Which of the following steps in protein synthesis require ATP hydrolysis?
a. joining two amino acids together on the ribosome
b. attaching an amino acid to a tRNA
c. binding of tRNA to the ribosome
d. binding of the ribosome to mRNA
e. base -pairing of co
b. attaching an amino acid to a tRNA
What is the primary limitation of the PCR technique?
a. the ability to isolate DNA of sufficient purity to get a clean sample
b. the difficulty of isolating DNA fragments of sufficient length to get useful copies
c. the need to know at least part of the D
c. the need to know at least part of the DNA sequence of the sample
A protein with leucine zipper motif is:
a. a DNA-binding protein
b. a chromatin protein
c. a component of the ribosome
d. a hormone.
e. none of the above
a. a DNA-binding protein
Initiation of transcription by RNA polymerase II in eucaryotes requires:
a. ligand binding to an inhibitory protein
b. several transcription factors, one of which phosphorylates RNA polymerase
c. the binding of an activator protein to the gene
d. the prod
b. several transcription factors, one of which phosphorylates RNA polymerase
When two lymphocytes are fused together, which of the following best describes the behavior of the proteins found in the plasma membranes of the two cells?
a. They are rapidly taken up by coated vesicles
b. The proteins from each cell remain associated wi
c. The proteins from each cell diffuse through the bilayer, intermix, and become uniformly distributed over the surface of the hybrid cell
What is responsible for proofreading the daughter strand and correcting mistakes during DNA replication?
a. DNA polymerase
b. small nuclear ribonucleoprotein particles
c. DNA primase
d. Okazaki factor
e. DNA ligase
a. DNA polymerase
During DNA replication, DNA is synthesized on the lagging strand as:
a. a continuous strand of DNA
b. a discontinuous strands of DNA
c. Okazaki fragments
d. a continuous strands of RNA
e. a discontinuous strands of RNA
c. Okazaki fragments
What seals the nicks in the sugar-phosphate backbone of the DNA that are produced during replication?
a. DNA polymerase
b. DNA primase
c. DNA ligase
d. DNA nickase
e. RNA polymerase
c. DNA ligase
A prominent nucleolus indicates that a cell is:
a. getting ready to divide
b. replicating its DNA
c. active in protein synthesis
d. inactive in protein synthesis
e. dying
c. active in protein synthesis
Gene regulatory proteins interact with DNA primarily:
a. by hydrogen bonding with the edges of the nucleotide bases exposed in the major and minor grooves
b. by hydrogen bonding with the sugar - phosphate backbone
c. by disrupting the hydrogen bonding bet
a. by hydrogen bonding with the edges of the nucleotide bases exposed in the major and minor grooves
Most transmembrane proteins traverse the lipid bilayer as
a. straight alpha helices, rich in hydrophobic amino acids
b. curved alpha helices
c. mixtures of alpha helices and beta sheets
d. coiled coils
e. globular proteins
a. straight alpha helices, rich in hydrophobic amino acids
Which of the following pairs of codons might you expect to be read by the same tRNA as a result of wobble?
a. CUU and UUU
b. GAU and CAU
c. CAC and CAU
d. AAU and AGU
e. CCA and GCU
c. CAC and CAU
Which method is used to separate DNA fragments in order to determine the base sequence?
a. ultracentrifugation
b. PAGE
c. agarose gel electrophoresis
d. in situ hybridyzation
e. Western blotting
b. PAGE
Gene duplication in eucaryotic cells is caused by
a. mutation
b. equal crossing over
c. unequal crossing over
d. viruses
e. DNA polymerase
c. unequal crossing over
Over time, families of proteins have evolved by the process of:
a. mutation
b. equal crossing over
c. alternative RNA splicing
d. exon shuffling
e. viral infection
d. exon shuffling
The DNA base sequence "TATA" is part of the consensus sequence for:
a. the termination sequence for RNA synthesis
b. the promoter sequence for RNA polymerase
c. the initiation site for DNA replication
d. the nucleolar organizer region
e. an enhancer seque
b. the promoter sequence for RNA polymerase
To which part of the ribosome does the mRNA bind?
a. the large subunit
b. the small subunit
c. the A-site
d. the P-site
e. the 50S subunit
b. the small subunit
Negative regulation of gene expression is characterized by:
a. ligand binding to the regulatory proteins.
b. the binding of a repressor protein to the gene
c. the binding of an activator protein to the gene
d. mRNA degradation
e. the binding of a represso
b. the binding of a repressor protein to the gene
In situ hybridization can be used to determine:
a. the sequence of the cloned gene
b. the distribution of proteins in tissues
c. the position of the cloned fragment of DNA on the plasmid
d. the size of a gene
e. the distribution of a given type of mRNA in
e. the distribution of a given type of mRNA in different tissues
The enzyme that synthesizes the mRNA is
a. RNA polymerase I
b. RNA polymerase II
c. RNA polymerase III
d. DNA polymerase a
e. DNA polymerase d
b. RNA polymerase II
Although DNA is chemically unstable, the mutation rate of DNA over evolutionary time is very slow. How is this paradox explained?
a. The DNA in germ cells is stabilized by proteins that protect it from damage
b. One base of a pair usually remains undamage
c. Cells have a DNA mismatch repair system that constantly detects and repairs damage to the DNA
The highly condensed, transcriptionally inactive form of chromatin in interphase cells is called:
a. inactive euchromatin
b. chromatid
c. euchromatin
d. heterochromatin
e. 30 nm fiber
d. heterochromatin
Which of the following best describes the mobility of membrane proteins?
a. They are immobile
b. They diffuse freely within the plane of the lipid bilayer
c. They diffuse freely within the plane of the lipid bilayer unless they are restricted from doing s
c. They diffuse freely within the plane of the lipid bilayer unless they are restricted from doing so
The translation of an mRNA molecule in a polyribosome:
a. produces a single protein molecule
b. occurs only in procaryotes
c. produces many copies of the same protein
d. occurs only in eucaryotes
e. produces many different proteins
c. produces many copies of the same protein
During translation, new amino acids are added to which end of the growing polypeptide chain?
a. the 3'-end
b. the 5'-end
c. the amino-terminus
d. the carboxyl-terminus
e. either end
d. the carboxyl-terminus
RNA can be used as a primer for DNA replication in cells because:
a. primase is not found at the replication fork
b. RNA does not base-pair to the DNA template
c. Primase synthesizes RNA in the 3'- to -5' direction
d. RNA spontaneously hudrolyzes after DN
e. Primase can join ribonucleotides together on a single-stranded DNA template without the need for its own primer
A proto-oncogene is:
a. viral gene that causes cells to become cancerous
b. the normal cellular version of a viral gene that causes cells to become cancerous
c. a gene found in protozoa that enables them to form tumorous growths in plants
d. a viral gene
b. the normal cellular version of a viral gene that causes cells to become cancerous
Chromosome crossing over normally occurs:
a. at any time during the cell cycle
b. during mitosis
c. during meiosis
d. during fertilization
e. when cells are exposed to ionizing radiation
c. during meiosis
Transposable elements that travel via an RNA intermediate are called:
a. retroviruses
b. VTNR sequences
c. retrotransposons
d. reverse transcriptase
e. RNA viruses
c. retrotransposons
Protein synthesis is terminated when:
a. the ribosome hits the loop caused by the termination signal
b. the ribosome reaches the poly-A tail of the mRNA
c. the stop-tRNA binds to the stop codon
d. a release factor binds to the stop codon in the A-site
e.
d. a release factor binds to the stop codon in the A-site
How are eucaryotic gene regulatory proteins able to affect transcription when their binding sites are far from the promoter?
a. by binding to their binding site and sliding to the site of RNA polymerase assembly
b. by looping out the intervening DNA betwe
b. by looping out the intervening DNA between their binding site and the promoter
Sexual reproduction:
a. introduces new genes into a population
b. enables a population to get rid of deleterious alleles because offspring that inherit them die
c. select for those genes that make individuals better adapted to the environment
d. produces
d. produces offspring that are different from either parent and from each other
How many replication origins are present in the eucaryotic genome?
a. one
b. one per homologous chromosome pair
c. one per chromosome
d. a large number per chromosome
e. none
d. a large number per chromosome
During transcription, new nucleotides are added to which end of the growing RNA chain?
a. the 2'-end
b. the 3'-end
c. the 5'-end
d. either end
e. none of the above
b. the 3'-end
What type of damage does ultraviolet radiation cause to DNA?
a. depurination
b. deamination
c. thymine dimerization
d. sugar-phosphate cleavage
e. dephosphorylation
c. thymine dimerization
Enzymes that cut DNA molecules at a specific nucleotide sequences are called:
a. restriction nucleases
b. exonucleases
c. glycosylases
d. DNA polymerase
e. DNA topoisomerase
a. restriction nucleases
Which of the following components of the plasma membrane decreases the permeability of the lipid bilayer?
a. cholesterol
b. unsaturated fatty acids
c. spectrin
d. saturated fatty acids
e. sphingomyelin
a. cholesterol
A cDNA library is derived from:
a. isolated single-stranded DNA
b. isolated double-stranded DNA
c. isolated mRNA
d. restriction fragments
e. cloning vectors
c. isolated mRNA
A visual display of the complete set of human metaphase chromosomes is called:
a. a genomic library
b. a cDNA library
c. in situ hybridization
d. a karyotype
e. a metaphase plate
d. a karyotype
A self-replicating agent derived from bacteria that is used in DNA cloning is:
a. a telomere
b. a plasmid
c. an oncogene
d. a kinetochore
e. a restriction enzyme
b. a plasmid
Given the sequence of the DNA strand below, write the sequence of the RNA that would be transcribed and show its polarity.
DNA sequence:
5' -T--G--C--A--T--A--C--T--T--A - 3'
3'-A--C--G--U--A--U--G--A--A--U -5'
transposable element
Segment of DNA that can move from one position in a genome to another
RNA splicing
Process by which the very long primary transcript is converted into the much shorter mRNA molecule
topoisomerase
Enzyme that reversibly cuts one of the DNA strands to form a swivel that eliminates the need to spin the entire double helix during DNA replication.
7-methyl guanosine
The molecule that caps mRNA in eucaryotes
telomere
Chromosome region (sequence) required for replication of the ends of eucaryotic chromosomes
reverse transcriptase
Enzyme in the AIDS virus that makes a double-stranded DNA copy from a single-stranded RNA template molecule.
mutation
Heritable alteration in the nucleotide sequence of a chromosome
introns
DNA sequences that are transcribed into RNA but subsequently spliced out in the formation of mRNA.
codon
Sequence of three nucleotides in a mRNA molecule that represents the instruction for incorporation of a specific amino acid into a polypeptide chain