In 1928, Frederick Griffith established that _______.
heat-killed bacteria harbor the constituent(s) necessary to convey genetic properties to living bacteria
To be certain that the extract prepared from virulent cells still contained the transforming principle that was present prior to lysis, Avery _______.
incubated nonvirulent cells with the complete extract
If Avery had observed transformation using only the extracts containing degraded DNA, degraded RNA, and degraded protein, but NOT the extract containing degraded polysaccharides, he would have concluded that ______
polysaccharides are the genetic material
The Hershey and Chase experiments involved the preparation of two different types of radioactively labeled phage. Which of the following best explains why two preparations were required?
It was necessary that each of the two phage components, DNA and protein, be identifiable upon recovery at the end of the experiment.
Which of the following statements best represents the central conclusion of the Hershey-Chase experiments?
DNA is the identity of the hereditary material in phage T2.
Which of the following outcomes would be most likely if the Hershey-Chase experiments were repeated without the step involving the blender?
Both preparations of infected bacteria would exhibit radioactivity
What observation did Griffith make in his experiments with Streptococcus pneumoniae?
The mouse did not survive when injected with a mixture of live, avirulent (smooth) Streptococcus pneumoniae and heat?killed, virulent Streptococcus pneumoniae
What results did Avery, McLeod, and McCarty obtain in their experiments with virulent bacteria?
DNase destroyed the transforming activity.
Identify three possible components of a DNA nucleotide
deoxyribose, phosphate group, thymine
True or False:
Guanine and adenine are purines found in DNA
true
Which of the following statements about DNA structure is true?
A
A. The nucleic acid strands in a DNA molecule are oriented antiparallel to each other, meaning they run in opposite directions.
B. Hydrogen bonds formed between the sugar?phosphate backbones of the two DNA chains help to stabilize DNA structure.
C. Nucl
What is the complementary DNA sequence to 5? ATGCTTGACTG 3??
5? CAGTCAAGCAT 3
true or false: In forming a nucleotide, phosphorus is most often attached to the nucleoside at the C?5? position of the sugar
true
Write the complementary sequence for the following DNA sequence, in order from 3' to 5':
5- CGATATTGAGCTAAGCTT -3
3- GCTATAACTCGATTCGAA -5
RNA differs from DNA in all of the following ways except by
The 5?-3? orientation of the polynucleotide strand
Of the following DNA strands in combination with their complementary strands (forming double helices), three undergo a hyperchromic shift with a T m of about 42�C. Which one has a T m of 52�C?
TCATGCGATC
What makes up the protein component of a nucleosome?
Two tetramers of histone proteins
What is the first order of chromatin packing?
Coiling around nucleosomes
true or false: The second order of chromatin packing occurs when nucleosomes coil together to form a fiber that is 300 nm in diameter.
False
That some organisms contain much larger amounts of DNA than are apparently "needed" and that some relatively closely related organisms may have vastly different amounts of DNA is more typical in ________.
eukaryotes than in prokaryote
Cytokinesis in animal cells is accomplished by constriction of the cell along the plane of cell division (formation of a cleavage furrow). In plant cells, which have cell walls, a completely different mechanism of cytokinesis has evolved.
A & C
A) Vesicles from the Golgi apparatus move along microtubules, coalesce at the plane of cell division, and form a cell plate.
B) The plasma membrane of the parent cell grows inward, eventually joining with the cell plate.
C) The cell plate consists o
When is DNA duplicated for cell division?
During the S period of interphase
true or false: The primary differences observed for plant cell mitosis relative to animal cell mitosis occur during telophase
true
Which list of steps in the eukaryotic cell cycle is given in the correct order? (step order listed left to right)
. . . G1 - S - G2 - M - G1 . . .
true or false: Haploid cells do not undergo mitosis.
False
Each of the following events occurs during mitosis except _______
A
A) polar microtubules contract, pulling attached chromosomes toward the poles
B) chromosomes condense
C) microtubules assemble between centrioles
D) nuclear membrane breaks down
true or false:
The cell cycle consists of a shorter phase called interphase and a longer phase called mitosis, during which cell division takes place.
false
Which structure is not found in all mitotic cells?
D
A) Sister chromatids
B) Kinetochore
C) Spindle fibers
D) Centriole
What is the arrangement of chromosomes during metaphase?
Sister chromatids are aligned along the equatorial plane of the cell
The parent cell that enters meiosis is diploid, whereas the four daughter cells that result are haploid.
Which statement correctly describes how cellular DNA content and ploidy levels change during meiosis I and meiosis II? (Note: Ignore any effects of cr
DNA content is halved in both meiosis I and meiosis II. Ploidy level changes from diploid to haploid in meiosis I, and remains haploid in meiosis II.
Separation of sister chromatids occurs _______
at anaphase in mitosis and anaphase II in meiosis
true or false: The end result of meiosis is four haploid daughter cells.
true
Novel combinations of genes can arise from _______
reciprocal exchange of DNA between homologs during prophase I
true or false: A dyad is composed of two homologous chromosomes joined at a common centromere
False
A cell has 16 chromosomes. How many chromosomes would its daughter cells have after meiosis?
8
Which of the following statements about meiosis is true?
A
A) The second meiotic division is similar to mitosis in that the sister chromatids separate.
B) During meiosis, homologous chromosomes behave autonomously of one another.
C) The products of meiosis contain a diploid complement of chromosomes.
D) A tetra
Crossing over refers to _________
Genetic exchange between nonsister chromatids during meiosis
In humans, what is a fundamental difference between the production of female gametes and male gametes?
The production of female gametes involves an unequal division of cytoplasm
Which of the following would be true of a plant heterozygous for a single gene controlling flower color? (Assume complete dominance)
A
A) If crossed with another heterozygous plant, the majority of progeny will have the dominant flower color.
B) About half of all its progeny will display the recessive flower color.
C) It displays the recessive flower color.
D) It will produce gametes w
true or false: The 3:1 phenotypic ratio observed among progeny of an F1 X F1 cross requires random union of gametes.
true
Of the methods listed below, which would be the best way to determine which of two alleles of a gene is dominant to the other?
D
A) Count the number of recessive individuals resulting from a cross between two recessive parents.
B) Perform crosses between series of randomly selected pairs to see which phenotype occurs more frequently.
C) Observe the relevant phenotype among the pr
How could the botanist best determine whether the genotype of the green-pod plant is homozygous or heterozygous?
cross the green pod plant with the yellow pod plant
Independent assortment explains _______
why a collection of meiotic products that includes gametes of genotype Ab will also include gametes of genotype AB in roughly the same proportion
true or false: Independent assortment occurs only in cells that are heterozygous for two genes (AaBb) and not in cells that are completely homozygous (AABB or aabb).
false
Which of the following genotypes represents a gamete produced by a failure to segregate during meiosis in a cell of genotype AaBbCC?
AaBC
Which of the following phenomena is a consequence of Independent Assortment?
B
A) Smooth seed trait is dominant to wrinkled seed trait in peas.
B) The phenotypic ratio among phenotypes produced from an F1 X F1 dihybrid cross is 9:3:3:1.
C) Pure breeding plants, when mated with each other, produce completely homozygous offspring.
D
true or false: The 9:3:3:1 ratio exhibited in the F2 generation of a dihybrid cross is a genotypic ratio.
false
A pea plant is heterozygous for two genes; one controlling height, one controlling color. The genotype is written PpTt. Based on the Law of Independent Assortment, approximately what proportion of the pollen produced by this plant should have the genotype
1/4
true or false: A couple has two boys and is expecting a third child. The probability that the third child will be a boy is �
true
What is the probability of a family with six children having three boys and three girls?
20/64
Part C
If three differently colored dice are rolled at the same time, what is the probability that a 6 will be the outcome on each one?
1/216
You would like to know whether the progeny of a pair of mated fruit flies are distributed among the resulting four phenotypic classes in a 1:1:1:1 ratio. You perform a chi-square test and obtain a p value of 0.04. Assuming you have done the test correctly
A
A) The differences between the observed and expected counts are too large to be attributed to chance.
B) Approximately 4% of the offspring lie outside the range of values expected for a 1:1:1:1 ratio.
C) The phenotypic ratio is actually 9:3:3:1
D) The t
true or false:
The larger the number of total individual counts in a chi-square test, the higher the degrees of freedom (df).
false
The expected ratio of phenotypes among the progeny of a test cross is 1:1:1:1. Out of 200 total resulting progeny, 48 occur in one of the four phenotypic classes. Given this information, which of the following must also be true?
C
A) The progeny of this cross do not conform to a 1:1:1:1ratio.
B) Since 48 is so close to the expected value, there is no need to calculate chi square before drawing a conclusion about the ratio.
C) The value of observed - expected for this cell = -2.
D
Assume that a black guinea pig crossed with an albino guinea pig produced 5 black offspring. When the albino was crossed with a second black one, 4 black and 3 albino offspring were produced. What genetic explanation would apply to these data?
Albino = recessive; black = dominant.
The fundamental Mendelian process that involves the separation of contrasting genetic elements at the same locus would be called
segregation.
true or false: Assuming complete dominance, a 3:1 phenotypic ratio is expected from a monohybrid sib or self-cross.
true
true or false: A 9:3:3:1 phenotypic ratio is expected from a dihybrid testcross
false
With incomplete dominance, a likely ratio resulting from a monohybrid cross would be ________
1:2:1
How many different phenotypes are possible in a one gene/three allele system that displays codominance
6
Which of the following is the most likely example of codominance?
B
A) A pure-breeding tall plant is crossed to a pure-breeding short plant. All their progeny are of medium height.
B) A pure-breeding plant with red flowers is crossed to a pure-breeding plant with white flowers. All their progeny have flowers with some r
true or false: The color dilution gene in horses is an example of incomplete dominance
true
In a mating between individuals with the genotypes IAi � ii, what percentage of the offspring would be expected to have the O blood type?
50%
In a mating between individuals with the genotypes IAIB � ii, what percentage of the offspring would be expected to have the O blood type?
0%
what contains all of the necessary information for virus protection?
isolated viral DNA is directly inserted into bacterial cells
found throughout the cell
protein
found only in the nucleus
DNA
DNA is composed of
nucleotides
nucleotides are composed of ? (3)
1. nitrogen containing base
2. pentose (5-carbon sugar)
3. phosphorous group
chemical that carries heredity?
DNA
pyrimidine ring is a single or double ring?
single
purine ring is a single or double ring?
double
difference between a nucleoside and a nucleotide
nucleoside: sugar base
nucleotide: sugar base + phosphate
Who concluded that there were 2 sugar phosphate backbones in a helix, with nitrogenous base pairs in the molecules interior?
Rosalind Franklin
Rosalind Franklin used what to study DNA?
x-ray crystallography
w many hydrogen bonds are there between Adenine and Thymine?
2
how many hydrogen bonds are there between Guanine and Cytosine?
3
density of DNA depends on?
relative G+C content (the higher the G+C , the denser)
True or false: there is a relationship between G+C content and buoyant density?
true
denatured
double stranded DNA becomes single stranded
The melting point of DNA is determined when?
half of the DNA in a sample becomes single-stranded
True or false: The more G+C in DNA the more hydrogen bonds
True
______ denatures?
heat
_________ renatures?
cooling
time in which half o the DNA is reannealed; indicates how complicated (the number of base pairs) a genome is
C t 1/2
DNA is forced to migrate through a semi-solid substance in the presence of an electric field
electrophoresis
Is DNA negatively or positively charged?
negatively
DNA migrates at a speed directly proportional to its
length
chromosomes
transmit/carry genes to new cells, either through mitosis or meiosis
chromosomes
provide a template for genetic information reading
chromosomes of a virus consist of
single stranded DNA
double stranded DNA
single stranded RNA
double stranded DNA
the single or double stranded nucleic acid of viruses can be ______ or ______?
circular or linear
bacterial chromosomes are?
double stranded DNA and circular
bacterial chromosomes are located in the ?
nucleoid
if a DNA molecule supercoils, the size...?
shrinks
what maintains supercoiling
topoisomerases
topoisomerases
cut one or both strands of DNA, twist the helix, and reconnect the ends
eukaryotic chromosomes are found in the
nucleus
when cells are not dividing, chromosomes are uncoiled to form
chromatin
how many chromosomes are in the human body
46
Names of Histones
H1, H2A, H2B, H3, H4
what plays an important role in producing repeating units along the chromatin axis necessary for proper chromatin structure
histones
chromatin is composed of linear rays of spherical particles/beads called
nucleosomes
regions of chromatin containing DNA and H2A, H2B, H3, and H4
nucleosomes
nucleosomes contain DNA wound around histone _____ assembled using two of each histone
octamers
the linker/spacer DNA is often bound by ?
histone H1
necleosomes coil into
solenoids
centromere
constricted region of a chromosome that functions to move the chromosome during mitosis or meiosis
telomere
the end of a chromosome that works to protect the end of the DNA molecule
metacentric
centromere is located in the middle
submetacentric
centromere is located between middle and end
acrocentric
centromere is located close to end
telocentric
centromere is located at the end
sedimentation equilibrium centrifugation reveals
satellite DNA
if chromosomes have the same banding patterns that means they have the same
genetic material
homologous chromosomes
each pair of matching chromosomes
homolog
each chromosome of a pair
diploid (2n)
cells contain homologous chromosomes
haploid (n)
cells contain only 1 homolog of each pair
what are the only haploid cells?
gammetes (sperm and egg)
strands of chromatin are uncoiled and dispersed in ______ cells?
non dividing
all chromosomes tightly coil and condense in ____ cells
dividing
In the cell cycle, before cell division, DNA is _____ each daughter cell receives an __________
replicated; exact copy of DNA
each duplicated chromosome has 2
sister chromatids
sister chromatids are attached via?
centromere
mitosis produces
genetically identical daughter cells
asexual reproduction mitosis or meiosis?
mitosis
gametes
haploid products of meiosis
meiosis ______ the chromosome number
reduces, diploid to haploid
meiosis reduces genetic material by
1/2
what preserves the number of chromosomes, producing genetically identical daughter cells
mitosis
what reducesthe number of chromosome sets from 2 to 1 producing 4 genetically distinct cells that differ
meiosis
what produces genetic variation
meiosis
biparental inheritance
diploids contains 2 copies of each gene- one copy from each parent
genetic recombination
crossing over between nonsister chromatids
independent assortment
the specific chromosome that you inherit from each pair of homologous chromosomes is random
specialized cells that set aside early during development for the production of gametes
germ cells
p generation
true breeding parents
F1 generation
hybrid offspring of the P generation
F2 generation
offspring of F1 generation
alleles
alternative versions of a gene
variation in the _____ of a gene ca lead to different versions of an allele
nucleotide sequence
dominant allele
determines the organisms appearance
law of segregation
the 2 alleles for a heritable character separate during gamete formation and end up in different gametes
genotype
genetic makeup of an individual
phenotype
physical expression of the genetic makeup
homozygous
when 2 alleles for a trait are the same
heterozygous
2 different alleles for a gene
true or false: all homozygotes are true breeding
true
monohybrid cross
cross between heterozygotes of a single character
chromosomal theory of inheritance
the separation of chromosomes during meiosis could be the basis for Mendel's principles of segregation and independent assortment
product rule
probability that 2 or more independent events will occur together is the product of their individual probabilities
sum rule
probability of obtaining any single outcome, where that outcome can be achieved in more than 1 way, is equal to the individual probabilities of all such events