portion of the DNA molecule.
a. negative, replicated
b. positive, replicated
c. neutral, unreplicated
d. positive, unreplicated
e. negative, unreplicated

d. positive, unreplicated

Where is DNA gyrase normally positioned as it changes positively supercoiled DNA into negatively supercoiled DNA in the replicating circular, bacterial chromosome? a. It is permanently located at the origin.
b. It travels along the DNA behind the replicat

c. It travels along the DNA ahead of the replication fork

What supplies the energy that drives the relief of mechanical strain by DNA gyrase?
a. condensation of ATP
b. condensation of GTP
c. hydrolysis of ATP
d. hydrolysis of GTP
e. a proton gradient

c. hydrolysis of ATP

Who was the first to purify an enzyme from bacterial extracts that could incorporate DNA precursors into a polymer?
a. Arthur Kornberg
b. James Watson
c. Francis Crick
d. Jacques Monod

a. Arthur Kornberg

What evidence convinced investigators that the original unlabeled DNA in the reaction mixture served as the template for the newly made DNA?
a. The new DNA had the same base composition as the original DNA.
b. The new DNA had a variable base composition.

a. The new DNA had the same base composition as the original DNA

Which of the following DNA molecules could serve as an effective template for DNA synthesis?
a. an intact, linear, double-stranded DNA
b. a single-stranded, circular DNA
c. a partially double-stranded DNA

c. a partially double-stranded DNA

Why is an intact, linear double helix an ineffective template for DNA polymerase?
a. It has a 3'-hydroxyl group, but lacks a template.
b. It lacks a 3'-hydroxyl group, but has a template.
c. It lacks a 3'-hydroxyl group and a template.
d. It has a 3'-hydr

a. It has a 3'-hydroxyl group, but lacks a template

Why is a single-stranded, circular DNA an ineffective template for DNA polymerase?
a. It has a 3'-hydroxyl group, but lacks a template.
b. It lacks a 3'-hydroxyl group, but has a template.
c. It lacks a 3'-hydroxyl group and a template.
d. It has a 3'-hyd

b. It lacks a 3'-hydroxyl group, but has a template

What discovery suggested the presence of other DNA polymerases in bacteria besides the Kornberg DNA polymerase enzyme?
a. Kornberg DNA polymerase mutants died.
b. Kornberg DNA polymerase mutants grew much more slowly.
c. Mutants with <1% of the normal Kor

c. Mutants with <1% of the normal Kornberg DNA polymerase enzyme activity multiplied at a normal rate

All DNA polymerases lay down nucleotides in a ______ direction and move along the template in a _______ direction.
a. 3'�>5', 5'�>3'
b. N�>C. C�>N
c. 5'�>3', 3'�>5'
d. C�>N, N�>C
e. N�>C, 5'�>3'

c. 5' -----> 3', 3' ----> 5'

Which of the following is an accurate description of the polymerization reaction leading to DNA polymerization? a. The 3'-hydroxyl group at the end of the primer executes a nucleophilic attack on the 5'-?-phosphate of the incoming nucleotide triphosphate.

a. The 3'-hydroxyl group at the end of the primer executes a nucleophilic attack on the 5'-alpha-phosphate of the incoming nucleotide triphosphate

The DNA strand growing toward the replication fork grows ______ in a 5'�>3' direction as the replication fork advances and is called the ________.
a. continuously, leading strand
b. discontinuously, lagging strand
c. continuously, lagging strand
d. discon

a. continuously, leading strand

The _______ strand fragment grows away from the replication fork toward the ___- end of the previously synthesized fragment to which it is subsequently linked. a. leading, 5'
b. lagging, 5'
c. leading, 3'
d. lagging, 3'
e. lagging, N-terminal

b. lagging, 5'

Since one strand of DNA is synthesized continuously during replication and the other is made discontinuously, replication is said to be ___________.
a. continuous
b. hemicontinuous
c. discontinuous
d. semidiscontinuous
e. semicontinuous

d. semidiscontinuous

When Okazaki incubated bacteria in [3H]-thymidine for ______ and immediately killed them, the radiolabel was found as part of ________; if the cells were incubated in labeled DNA precursor for _____, most of the incorporated radioactivity became part of _

c. a few seconds, small DNA fragments, 1 to 2 minutes, a large DNA molecule

During replication, DNA is constructed in small segments called ________ that are rapidly linked to longer pieces of DNA synthesized earlier.
a. Watson fragments
b. Tokyo fragments
c. Osaka fragments
d. Okazaki fragments
e. Ouabain fragments

d. Okazaki fragments

The enzyme that joins the small fragments of the lagging strand together into a continuous strand is called _______.
a. DNA gyrase
b. DNA ligase
c. DNA polymerase
d. primase
e. deoxyribonuclease

b. DNA ligase

Strand initiation during replication is carried out by an enzyme that makes a short RNA molecule that is used as a primer; the enzyme is a distinct type of RNA polymerase, called _______.
a. RNA gyrase
b. RNA ligase
c. ribonuclease
d. primase
e. deoxyribo

d. primase

The RNA primers that initiate replication are subsequently _____ and the resulting gap in the strand is _______ DNA and then sealed by _______.
a. filled in, removed by, DNA ligase
b. removed, filled in with, DNA ligase
c. removed, filled in with, RNA lig

b. removed, filled in with, DNA ligase

Which of the following may be a further advantage of using RNA primers during initiation of a strand in replication?
a. Using primers may decrease mistakes, since they are more likely during initiation than elongation and are thus removed when the RNA is

a. Using primers may decrease mistakes, since they are more likely during initiation than elongation and are thus removed when the RNA is replaced

_________ are DNA unwinding enzymes that unwind the DNA in a reaction using the energy from _________ to break the _______ holding the two strands together.
a. DNA helicases, ATP dehydration, disulfide linkages
b. DNA gyrases, ATP hydrolysis, H bonds
c. D

d. DNA helicases, ATP hydrolysis, H bonds

Where is the DnaB helicase first loaded onto the DNA? a. at the replication terminator site
b. at the replication origin
c. at random locations through the circular chromosome
d. at the operator
e. at the promoter

b. at the replication origin

DnaB helicases bind DNA with the help of the _____ protein and move in a _______ direction along the ________ strand template.
a. DnaC, 5'�>3', leading
b. DnaA, 5'�>3', leading
c. DnaC, 3'�>5', lagging
d. DnaC, 5'�>3', lagging
e. DnaA, 5'�>3', lagging

d. DnaC, 5'---->3' , lagging

What proteins bind selectively to single-stranded DNA and are responsible for keeping it extended and preventing it from being rewound?
a. DNA helicase
b. DNA gyrase
c. single-stranded DNA binding proteins
d. ATPase
e. DNA unwindase

c. single-stranded DNA binding proteins

In bacteria, a _________ is formed when a _________ closely associates transiently with a _______.
a. primosome, helicase, DNA polymerase
b. primosome, helicase, primase
c. ribosome, helicase, primase
d. helicosome, primosome, DNA polymerase
e. primosome,

b. primosome, helicase, primase

How does DNA polymerase III move from one site on the template to a site closer to replication fork?
a. It hitches a ride with the DNA polymerase that is moving that way along the leading strand template.
b. It hitches a ride with the DNA polymerase that

a. It hitches a ride with the DNA polymerase that is moving that way along the leading strand template

How can the replication of both DNA strands by two tethered polymerases be accomplished when the template strands run in opposite directions?
a. One of the enzymes polymerizes DNA in the 3'�>5' direction.
b. The DNA of the lagging strand loops back on its

b. The DNA of the lagging strand loops back on itself so it has same orientation as the leading strand template

As replication proceeds, the lagging strand of DNA is looped back on itself so that it has the same orientation as the leading strand template; the looped DNA repeatedly grows and shortens during lagging strand replication. This model is often referred to

c. trombone model

Which DNA polymerase in bacteria is mostly involved in DNA repair to correct damaged DNA sections and removes RNA primers at the 5' ends of Okazaki fragments, replacing them with DNA?
a. DNA polymerase I
b. DNA polymerase II
c. DNA polymerase III
d. DNA p

a. DNA polymerase I

Which DNA polymerase in bacteria has not as yet had a function assigned to it, since bacterial mutants for it have been isolated without seeming to have any evident deficiencies?
a. DNA polymerase I
b. DNA polymerase II
c. DNA polymerase III
d. DNA polyme

b. DNA polymerase II

Which DNA polymerase in bacteria acts in DNA strand formation during replication and forms part of a large complex that serves as a large replication machine?
a. DNA polymerase I
b. DNA polymerase II
c. DNA polymerase III
d. DNA polymerase IV

c. DNA polymerase III

What is the name of the noncatalytic subunit of the replisome that keeps DNA polymerase associated with the DNA template?
a. ?-pleated sheet
b. ?-helix
c. ? clamp
d. ? clamp
e. ? clamp

c. beta clamp

The DNA polymerase on the leading strand template _____________.
a. stays tethered to a single ? clamp during replication b. switches from ? clamp to ? clamp during replication c. cycles to a new ? clamp that has been assembled at an RNA primer-DNA templa

a. stays tethered to a single beta clamp during replication

The assembly of the ? clamp around the DNA requires a multisubunit _______ that is also part of the ________; part of this structure opens the ______ so that it can fit around the DNA.
a. clamp loader, replicon, ? clamp
b. clamp loader, replisome, ? clamp

b. clamp loader, replisome, beta clamp

Why did Kornberg initially think that the exonuclease activity he found in his DNA polymerase preparations was a contaminating enzyme?
a. The action of exonucleases is a lot like endonuclease. b. The action of exonucleases is so dramatically opposed to th

b. The action of exonucleases is so dramatically opposed to the activity of DNA polymerases

Where on the DNA polymerase I molecule do the 5'�>3' exonuclease, 3'�>5' exonuclease and DNA polymerase activities reside?
a. all of them on the same domain
b. the two exonucleases on one domain and the polymerase activity on another domain
c. the 5'�>3'

e. each enzyme activity on a different domain

The 5'�>3' exonuclease activity of DNA polymerase I is unusual for what reason?
a. It works very slowly.
b. It works very quickly.
c. It degrades both RNA and DNA and exonucleases typically digest one or the other.
d. It is very general and has an extreme

c. It degrades both RNA and DNA and exonucleases typically digest one or the other

What is the function of the 5'�>3' exonuclease activity of DNA polymerase I?
a. It removes mismatched nucleotides that have been incorporated by mistake.
b. It replaces mismatched nucleotides with the correctly matched nucleotides.
c. It removes the DNA p

d. It removes the RNA primer laid down by the primes at the 5' end of the Okazaki fragment

What happens simultaneous with the removal of RNA primer by the 5'�>3' exonuclease activity of DNA polymerase I?
a. The DNA double helix is unwound.
b. The gap left by the removal of the RNA primer is filled in with deoxyribonucleotides.
c. The gap left b

b. the gap left by the removal of the RNA primer is filled with deoxyribonucleotides

What is responsible for joining the last deoxyribonucleotide added during RNA primer digestion and the 5' end of the previously synthesized and adjacent DNA fragment?
a. DNA polymerase I
b. DNA polymerase III
c. DNA ligase
d. the holoenzyme
e. DNA gyrase

c. DNA ligase

What is the probability that in E. coli an incorrect nucleotide will be incorporated into DNA during replication and remain there?
a. fewer than 1 in 1 billion nucleotides
b. about 1 in 1000 nucleotides
c. fewer than 1 in about 4 million nucleotides
d. ab

a. fewer than 1 in 1 billion nucleotides

How does DNA polymerase discriminate between the insertion of correct and incorrect base pairs as DNA replication proceeds?
a. Incorrect nucleotides repel each other because of their charges.
b. Distances between atoms and bond angles give incorrect base

d. if the new base pair exhibits improper geometry (size and shape), the polymerase active site cannot adopt the conformation required for catalysis and the incorrect nucleotide is not incorporated

The DNA polymerase can incorporate the wrong nucleotide occasionally. What is the probability that the wrong nucleotide is incorporated into the growing polynucleotide chain during replication?
a. fewer than 1 in 1 billion nucleotides
b. about 1 in 1000 n

d. about 1 in 100,000 to 1,000,000 nucleotides

What is the average rate of replication in bacteria like E. coli?
a. 100 nucleotides/sec
b. 1,000 nucleotides/min
c. 1,000 nucleotides/sec
d. 10,000 nucleotides/sec
e. 100 nucleotides/min

c. 1,000 nucleotides/sec

In in vitro replication systems using cellular extracts, how can specific proteins be removed from the preparation for the purpose of analyzing how their absence adversely affects the replication process?
a. targeted denaturation by altered pH
b. targeted

c. Precipitation of the protein that is to be deleted with specific antibodies to remove it from solution

The small portions in which eukaryotic cells replicate their genomes are called _______.
a. replicants
b. replicons
c. repliants
d. replicosomes
e. tracts

b. replicons

What technique was used in the discovery of the existence in eukaryotic cells of replicons, a discovery in which single DNA molecules were shown to be replicated simultaneously at several sites along their length?
a. scanning electron microscopy
b. confoc

c. autoradiography

What evidence below suggested that the sequence of DNA was unimportant in the timing of replication?
a. The inactive, heterochromatized X chromosome in female mammals replicates late in S phase, while the active euchromatic X chromosome replicates at an e

a. the inactive, heterochromatized X chromosome in female mammals replicates late in S phase, while the active euchromatic X chromosome replicates at an earlier stage

A bidirectional replication initiation site located in the ?-globin gene cluster is deleted from the ?-globin cluster and transplanted to the ochre gene in a monkey cell, a site at which replication is not normally initiated. The altered cells are grown i

a. replication is no longer initiated in the beta-globin gene cluster, but it is initiated in the ochre gene

When the initiation site is removed from the ?-globin gene cluster, how is that section of the chromosome replicated?
a. It is not replicated.
b. A new replication initiation site is transposed to the original site of the excised replication initiation si

c. This part of the chromosome is replicated by a replication fork that moves into the region from an unidentified origin outside the beta-globin cluster

What binds to the ORC to assemble the prereplication complex that is competent to initiate replication?
a. the ORC factors
b. licensing factors
c. competence factors
d. initiating factors
e.enlisting factors

b. licensing factors

At what stage of the cell cycle do the key protein kinases, like cyclin-dependent kinase become activated? a. right after mitosis
b. right before mitosis
c. just before S phase
d. in the middle of the G2 phase
e. in the G0 phase

c. just before S phase

Cyclin-dependent kinase activity stays high through mitosis after rising prior to DNA synthesis. Which of the following results from its elevated activity?
a. Chromosomes decondense.
b. It suppresses the formation of new prereplication complexes.
c. It en

b. it surprises the formation of new pre replication complexes

Why does it appear that each origin can only be activated once per cell cycle?
a. Mcm proteins are displaced from the DNA after replication and cannot reassociate with a replication origin that has already fired.
b. The ORC is denatured after replication

a. Mcm proteins are displaced from the DNA after replication and cannot reassociate with a replication origin that has already fired

The structure and compilation of proteins in eukaryotes that forms the replicative complex are collectively known as the __________.
a. replicand
b. replicon
c. replisome
d. replimere
e. polymerizer

c. replisome

Which eukaryotic DNA polymerase replicates mitochondrial DNA and does not appear to be involved in nuclear DNA replication?
a. polymerase ?
b. polymerase ?
c. polymerase ?
d. polymerase ?
e. polymerase ?

a. polymerase gamma

Which eukaryotic DNA polymerase functions in DNA repair but does not appear to be involved in nuclear DNA replication?
a. polymerase ?
b. polymerase ?
c. polymerase ?
d. polymerase ?
e. polymerase ?

d. polymerase beta

Which eukaryotic DNA polymerase is both a DNA polymerase and an RNA primase, with the two catalytic activities present on different subunits. Its RNA primase and DNA polymerase activities are responsible for initiating the synthesis of each Okazaki fragme

a. polymerase gamma

Which eukaryotic DNA polymerase assembles the leading strand and most of the lagging strand fragments and is thought to be the primary replicative enzyme?
a. polymerase ?
b. polymerase ?
c. polymerase ?
d. polymerase ?
e. polymerase ?

b. polymerase delta

Which prokaryotic DNA polymerase resembles the eukaryotic DNA polymerase ? and which structural feature do the two polymerases have in common?
a. DNA polymerase I, sliding clamp
b. DNA polymerase II, sliding clamp
c. DNA polymerase III, sliding clamp
d. D

c. DNA polymerase III, sliding clamp

The PCNA sliding clamp used in eukaryotic replication was first discovered as an antigen that reacted with the autoantibodies of patients suffering from what disease? a. lupus erythematosus
b. diabetes
c. rheumatoid arthritis
d. myasthenia gravis
e. multi

a. lupus erythematosus

The clamp loader that loads PCNA onto DNA is called _______ and is analogous to the E. coli DNA polymerase III clamp loader complex.
a. RFC
b. KFC
c. NBC
d. TLC
e. SEC

a. RFC

What is responsible for removing the RNA primer and short DNA segment added by eukaryotic DNA polymerase ??
a. FEN-1
b. DNA polymerase ?
c. DNase H
d. a and c

a. FEN-1

What is responsible for filling the gap left by the nucleases that digest the primer and the short DNA segment added to it by polymerase ??
a. DNA polymerase ?
b. DNA polymerase ?
c. DNA polymerase ?
e. RNase H1

b. DNA polymerase delta

What is responsible for joining eukaryotic Okazaki fragments together? 747
a. DNA ligase
b. DNA polymerase ?
c. DNA polymerase ?
d. DNA polymerase ?
e. RNase H1

a. DNA ligase

Which eukaryotic DNA polymerase appears to play a role in nuclear DNA replication since replication cannot be completed in cells lacking this polymerase, even though its exact role has not yet been determined?
a. polymerase ?
b. polymerase ?
c. polymerase

c. polymerase e

If cells are given a very short exposure to radioactive DNA nucleotide precursors, where is most of the radiolabel located?
a. in the cytoplasm
b. associated with the nuclear matrix
c. in the mitochondria
d. in the DNA loops surrounding the nuclear matrix

b. associated with the nuclear matrix

If cells are given a very short exposure to radioactive DNA nucleotide precursors followed by unlabeled precursor for an hour or so before fixation, where is most of the radiolabel located?
a. in the cytoplasm
b. associated with the nuclear matrix
c. in t

d. in the DNA loops surrounding the nuclear matrix

What evidence suggests that the assembly of DNA into nucleosomes is a very rapid event?
a. Radiolabel is incorporated in a very short time.
b. Nucleosomes have a very unusual shape.
c. Electron micrographs of replicating DNA show nucleosomes forming on bo

c. Electron micrographs of replicating DNA show nucleosomes forming on both daughter duplexes very near the replication fork

What is the most common mechanism for repairing damage to DNA?
a. direct repair of the damage
b. selective excision of the damaged section and use of the complementary strand to replace excised portion c.simple removal of damaged portion without replaceme

b. selective excision of the damaged section and use of the complementary strand to replace excised portion

Which type of DNA repair removes the part of the strand having certain types of bulky lesions, like pyrimidine dimers and nucleotides to which various chemical groups have been attached?
a. nucleotide excision repair
b. base excision repair
c. mismatch re

a. nucleotide excision repair

In transcription-coupled repair, how is the presence of a lesion thought to be detected?
a. There are special enzymes that scan the DNA for such lesions.
b. The lesion is signaled by a stalled RNA polymerase.
c. The lesion is signaled by a stalled DNA pol

b. The lesion is signaled by a stalled RNA polymerase

What is the advantage of transcription-coupled repair? a. It allows the cell to do two things at once.
b. It ensures that the genes of least importance to the cell receive the highest priority on the repair list.
c. It ensures that the genes of greatest i

c. it ensures that the genes of greatest importance to the cell receive the highest priority on the repair list

Which method of repair can be slower, less efficient and responsible for correcting DNA strands in the parts of the genome that are not being currently transcribed?
a. transcription-coupled pathway of NER
b. global genomic pathway of NER
c. base excision

b. global genomic pathway of NER

What is the proper order of the steps involved in nucleotide excision repair?
1 - Release of the damaged DNA segment between the incisions
2 - Sealing of strand by DNA ligase
3 - Lesion recognition
4 - Separation of the duplex's two strands in the region

D.

After cuts are made on the two sides of the lesion in nucleotide excision repair, what holds the damaged part of the strand in position for a while before its final removal?
a. ionic bonds
b. van der Waals forces
c. H bonds
d. 3'-5' phosphodiester linkage

c. H bonds

What established a previously unsuspected link between DNA repair and transcription?
a. RNA synthesis was found to be instrumental in DNA repair.
b. A small subset of RNAs was found to be required for DNA repair.
c. Two subunits of a transcription factor

c. Two subunits of a transcription factor were found to be helicases that were responsible for unwinding DNA during DNA repair

Which DNA repair mechanism removes nucleotides altered by reactive chemicals present in the diet or produced by metabolism? Such alterations distort the helix less than other alterations.
a. nucleotide excision repair
b. base excision repair
c. mismatch r

b. base excision repair

Place the steps in base excision repair in the correct order.
1 - Damaged base is removed by cleavage of glycosidic linkage attaching it to deoxyribose of backbone.
2 - Baseless deoxyribose phosphate in site is excised by a specialized endonuclease and a

e.

What enzyme cleaves the DNA backbone to remove the beheaded deoxyribose phosphate during base excision repair?
a. an AP endonuclease
b. phosphodiesterase activity of polymerase ?
c. 5'�>3' exonuclease
d. 3'�>5' exonuclease
e. DNA glycosylase

a. an AP endonuclease

What enzyme is responsible for recognizing a chemical alteration in the DNA and removing the base by cleavage of the bond holding the base to the deoxyribose sugar moiety?
a. an AP endonuclease
b. phosphodiesterase activity of polymerase ?
c. 5'�>3' exonu

e. DNA glycosylase

Why did natural selection favor the use of thymine as a base in DNA instead of uracil even though uracil was presumably present in RNA, when it served as the genetic material during the early evolution of life?
a. Thymine was more stable.
b. Thymine paire

c. Retention of uracil as a DNA base would make it hard to tell whether a uracil was supposed to be at a particular site or whether it resulted from damage to cytosine

Which DNA repair mechanism recognizes a distortion in double helix geometry caused by DNA polymerase's insertion of an incorrect nucleotide during replication, one that escaped the enzyme's proofreading exonuclease?
a. nucleotide excision repair
b. base e

c. mismatch repair

What must the mismatch repair system be able to distinguish in order to tell which nucleotide of a mismatched pair to replace?
a. It must be able to distinguish the newly-made strand from the parental strand.
b. It must be able to distinguish which chain

a. it but be able to distinguish the newly-made strand from the parental strand

In mammalian cells, a complex of proteins binds to the broken ends of the DNA duplex and catalyzes a series of reactions that rejoin the broken strands. This is an example of what kind of repair?
a. nucleotide excision repair
b. base excision repair
c. mi

e. non homologous end joining

A double-stranded breakage repair pathway that requires the presence of a second chromosome carrying the same sequence of genes as the damaged chromosome is called _________.
a. nonhomologous end joining repair
b. homologous recombination
c. NHEJ
d. DNA m

b. homologous recombination

Patients with the classical form of xeroderma pigmentosum have a defect in one of the genes involved in ______________.
a. nuclear excitation repair
b. replication
c. base excision repair
d. transcription
e. translation

a. nuclear excitation repair

What happens once damage caused by lesions in the genome, like a thymidine dimer, is bypassed during replication and replication must continue?
a. The bypass DNA polymerase ? continues replication.
b. The replicative DNA polymerase ? continues replication

d. the replicative DNA polymerase delta e continues replication

The DNA polymerases in the relatively large family of polymerases that are specialized for incorporating nucleotides opposite various types of DNA lesions in the template strand engage in a type of DNA synthesis called __________. They have an uncanny abi

b. translesion synthesis, incorporate the nucleotide that would have paired with the undamaged version of the template base

What causes xeroderma pigmentosum (XP)?
a. XP patients possess a deficient translation system.
b. XP patients possess an overly efficient DNA repair system.
c. XP patients possess a deficient DNA repair system.
d. XP patients possess a deficient transcrip

c. XP patients possess a deficient DNA repair system

An inherited disorder characterized by acute sensitivity to light, neurological dysfunction due to neuron demyelination and dwarfism without an evident rise in skin cancer frequency is called ________.
a. xeroderma pigmentosum
b. Cockayne syndrome
c. Cock

b. Cockayne syndrome

Which DNA repair mechanism is deficient in cells from a Cockayne syndrome patient?
a. base excision repair
b. transcription-coupled pathway of nucleotide excision repair
c. global pathway of nucleotide excision repair
d. mismatch repair
e. double strand

b. transcription-coupled pathway of nucleotide excision repair

Cockayne syndrome patients have normal skin cancer rates. This suggests that which DNA repair mechanism is operating normally?
a. base excision repair
b. transcription-coupled pathway of nucleotide excision repair
c. global pathway of nucleotide excision

c. global pathway of nucleotide excision repair

Some XP patients in rare cases also have Cockayne syndrome symptoms. This happens in people who have specific mutations in a particular gene. What gene is affected when this happens?
a. XPA gene
b. XPB gene
c. XPD gene
d. XPX gene
e. CSA gene

c. XPD gene

Which disease is characterized by both DNA repair and transcription deficiencies, including sensitivity to the sun without elevated risks of cancer and a number of additional symptoms like brittle hair and scaly skin?
a. xeroderma pigmentosum
b. Cockayne

d. trichothiodystrophy

The two most common forms of skin cancer are ____________.
a. basal cell carcinoma and squamous cell carcinoma
b. malignant melanoma and squamous cell carcinoma c. basal cell carcinoma and malignant melanoma
d. basal cell carcinoma and keratoma
e. keratom

a. basal cell carcinoma and squamous cell carcinoma

From what kinds of cells does malignant melanoma arise?
a. connective tissue cells
b. epithelial cells
c. glial cells
d. skin pigment cells
e. concentric cells

d. skin pigment cells

What is one of the greatest risk factors for developing malignant melanoma as an adult?
a. saturated fats in the diet
b. unsaturated fats in the diet
c. a severe, blistering sunburn as a child or adolescent
d. application of too much hand cream
e. excessi

c. a severe, blistering sunburn as a child or adolescent

What is estimated to be responsible for up to 15% of colon cancers?
a. mutations in genes that encode the proteins required for a normal cytoskeleton
b. mutations in genes that encode the proteins required for mismatch repair
c. mutations in genes that en

b. mutations in genes that encode the proteins required for mismatch repair

Why do mutations that cripple the mismatch repair system inevitably lead to a higher mutation rate in other genes?
a. Mutations that cripple mismatch repair accelerate production of new mutants in other genes.
b. Mutations that cripple mismatch repair pre

d. Mutations that cripple mismatch repair prevent mistakes made during replication in other genes from being corrected

The ________ frequency of replication errors occurs when DNA polymerases copy short, repeated sequences called __________.
a. lowest, microsatellites
b. lowest, minisatellites
c. highest, minisatellites
d. highest, maxillariosatellites
e. highest, microsa

e. highest, micro satellites

Why does a high frequency of replication errors occur when DNA polymerases copy microsatellite regions of the genome?
a. DNA polymerases tend to stall in these regions.
b. DNA polymerases tend to slip as it moves along the template in these regions.
c. DN

b. DNA polymerases tend to slip as it moves along the template in these regions

Radon (222Rn) forms during the radioactive disintegration of what material?
a. water
b. uranium
c. radium
d. plutonium
e. lead

b. uranium

Exposure to radon causes cancer in what way?
a. When ingested, it causes double strand DNA breaks raising the risk of colon cancer.
b. When breathed into the lungs, it can lead to double strand DNA breaks that raise the lung cancer risks.
c. When touching

b. When breathed into the lungs, it can lead to double strand DNA breaks that raise the lung cancer risks

What is the deficit that seems to explain the fact that some individuals can suffer from the combined symptoms of xeroderma pigmentosum (XP) and Cockayne syndrome (CS)?

Individuals who suffer from symptoms of XP and CS have mutations in the XPB or XPD genes. These genes encode subunits of the transcription factor TFIIH, which plays a role in both transcription and DNA repair. The TFIIH of such an individual has defects t

What is the cause of CS and the widespread abnormalities associated with it in most CS sufferers?

Most cases of CS can be traced to a mutation in either the CSA or CSB genes, which are thought to be involved in the coupling of transcription to DNA repair. Such genes may also affect the transcription of certain genes, which may explain the more widespr

Why does a mutation in one of the genes that codes for a protein needed for mismatch repair lead to elevated mutation rates in other genes?

Such a mutation leads to mutations in other genes, since the repair system is disabled. It will fail to detect all of the mutations induced during the normal course of cell activities before the next cell division and they will thus be passed on to the ne

How could two different diseases be caused by a deficiency in the same protein?

The mutation in each case could be localized to different domains of the protein in question. These different domains are responsible for different activities. A deficiency in one activity may lead to one set of symptoms; a deficiency in the other activit

How does faulty mismatch repair lead to an elevated chance of developing colon cancer?

The highest frequency of replication errors occurs in regions of the genome where DNA polymerases must copy short, repeated sequences like those in micro satellites. At such sites, the enzyme tends to slip as it moves along the template. The gene that cod

What is the most serious environmental hazard that can cause double-stranded breaks in DNA that may go unrepaired or be repaired incorrectly thus leading to cancer?

Radon (222R) is a radioactive isotope formed during the disintegration of uranium. Some areas of the planet contain relatively high levels of uranium in the soil; houses built in these regions can contain dangerous levels of radon gas. About 1% of house i

Cultured mammalian cells are placed in culture in the presence of BrdU. At the end of one generation time (the first replication), what do the chromosomes look like?

Each chromosome will consist of two chromatids. One strand of each chromatid will contain thymidine along with the other nucleotides. The other strand will contain adenosine, cytosine, and guanosine, but the thymidine will be replaced by BrdU.

You are studying replication in a particular bacterial strain. At 37�C, the bacteria appear perfectly normal. If the temperature is raised to 43�C, however, they stop growing and are unable to replicate their DNA. If some of them are placed back at 37�C,

The bacteria probably carry a temperature-sensitive mutant of one of the genes whose product is essential for replication.

If a DNA polymerase were discovered that was able to synthesize DNA without the requirement of a free 3'hydroxyl group, which feature of DNA replication would be least likely to be needed?

There would be no need to make RNA primers with RNA primase

What kind of enzyme would be needed to eliminate the necessity for bidirectional replication at the replication fork?

The DNA polymerase would have to be able to synthesize DNA in both 5' ---->3' and 3' ---->5' directions

What is the major reason for the multiple initiation sites for eukaryotic replication?

There are two major reasons for the multiple initiation sites. First, eukaryotic genomes are bigger than prokaryotic genomes and tend to be linear instead of circular as prokaryotic genomes often are. Second, eukaryotic DNA polymerases are slower than tho

The DNA sequences flanking the ORC-binding site exhibit lowered duplex stability. What can you guess about the nucleotide sequence in this area?

The sequence of this region of the ARS is A-T rich. Since A-T base pairs bond with only two H bonds, sections of DNA containing these base pairs are held together less tightly than areas of DNA which have predominantly G-C base pairs (which contain 3 H bo

After exonucleases have excised the damaged portion of DNA, how can DNA polymerase fill in the gap? Is there a primer?

The free 3'-hydroxyl group at one end of the gap serves as the primer, allowing DNA polymerase to fill it in using the opposing strand as a complementary template

Do cells from XP patients exhibit any deficits in excision repair?

XP cells exhibited little or no ability to excise pyrimidine dimer. In fact, this ability was 10 times lower than in normal cells.

_____________ bonds are responsible for the polymer backbone of DNA, while _________ bonds primarily account for complementary base pairing in DNA.

1. covalent
2. hydrogen

The percentage of GC in a DNA sequence affects the � of the sequence because
a. the higher the amount of GC, the lower the Tm
b. the higher the amount of GC, the higher the Tm
c. GC rich sequences will have a higher Tm because they have less hydrogen bond

e. b and c

Which one of the following proteins and enzymes do not function at the origin of replication in E. coli?
a. DNA ligase
b. SSBs
c. Helicase
D. DnaA, dnaB, and dnaC proteins

a. DNA ligase

Which enzyme in E. coli is responsible for relieving the tension ahead of the fork that results when the DNA is unwound to form the replication bubble?
a. Replicase
b. Helicase
c. DNase
d. Gyrase

d. Gyrase

Which RNA polymerase transcribes protein-coding genes into mRNA in eukaryotes?
a. RNA polymerase IV
b. RNA polymerase III
c. RNA polymerase I
d. RNA polymerase II

d. RNA polymerase II

T/F: DNA polymerases always synthesize new DNA by adding nucleotides on to the 5' phosphate.

False

Which subunit of RNA polymerase establishes template binding to a promoter in prokaryotes?
a. Beta prime
b. Alpha
c. Sigma
d. Beta

b. alpha

If two DNA strands of identical length were analyzed, which of the following statements would be true of the melting temperature?
a. The DNA with the greater number of repetitive sequences will melt more slowly (lower T)
b. DNA with high GC content must h

d. DNA with a low AT content would melt more slowly

Which DNA polymerase is mainly responsible for genome replication in E. coli?
a. DNA polymerase III
b. DNA polymerase (alpha)
c. DNA polymerase I
d. DNA polymerase II

a. DNA polymerase III

Introns are known to contain termination codons (UAA, UGA, or UAG) yet these codons do not interrupt the coding of a particular protein. Why?
a. UAA, UGA, and UAG are initiator codons, not termination codons
b. Exons are spliced out of mRNA before transla

e. Introns are removed from mRNA before translation

An intron is a section of
a. protein that is clipped out posttranslationally
b. RNA that is removed during RNA processing
c. DNA that is removed during DNA processing
d. Transfer RNA that binds to the anticodon
e. Carbohydrate that serves as a signal for

b. RNA that is removed during RNA processing

What are the two main types if post-transcriptional modifications that take place in the mRNA of eukaryotes?
a. the addition of a polyA sequin at the 5' end of the gene and the addition of a polyU tail at the 3' end
b. the addition of a 7-mG cap at the 5'

b. the addition of a 7-mG cap at the 5' end of the transcript and the addition of a polyA sequence at the 3' end of the message

Which enzyme makes DNA from an RNA template?
a. RNA polymerase
b. Replicase
c. DNA polymerase
d. Reverse transcriptase

d. reverse transcriptase

Meselson and Stahl allowed baclene raise in 13N medium to replicate in 14N medium. At the end of two rounds of DNA replication, they observed ______ band(s) in their centrifugation tubes which was/were composed of _______.
a. 1; single strands of 15N DNA

d. 2; double strands of 14N DNA at the top and strands of 15N DNA base-paired to strands of 14N DNA in the middle

If 15% of the nitrogenous bases in a sample of DNA from a particular organism is thymine, what percentage should be cytosine?
a. 14%
b. 30%
c. 70%
d. 35%
e. 40%

d. 35%

Which of the following clusters of terms accurately describes DNA as it is generally viewed to exist in prokaryotes and eukaryotes?
a. double-stranded, parallel, (A+T)/(C+G) = variable, (A+G)/(C+T)= 1.0
b. double-stranded, antiparallel, (A+T)/(C+G)= varia

b. double-stranded, antiparallel, (A+T)/(C+G)= variable, (A+G)/(C+T)= 1.0

In addition to highly repetitive and unique DNA sequences, a third category of DNA sequences exists. What is it called and what types of elements are involved?
a. composite DNA, lelomeres and heterochromatin
b. dominant DNA, euchromatin and heterochromati

d. moderately repetitive DNA, SINEs, LINEs, and VNTRs

Why is an RNA primer considered essential for DNA synthesis by DNA polymerase III?
a. there is no particular reason; that is simply what has been observed
b. the enzyme requires a free 3'-OH group
c. the enzyme requires a free 3'-PO4 group
d. the enzyme r

b. the enzyme requires a free 3'-OH group

Which of the following options has the events of prokaryotic transcription in order?
a. elongation, termination, promoter binding, rho binding, transcription bubble
b. promoter binding, elongation, termination, rho binding, transcription bubble
c. rho bin

d. promoter binding, transcription bubble, elongation, rho binding, termination

Which of the following statements best describes Okazaki fragments?
a. they are formed in the leading strand
b. they add nucleotides to the elongating DNA
c. they are formed in the lagging strand
d. they are synthesized by primes

c. they are formed in the lagging strand

Which of the following statements is not true for DNA polymerases?
a. they can synthesize any sequence specified by template strand
b. they require a primer to initiate synthesis
c. they use dNTPs to synthesize new DNA
d. they produce newly synthesized st

e. they possess 5'----->3' exonuclease activity

Which of the following statements best describes the structure of a DNA molecule?
a. DNA is composed of an oxynucleoside in phosphate with a base attached to it
b. DNA is composed of a sugar-phosphate backbone with bases projecting towards the inside of t

b. DNA is composed of a sugar-phosphate backbone with bases projecting towards the inside of the backbone

Which of the following is not necessary for RNA polymerase to recognize the promoter of a bacterial genome?
a. sigma factor
b. origin of replication
c. -10 consensus sequence
d. -35 consensus sequence

b. origin of replication

If Avery, MacLeod, and McCarty had determined that the transforming molecule was a protein, what experimental results would not have been observed?
a. heat-killed cultures treated with RNase would transform the R cells
b. heat-killed cultures treated with

b. heat-killed cultures treated with protease would transform the R cells

Which of the following can account for multiple proteins from a primary transcript?
a. replication
b. alternative splicing
c. alternative editing
d. 5' methylation

b. alternative splicing

The binding of TBP to a polymerase II promoter:
a. causes a dramatic distortion in the conformation of DNA
b. results in the insertion into the minor groove of the double helix
c. results in the insertion into the major groove of the double helix
d. cause

e. a,b, and d

Transcribed regions present in the mature mRNA would arise from a ________ while transcribed regions NOT present in the mature mRNA would arise from a _______.
a. stop codon; initiation codon
b. anticodon; codon
c. intron; exon
d. exon; intron
e. initiati

d. exon; intron

Bacteria grown in a medium containing 15N H4CL for a number of generations so that all of the DNA is made up of fully "heavy" DNA. The bacteria are moved to a new medium and grown in 14N H4CL so that all new DNA will be "light". If replication were conser

e. half of the DNA is made up of 2 "light" strands and half of the DNA is made up of 2 "heavy" strands

What would the result be if a specific sigma subunit were mutated?
a. nothing would result, sigma is not essential
b. RNA polymerase would still bind at specific sites, but elongation would fail
c. RNA polymerase would fail to initiate transcription at th

c. RNA polymerase would fail to initiate transcription at the promoter specific to the sigma subunit

The end replication problem involves?
a. telomerase
b. an RNA template to synthesize new DNAs
c. an Okazaki fragment
d. a and c
e. a and b

e. a and b

T/F: Telomerase is an enzyme involved in the replication of the ends of eukaryotic chromosomes.

True

The RNA polymerase enzyme is said to be _______ because it stays attached to DNA over long stretches of template to make long mRNAs while it remains loose enough to move freely along the template.
a. recessive
b. processive
c. predominant
d. predominal
e.

b. processive

A new antibiotic is able to bind the rho (p) factor associated with some transcription processes, as a result this antibiotic would affect?
a. initiation of transcription
b. elongation of transcription
c. termination of all transcription
d. termination of

d. termination of some transcription

Attachment of the sigma factor:
a. increases the core enzyme's affinity for DNA promoter sites
b. decreases the core enzyme's affinity for DNA promoter sites
c. decreases the core enzyme's affinity for DNA promoter general
d. a and c

d. a and c

Strand initiation in DNA replication is accomplished when an enzyme lays down a primer. Of what molecule is that primer composed?
a. DNA
b. protein
c. carbohydrate
d. RNA
e. lipid

d. RNA

Those portions of DNA preceding the initiation site toward the 3' end of the template strand are said to be ______ that site.
a. upstream
b. downstream
c. to the right
d. to the left

a. upstream

Why has the one gene-one polypeptide hypothesis had to be modified?
a. it was totally wrong
b. enzymes sometimes consist of more than one polypeptide, each of which is coded for by its own genome
c. genes can be spliced differently to generate a variety o

c. genes can be spliced differently to generate a variety of related polypeptides

Both plants and animals produce hundreds of tiny RNAs that are relatively small in size (roughly 20-25 nucleotides in length). First discovered in nematodes, they are synthesized only at certain times during development or in certain tissues of a plant or

d. b and c

What is the only general transcription factor known to have enzymatic activity?
a. TFIID
b. TFIIH
c. TFIIIH
d. TFIIF
e. translational factor

b. TFIIH

It is important that the two strands of DNA near the front end of a gene are able to separate easily so that the gene can be expressed at the appropriate time. What should base composition in this part of the gene therefore be and why?
a. it should be AT-

b. it should be AT-rich since the smaller number of H bonds in that region of the gene will allow the strands to separate more easily

What interactions are responsible for holding the nitrogenous bases together stacked one on top of another in the center of a RNA molecule and contribute to the stability of the whole DNA molecule?
a. hydrophobic interactions
b. hydrophilic interactions
c

e. a and c

What type of DNA sequences range from about 10 to 100 base pairs and are found in clusters containing as many as 3000 repeats? These sequences tend to be unstable with the number of copies of a particular sequence often increasing or decreasing from one g

b. Minisatellite DNA

DNA replicating enzymes are known to have trouble copying genome regions that contain which class of DNA sequences? These stretches of DNA change in length through the generations and due to their variable lengths within the population, they have been use

c. Microsatellite DNA

Which of the following events directly triggers the initiation of replication at an ARS?
a. the departure of the ARS
b. the binding of other proteins to the ORC-origin complex
c. the departure of the ORC from the ARS
d. the binding of the ORC
e. the chang

b. the binding of other proteins to the ORC-origin complex

Which of the following is not a constituent of deoxyribonucleotides?
a. phosphate moieties
b. deoxyribose
c. ribose
d. organic bases

c. ribose

Which base pair(s) typically occur(s) in double-stranded DNA?
a. G�C
b. G�T
c. G�A
d. G�G

a. G-C

Which of the following terms is not used to describe a parameter of DNA topology?
a. wobble
b. writhe
c. twist
d. linking number

a. wobble

The ability of DNA to denature is important for which process?
a. DNA synthesis
b. nucleic acid hybridization experiments
c. RNA synthesis
d. all of the above

d. all of the above

Which of the following are removed from mRNAs during processing?
a. exons
b. noncoding sequences
c. RNA cap structure
d. poly(A) tail

b. noncoding sequences

The base in the wobble position of a codon
a. is the 5� (first) base.
b. is the 3� (third) base.
c. is the second base.
d. often contains adenine.

b. is the 3' (third) base

Approximately what percent of all human genes are expressed as alternatively spliced mRNAs?
a. 2
b. 25
c. 50
d. 90

d. 90

In eukaryotic cells, protein synthesis in the cytoplasm utilizes three types of RNA molecules. Which of the following
contains a three nucleotide sequence called the anticodon?
a. mRNA
b. tRNA
c. rRNA
d. all of the above

b. tRNA

Which of the following is not a recognized stage of protein synthesis in both prokaryotes and eukaryotes?
a. elongation
b. initiation
c. translation
d. termination

c. translation

Which of the following factors recognizes the UAG, UAA, and UGA codons?
a. RNA polymerase
b. DNA polymerase
c. termination factors
d. elongation factors

c. termination factors

Which codon serves as the start codon in mRNA for translation?
a. AGU
b. AUG
c. UGA
d. UGG

b. AUG

Which of the following is a protein that is involved in translation?
a. topoisomerase
b. ribosomal RNA
c. RNA polymerase
d. aminoacyl-tRNA synthetase

d. aminoacyl-tRNA synthetase

Which of the following structures interacts with ribosomes?
a. tRNA
b. mRNA
c. rRNA
d. all of the above

d. all of the above

Cellular protein synthesis proceeds in which direction?
a. carboxyl to amino terminus
b. amino to carboxyl terminus
c. 3�' to 5�
d. 5� to 3�

b. amino to carboxyl terminus

In which of these polymers are the monomers added one at a time?
a. DNA
b. rRNA
c. protein
d. all of the above

d. all of the above

DNA replication begins at sequences called
a. promoters.
b. initiators.
c. origins.
d. Okazaki fragments

c. origins

Which of the following lead(s) to a point mutation?
a. deamination of a cytosine base into a uracil base
b. benzo(a)pyrene conversion of guanine to a thymine base
c. deamination of 5-methyl cytosine into thymine
d. all of the above

d. all of the above

A Holiday structure is a(n)
a. intermediate in genetic recombination.
b. double-stranded DNA break.
c. collapsed replication fork.
d. thymine-thymine dimmer

a. intermediate in genetic recombination

Which of the following are enzymes that play a key role in the base excision repair of nucleotide mismatches and
damaged bases?
a. glycosamines
b. glycosidases
c. glycosylases
d. none of the above

c. glycosylases

The two chains of the DNA double helix are held together by ___________.

H bonds

H bonds individually are very weak and yet the strands of a DNA double helix can generally be separated only by very high temperatures approaching 100 degrees celsius. How does the weakness of H bonds account for such a strong interaction?
a. H bond stren

c. H bond strength is additive and the many H bonds holding the strands together make it stable

DNA binding proteins often can read the sequence of nucleotides along the DNA without having to separate the chains. How do they do this?
a. The conformations of the phosphate groups reflect the DNA sequence
b. The conformations of the deoxyribose sugars

d. The DNA binding proteins often contain domains that fit into the DNA grooves

How many residues are there in one full turn of the double helix?

10

The information encoded in DNA resides in __________.

the DNA base sequence

According to Watson and Crick's proposal, each new DNA double helix ____________.

Contains one strand from the original DNA molecule and one newly synthesized strand

DNA that is relaxed _______

has 10 base pairs per turn of DNA

Circular DNA in nature is invariably _____________ __________.

negatively supercoiled

An enzyme that creates a transient break in one duplex strand and then allows the intact, complementary strand to undergo a controlled rotation, relaxing the supercoiled molecule is called a ___________.

topoisomerase I