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BIO 1510 > exam 4 questions > Flashcards

exam 4 questions Flashcards

1
Q

Binary fission in prokaryotes does not require the

A

assembly of the nuclear envelope

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2
Q

Chromatin is composed of

A

DNA and protein

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3
Q

What is a nucleosome?

A

a region of DNA wound around histone proteins

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4
Q

what is the role of cohesin proteins in cell division?

A

they hold the DNA of the sister chromatids together

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5
Q

the kinetochore is a structure that functions to

A

connect the centromere to microtubules

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6
Q

separation of the sister chromatids occurs during

A

anaphase

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7
Q

why is cytokinesis an important part of cell division?

A

it is responsible for the proper separation of the cytoplasmic contents

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8
Q

what steps in the cell cycle represent irreversible commitments?

A

both b and c

b. The G1/S checkpoint
c. Anaphase

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9
Q

Cyclin-dependent kinases(Cdks) are regulated by

A

the periodic destruction of cyclins

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10
Q

The bacterial SMC proteins, eukaryotic cohesin proteins, and condensin proteins share a similar structure. Functionally they all

A

interact with DNA to compact or hold strands together

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11
Q

Genetically, proto-oncogenes act in a dominant fashion. this is because

A

they act in a gain-of-function fashion to turn on the cell cycle

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12
Q

The metaphase to anaphase transition involves

A

loss of cohesion between sister chromatids

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13
Q

the main difference between bacterial cell division and eukaryotic cell division is that

A

none of the above is correct

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14
Q

in animal cells, cytokinesis is accomplished by a contractile ring containing actin. The related process in bacteria is

A

septation via a ring of FtsZ protein, which is a tubulin-like protein

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15
Q

in comparing somatic cells and gametes, somatic cells are

A

diploid with twice the number of chromosomes

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16
Q

what are homologous chromosomes?

A

two genetically similar chromosomes, one from each parent

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17
Q

chiasmata form

A

between homologous chromosomes

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18
Q

crossing over involves each of the following with the exception of

A

the transfer of DNA between two sister chromatids

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19
Q

during anaphase I

A

homologous chromosomes move to opposite poles

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20
Q

at metaphase I the kinetochores of sister chromatids are

A

attached to microtubules from the same pole

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21
Q

what occurs during anaphase of meiosis II?

A

sister chromatids are pulled to opposite poles

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22
Q

which of the following does NOT contribute to genetic diversity?

A

metaphase of meiosis II

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23
Q

how does DNA replication differ between mitosis and meiosis?

A

during meiosis, there is only one round of replication for two divisions

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24
Q

which of the following is NOT a distinct feature of meiosis?

A

attachment of sister kinetochores to spindle microtubules

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25
Q

which phase of meiosis I is most similar to the comparable phase in mitosis?

A

telophase I

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26
Q

structurally, meiotic cohesins have different components than mitotic cohesins. This leads to the following functional difference:

A

centromeres remain attached during anaphase I of meiosis

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27
Q

mutations that affect DNA repair often also affect the accuracy of meiosis. This is because

A

the proteins involved in the repair of double-stranded breaks are also involved in crossing over

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28
Q

what property distinguished Mendel’s investigation from previous studies?

A

Mendel quantified his results

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29
Q

the F1 generation of the monohybrid cross purple (PP) x white (pp) flower pea plants should

A

all have purple flowers

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30
Q

the F1 plants from the previous question are allowed to self-fertilize. The phenotypic ratio for the F2 should be

A

3 purple: 1 white

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31
Q

which of the following is NOT a part of Mendel’s five-element model?

A

if an allele is present it will be expressed

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32
Q

an organism’s __ is/are determined by its __

A

phenotype; genotype

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33
Q

phenotypes like height in humans, which show a continuous distribution, are usually the result of

A

the action of multiple genes on a single phenotype

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34
Q

Japanese four o’clocks that are red and tall are crossed to white short ones, producing an F1 that is pink and tall. If these genes assort independently, and the F1 is self-crossed, what would you predict for the ratio of F2 phenotypes?

A

3 red tall: 6 pink tall: 3 white tall: 1 red short: 2 pink short: 1 white short

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35
Q

If the two genes in the previous question showed complete linkage, what would you predict for an F2 phenotypic ratio?

A

1 red tall: 2 pink tall: 1 white short

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36
Q

what is the probability of obtaining an individual with the genotype bb from a cross between two individuals with the genotype Bb?

A

1/4

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37
Q

In a cross of AaBbcc x AaBbCc, what is the probability of obtaining an individual with the genotype AABbCc?

A

1/16

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38
Q

when you cross true-breeding tall and short tobacco plants you get an F1 that is intermediate in height. When this F1 is self-crossed, it yields an F2 with a continuous distribution of heights. What is the best explanation for these data?

A

Height is determined by the additive effects of many genes

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39
Q

Mendel’s model assumes that each trait is determined by a single factor with alternative forms. We now know that this is too simplistic and that

A

a single gene can affect more than one trait, and traits may be affected by more than one gene

40
Q

Why is the white-eye phenotype always observed in males carrying the white-eye allele?

A

Because the allele is located on the X chromosome and males only have one X

41
Q

In an organism’s genome, autosomes are

A

all of the chromosomes other than sex chromosomes.

42
Q

What cellular process is responsible for genetic recombination?

A

Crossing over between homologues

43
Q

The map distance between two genes is determined by the

A

recombination frequency.

44
Q

How many map units separate two alleles if the recombination frequency is 0.07?

A

7 cM

45
Q

How does maternal inheritance of mitochondrial genes differ from sex linkage?

A

Since mitochondria are inherited from the mother, females and males are equally affected.

46
Q

Which of the following genotypes due to nondisjunction of sex chromosomes is lethal?

A

OY

47
Q

A recessive sex-linked gene in humans leads to a loss of sweat glands. A woman heterozygous for this will

A

have patches of skin with and without sweat glands.

48
Q

As real genetic distance increases, the distance calculated by recombination frequency becomes an

A

underestimate due to multiple crossovers that cannot be scored.

49
Q

Down syndrome is the result of trisomy for chromosome 21. Why is this trisomy viable and trisomy for most other chromosomes is not?

A

Chromosome 21 is a small chromosome with few genes so this does less to disrupt the genome.

50
Q

Genes that are on the same chromosome can show independent assortment

A

when they are far enough apart that odd numbers of crossovers is about equal to even.

51
Q

The A and B genes are 10 cM apart on a chromosome. If an A B/a b heterozygote is testcrossed to a b/a b, how many of each progeny class would you expect out of 100 total progeny?

A

45AB, 45ab, 5Ab, 5aB

52
Q

During the process of spermatogenesis, a nondisjunction event that occurs during the second division would be

A

better than the first division because only two of the four meiotic products would be aneuploid.

53
Q

What was the key finding from Griffith’s experiments using live and heat-killed pathogenic bacteria?

A

Genetic material can be transferred from dead to live bacteria.

54
Q

Which of the following is NOT a component of DNA?

A

The pyrimidine uracil

55
Q

Chargaff studied the composition of DNA from different sources and found that

A

the proportions of A equal that of T and G equals C.

56
Q

The bonds that hold two complementary strands of DNA together are

A

hydrogen bonds.

57
Q

The basic mechanism of DNA replication is semiconservative with two new molecules,

A

each with one new and one old strand.

58
Q

One common feature of all DNA polymerases is that they

A

synthesize DNA in the 5′-to-3′ direction.

59
Q

Which of the following is NOT part of the Watson–Crick model of the structure of DNA?

A

The two DNA strands are oriented in parallel (5′-to-3′).

60
Q

If one strand of a DNA is 5′ATCGTTAAGCGAGTCA3′, then the complementary strand would be:

A

5′ TGACTCGCTTAACGAT 3′.

61
Q

Hershey and Chase used radioactive phosphorus and sulfur to

A

differentially label DNA and protein.

62
Q

The Meselson and Stahl experiment used a density label to be able to

A

distinguish between newly replicated and old strands.

63
Q

The difference in leading versus lagging strand synthesis is a consequence of

A

both the physical structure of DNA and the action of

polymerase enzyme.

64
Q

if the activity of DNA ligase was removed from replication, this would have a greater effect on

A

synthesis on the lagging strand versus the leading strand.

65
Q

Successful DNA synthesis requires all of the following except

A

endonuclease.

66
Q

the synthesis of telomeres

A

requires telomerase, which uses an internal RNA as a

template.

67
Q

When mutations that affected DNA replication were isolated, two kinds were found. In cultures that were not synchronized (that is, not all dividing at the same time), one class put an immediate halt to replication, whereas the other put a much slower stop to the process. The first class affects functions at the replication fork like polymerase and primase. The second class affects functions necessary for

A

initiation: cells complete replication but cannot start a new round.

68
Q

The experiments with nutritional mutants in Neurospora by Beadle and Tatum provided evidence that

A

genes specify enzymes.

69
Q

What is the central dogma of molecular biology?

A

information passes from DNA to RNA to protein

70
Q

In the genetic code, one codon

A

both a and b

a. consists of 3 bases
b. specifies a single amino acid

71
Q

Eukaryotic transcription differs from prokaryotic in that

A

eukaryotes have three RNA polymerases

72
Q

An anticodon would be found on which of the following types of RNA?

A

tRNA (transfer RNA)

73
Q

RNA polymerase binds to a__ to initiate ___ .

A

promoter; transcription

74
Q

During translation, the codon in mRNA is actually“read”by

A

the anticodon in a tRNA

75
Q

You have mutants that all affect the same biochemical pathway. If feeding an intermediate in the pathway supports growth, this tells you that the enzyme encoded by the affected gene

A

acts before the intermediate used

76
Q

the splicing process

A

can produce multiple mRNAs from the same transcript

77
Q

The enzyme that forms peptide bonds is called peptidyl transferase because it transfers

A

the growing peptide from a tRNA to the next amino acid

78
Q

In comparing gene expression in prokaryotes and eukaryotes

A

Both a and c are correct.

a. eukaryotic genes can produce more than one protein.
c. both produce mRNAs that are colinear with the protein.

79
Q

The codon CCA could be mutated to produce

A

a silent mutation

80
Q

An inversion will

A

only cause a mutant phenotype if the inversion breakpoints fall within a gene

81
Q

What is the relationship between mutations and evolution?

A

mutations can create new alleles

82
Q

In prokaryotes, control of gene expression usually occurs at the

A

initiation of transcription.

83
Q

Regulatory proteins interact with DNA by

A

binding to the major groove of the double helix and interacting with base-pairs.

84
Q

In E.coli, induction in the lac operon and repression in the trp operon are both examples of

A

negative control by a repressor.

85
Q

The lac operon is controlled by two main proteins. These proteins

A

act in the opposite fashion, one negative and one positive.

86
Q

In eukaryotes, binding of RNA polymerase to a promoter requires the action of

A

general transcription factors.

87
Q

In eukaryotes, the regulation of gene expression occurs

A

at the level of transcription initiation, or post-transcriptionally.

88
Q

In the trp operon, the repressor binds to DNA

A

in the presence of trp

89
Q

The lac repressor, the trp repressor and CAP are all

A

allosteric proteins that bind to DNA and an effector.

90
Q

Specific transcription factors in eukaryotes interact with enhancers, which may be a long distance from the promoter. These transcription factors then

A

can interact with the transcription apparatus via DNA looping.

91
Q

Repression in the trp operon and induction in the lac operon are both mechanisms that

A

allow the cell to control the level of enzymes to fit

environmental conditions.

92
Q

Regulation by small RNAs and alternative splicing are similar in that both

A

Both a and b are correct.

a. act after transcription.
b. act via RNA/protein complexes.

93
Q

Eukaryotic mRNAs differ from prokaryotic mRNAs in that they

A

are not colinear with the genes that encode them.

94
Q

In the cell cycle, cyclin proteins are produced in concert with the cycle. This likely involves

A

control of initiation of transcription of cyclin genes, and ubiquitination of cyclin proteins.

95
Q

A mechanism of control in E.coli not discussed in this chapter involves pausing of ribosomes allowing a transcription terminator to form in the mRNA. In eukaryotic fission yeast, this mechanism should

A

not occur as transcription occurs in the nucleus and translation in the cytoplasm.

BIO 1510 (10 decks)

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