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Genetics Final Exam > Past Exam 2017 > Flashcards

Past Exam 2017 Flashcards

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Biology 101 flashcards
1
Q

The 4 subunits that compose DNA are

A

Nucleotides

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2
Q

In the Hershey and Chase experiment designed to determine molecule of heredity, what was radiolabelled with 35S

A

Protein

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3
Q

X-ray data showed that the spacing between repeating units along the axis of the DNA helix is

A

3.4 angstroms

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4
Q

_______ bonds are responsible for the chemical affinity between A and T (or G and C)

A

Hydrogen

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5
Q

________-form DNA spirals to the right and is the major form of naturally occurring DNA molecules

A

B

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6
Q

DNA replication occurs through a _______ process

A

semiconservative

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7
Q

During early interphase, the state of the DNA can be described as

A

A single continuous linear double helix

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8
Q

The step in DNA replication in which the replication proteins open up the double helix and prepare for complementary base-pairing is called

A

Initiation

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9
Q

The step in DNA replication in which two replication forks moving in opposite directions may meet is called

A

Termination

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10
Q

The protein that progressively unwinds DNA ahead of each replication fork is called

A

Helicase

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11
Q

What radiolabelled substance did Hershey and Chase use to label the protein component of the bacteriophage in their study to determine whether protein or DNA was necessary for phage production?

A

Sulfur

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12
Q

Meselson and Stahl relied on equilibrium density gradient centrifugation in a ______ solution to resolve the DNA containing 14N from the DNA containing 15N

A

Cesium chloride

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13
Q

The energy for DNA synthesis comes most directly from

A

dNTP

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14
Q

If chromosomal DNA were single stranded, which of the following would be most reduced compared to a double stranded molecule?

A

Information fidelity (the consistency of sequence between generations)

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15
Q

The enzyme that some organism use to replicate DNA at the 5’ ends of chromosomes is called

A

telomerase

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16
Q

The chromosome can be considered a dynamic organelle for _________ of DNA

A

All of the above
(expression, segregation, replication, packaging)

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17
Q

By weight the chromatin consists roughly of

A

1/3 DNA, 1/3 histones and 1/3 nonhistones

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18
Q

Without __________ regions on the DNA during recombination, gene conversion could not occur

A

heteroduplex

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19
Q

The first level of compaction of DNA consists of

A

DNA winding around histones to form small nucleosomes

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20
Q

Nucleosomal chromatin, with a diameter of 100A, supercoils into a 300A superhelix. The histone that appears to be responsible for this compaction is

A

H1

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21
Q

At what stage of mitosis do we first see a chromosome that is compacted 250-fold over the 40-fold compacted 300A fibre

A

Metaphase

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22
Q

The total compaction of DNA as seen in metaphase chromosomes is approx. _______ fold

A

10,000

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23
Q

With regard to the typical human cell, which of the following appears to be true

A

There are multiple origins of replication that function simultaneously

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24
Q

The 10,000 origins of replication in mammalian calls suggests that concerning origin of replication there is

A

at least one per loop of DNA

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25
Q

Which of the following is not true about DNA polymerase

A

It can replace RNA primer with DNA at the 5’ end

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26
Q

The two chromatids of each replicated chromosome must separate from one another and segregate during

A

Both A and C
(mitosis and meiosis 2)

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27
Q

One of the functions of a centromere is to contribute to proper chromosome segregation. The other function is to

A

hold sister chromatids together

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28
Q

During mitosis, kinetochores develop during

A

prophase

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29
Q

In higher eukaryotes, kinetochores attach to

A

multiple spindle fibers

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30
Q

During development, an XX female embryo will form one of the X chromosomes in each cell into a Barr body. This usually occurs

A

about 2 weeks after zygote formation

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31
Q

recombination occurs during meiotic

A

prophase

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32
Q

The nicking of DNA that initiates recombination during mitosis may be due to all but

A

instruction from normal cell-cycle program

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33
Q

Which of the following statements about the double strand break-repair model is true?

A

Recombination is initiated by the double strand breaks on each of the two sister chromatids

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34
Q

which of these is required for the first strand invasion in the double-strand break repair model?

A

3’ single stand tails on one sister chromatid

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35
Q

Which of the following enzymes is not required for recombination in the double-strand break repair model

A

Double strand recombinase

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36
Q

In the usual flow of genetics information (often called the Central Dogma), which of the following best represents the expression of genes?

A

DNA-RNA-Protein

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37
Q

The scientists credited with postulating the basis for the genetic code are

A

Watson and Crick

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38
Q

which of these is NOT a character of the genetic code

A

There are the same number of codons as there are amino acids

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39
Q

There are __________ usually found in the genetic code

A

1 start codon and 3 stop codons

40
Q

Which of these terms is NOT a stop codon or a nickname for a stop codon

A

emerald

41
Q

Which of these is NOT a step in transcription

A

replication

42
Q

The (expressed) sequences within mRNA that code for gene products are called

A

exons

43
Q

A(n) _________ consists of proteins and small nuclear RNAs forming discrete particles that mediate splicing

A

splicesome

44
Q

Transcription occurs in the _______ and translation occurs in the _________ of eukaryotic cells

A

Nucleous ; cytoplasm

45
Q

In the modification of eukaryotic mRNA, a “cap” consisting of an _________ and a tail consisting of ______ are usually added to the transcript

A

methyl groups, multiple adenines

46
Q

Ribosomes are composed of

A

rRNA and protein

47
Q

Aminoacyl-tRNA sythetase is the enzyme that

A

Adds the appropriate amino acid to an uncharged tRNA

48
Q

A bacterial (prokaryotic) ribosome is composed of _______ subunits

A

30s and 50s

49
Q

Which of these processes are coupled (linked) in prokaryotes but NOT in eukaryotes

A

transcription and translation

50
Q

A mutation that changes a codon sequence, and subsequently changes the amino acid that should have been placed at that point in the polypeptide chain, is called a

A

Missense mutation

51
Q

A mutation that occurs when a base is inserted into or deleted from a DNA sequence, completely alternating the subsequent amino acid sequence is called a

A

Frameshift mutation

52
Q

A tRNA that recognizes a nonsense codon and inserts an amino acid where protein synthesis should have stopped is called a

A

Suppressor tRNA

53
Q

mutations that abolish the function encoded by wild-type allele are known as

A

Null mutations

54
Q

A neomorphic mutation results in an allele that

A

Produces novel proteins or cause inappropriate expression resulting in a new phenotype

55
Q

Assume that for a given gene a mutation creates an allele that functions as dominant negative. The gene codes for a protein that forms a trimer within the cell. If at lease of the subunits has the mutant structure the entire process is inactivated. For a heterozygous individual, what percent of the trimers present in the cell will be inactive

A

12.5%

56
Q

As compared to subunit vaccines, what is the main advantage of “killed whole virus” HIV vaccine under development in Canada

A

jknk

57
Q

What would happen if all of the snRNAs were removed from a cell

A
58
Q

The term mutation refers to

A

A heritable change in the DNA of a cell

59
Q

Replacing a thymine nucleotide with a guanine is an example of a

A

transversion

60
Q

Assume that a wild-type sequence is 5’AGCCTAC3’. indicate the sequence that might be produced by a transversion

A

5’ATCCTAC3’

61
Q

Assume that the mutation rate for a given gene is 5x10^-6 mutations per gene per generation. For that gene how many mutations would be expected if 10 million sperms are examined

A

50

62
Q

Consider the following results. When 50 million sperms were examined for a specific mutation, 100 mutations were found. Indicate the mutation rate for that gene

A

2 x 10^-6

63
Q

The results of the Luria-Delbruck fluctuation experiment indicated that

A

Bacteria become resistant to phage by random spontaneous mutations

64
Q

The hydrolysis of a purine base from the deoxyribose-phophate backbone is called

A

Depurinination

65
Q

UV light is a mutagen that can cause

A

Thymine dimers

66
Q

The heritable disorder fragile X syndrome, a major cause of mental retardation, is caused by

A

Duplication of multiple 3- nucleotide repeats

67
Q

The duplication of the triplet sequence CGG resulting in elongation or breakage of the X chromosome is termed

A

Fragile X syndrome

68
Q

If a base analogue such as 5-bromouracil is used as a mutagen, how many generations will be required to mutate the codon for proline (CCC) into the codon for alanine (GCC)

A

It will not occur

69
Q

Interacting agents such ethidium bromide function as a mutagen

A
70
Q

Assuming that in the organism under study, the DNA polymerase has an error rate of 1 mistake in every 10^6 bases copied. However, the overall mutation rate is much lower. This is most likely because

A

Repair mechanisms correct errors made by the polymerase

71
Q

The genetic condition Xeroderma pigmentosum, which can lead to skin cancer, results from

A

Inability to correct UV induced dimers

72
Q

The consequences to a bacterial cell of a mutation that inactivated the enzyme that methylates the A of the sequence GATC in newly made DNA would be

A

Failure to distinguish old and new DNA during mismatch repair

73
Q

In the Ames test for mutagenicity, rat liver enzymes are included with the compound under tests because

A

Rat liver enzymes may modify or break down some compounds

74
Q

The Ames test for mutagenicity is useful to identify potential carcinogens because

A

Mutagens that affect bacterial DNA are likely to cause human mutation

75
Q

Assume a researcher is studying coat colour in voles. Three stains of white vole have been isolated: milky, blanc, and weiss. White is a recessive train in each strain. Homozygous white voles are obtained for each strain. Consider the following crosses:
milky x blanc = all white
milky x weiss = brown (wild-type)
blanc x weiss = brown (wild-type)
The conclusion most consistent with these results is

A
76
Q

In the human genetic disorder Alkaptonuria, urine turns black because of the presence of homogentisic acid and in individuals with the trait. this is due to

A

Failure of individuals with Alkaptonuria to manufacture enzymes involved in the breakdown of homogentisic acid

77
Q

Indicate the false statement regarding amino acids

A

all correct

78
Q

Choose the condition that involves a defect in an enzyme pathway

A
79
Q

The condition sickle-cell amaemia is due to

A

Substitution of an amino acid

80
Q

Though sickle-cell anaemia is frequently lethal for individuals who are homozygous for the sickle-call allele, natural selection seems to have maintained that allele in certain geographic locations. A likely explination for this observation is that

A

Individuals who are heterozygous for the sickle-cell allele are protected from malaria

81
Q

The structure of a protein that involves the interaction between two distinct polypeptide chains is

A

Quaternary structure

82
Q

The photoreceptor protein rhodopsin

A

is found in rod cells and is sensitive to weak light at many wavelengths

83
Q

Red green colour blindness is more common in males than females because

A

Both the red and the green pigment genes are on the X chromosome

84
Q

Which of the following is used in site-directed mutagenesis

A

Synthetic oligonucleotide

85
Q

How are somatic mutations different from germline mutations

A

Only germline mutations are heritable

86
Q

Which of the following is not considered a chromosomal rearrangement

A

Replication

87
Q

Karyotypes generally remain constant within a species bases

A

Genetic instabilities produced by genomic changes usually are at a selective disadvantage

88
Q

In higher organisms, it is usually difficult to distinguish with genetic analysis small deletions in one gene from

A

point mutations

89
Q

During the pairing of homologues in prophase of meiosis 1, the region of a normal, nondeleted chromosome that has nothing with which to recombine forms a so-called

A

Deletion loop

90
Q

Which of the following does not happen when an intragenic inversion occurs

A

The genes function remains unaffected

91
Q

Robertsonian translocation results from which of the following

A

Breaks at or near the centromeres of two acrocentric chromosomes followed by the reciprocal exchange of broken parts

92
Q

Which of the following would be most helpful in mapping the genes that cause down syndrome

A
93
Q

In terms of evolution, what is the most frequent outcome of repeated duplications of different segments of a species genome

A

Gene families

94
Q

In Drosophila, a gynandroporph, which is composed of equal parts of a male and female tissue, results from

A

An XX female losing one X chromosome during the first mitotic division after fertilization

95
Q

Which of the following causes yellow corn kernals to gain red spots

A

Genetics Final Exam (11 decks)

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