Exam 3 Flashcards

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1
Q

At what point of the cell cycle would you see a chromosome look like this? (sister chromatids, centromeres on each chromatid)

A

Metaphase (M)

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2
Q

The chromosome begins M phase looking as shown. When does it split?

A

Anaphase (A)

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3
Q

What best describes the kinetochore?

A

Structure composed of several proteins that associate with the centromere region of a chromosome and that can bind to spindle microtubules

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4
Q

From prophase through metaphase of mitosis, each chromosome has ___ DNA molecules, while from anaphase through telophase of mitosis, each chromosome has ___ DNA molecule

A

Two; one

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5
Q

If you were given a slide and told that the cells on it were performing cytokinesis, how would you tell if you had plant cells or animal cells?

A

Look for a cell plate or cleavage furrow

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6
Q

Which comes immediately after S phase in the cell cycle?

A

G2

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7
Q

If a cell that had two copies of each chromosome, but problems with the spindle caused the sister chromatids to remain attached to each other and to only one spindle pole, what cells would result?

A

Cells with 4 copies of each chromosome and 0 copies of each chromosome

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8
Q

You are observing a line of rat cells and see that they repeatedly make mistakes in the cell cycle by going through the G2 checkpoint too early. This could be due to a ___.

A

Problem with the expression of a cyclin

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9
Q

The decline of MPF activity at the end of mitosis is due to

A

The degradation of cyclin

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10
Q

If a cell does not receive a go-ahead signal at G1 checkpoint during cell cycle, name the phase it enters as a nondividing state.

A

G0

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11
Q

Binary fission is more like animal cell division because

A

Bacteria and animals both pinch in to separate cytoplasm into two pieces

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12
Q

Privet shrubs and humans each have diploid number of 46 chromosomes per cell. Why are the two species so dissimilar?

A

The two species have appreciably different genes

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13
Q

Why is it more practical to prepare karyotypes by viewing somatic diploid cells rather than haploid gametes?

A

Both sets of chromosomes, which are present in somatic diploid cells, need to be examined.

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14
Q

Why does sexual reproduction (meiosis) have an advantage over asexual reproduction (mitosis)?

A

Meiosis increases genetic variation among offspring

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15
Q

The mosquito Aedes aegypti has a karyotype of 2n=6. Through independent assortment alone, how many chromosomal combinations can be made during meiosis?

A

8

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16
Q

A human cell containing 22 autosomes and a Y chromosome is

A

a sperm

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17
Q

If the DNA content of a diploid cell in the G1 phase of the cell cycle is x, then the DNA content of the same cell at metaphase of meiosis I will be

A

2x

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18
Q

Which of the following is not a reason that peas were well suited for Mendel’s breeding experiments?

A

Peas have an unusually long generation time

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19
Q

A pea plant is heterozygous at the independent loci for flower color Pp and seed color Yy. What types of gametes can it produce?

A

Four gamete types: pY, py, PY, and Py

20
Q

A cross between homozygous purple-flowered and homozygous white-flowered pea plants results in offspring with purple flowers. This demonstrates

A

dominance

21
Q

The following offspring were observed from many crossing of the same pea plants. (456 purple axial, 152 purple terminal, 140 white axial, 52 white terminal) The alleles for purple, white, axial, and terminal characters are P,p,A,a respectively. What genotypes are the parents?

A

PpAa x PpAa

22
Q

In dragons, wings are a dominant trait, but some dragons are born wingless. If a wingless dragon is crossed with one that is heterozygous, how many of its offspring will be wingless?

A

50%

23
Q

Suppose that Mendel’s hypothesis that inheritance is “particulate” rather than due to blending were wrong. Which observation would he NOT have made?

A

Crossing two-purple flowered heterozygotes produced purple-flowered and white-flowered plants.

24
Q

In peas, the allele for tall stems (T) is dominant to dwarf stems (t), and axial flowers (A) is dominant to terminal flowers (a). A plant of unknown genotype with tall stems and axial flowers is crossed with a plant with dwarf stems and terminal flowers. Among the offspring are 38 plants with tall stems and axial flowers, and 36 plants with tall stems and terminal flowers. What is the previously unknown genotype?

A

TTAa

25
Q

Morgan and his colleagues worked out a set of symbols to represent fly genotypes. Which of the following is representative?

A

Xw+ or Xw

26
Q

In some species of Drosphilia, there are genes on the Y chromosome that are not on the X chromosome. Imagine that a new allele arises on the Y chromosome and reduces size by half of individuals with the new allele. Which of the following statements is accurate with regard to this situation?

A

This allele is passed to all male but no female offspring of a male with the allele.

27
Q

In cats, an X-linked gene affects coat color. The O allele produces an enzyme that converts eumelanin, a black/brown pigment into phaeomelanin, an orange pigment. The o allele is recessive to O and produces a defective enzyme, one that does not convert eumelanin into phaeomelanin. Which of the following statements is accurate?

A

The phenotype of o-Y males is black/brown because the nonfunctional allele o does not convert eumelanin into phaeomelanin.

28
Q

Genes which tend to be inherited together are called

A

Linked genes

29
Q

Who conducted the X-ray diffraction studies that were key to the discovery of the structure of DNA?

A

Franklin

30
Q

What enzyme compensates for replication-associated shortening of linear chromosomes?

A

Telomerase

31
Q

Which of the following results from Griffith’s experiment is an example of transformation?

A

Mouse dies after being injected with a mixture of heat-killed S and R living cells

32
Q

Suppose a double-stranded DNA molecule was shown to have 22% guanine bases. What would be the expected percentage of adenine bases in the molecule?

A

28%

33
Q

Consider the replication bubble diagramed (5’-L-M-3’ / 3’-N-O-5’). Which letters represent leading strands?

A

L and O

34
Q

Consider the replication bubble diagramed (5’-L-M-3’ / 3’-N-O-5’). Which letters represents places where one could find Okazaki fragments?

A

M and N

35
Q

In Meselson and Stahl’s experiment proving semiconservative DNA replication, they started with bacteria grown in a heavy isotope of nitrogen and then switched them to a light isotope. They then observed the DNA density after one and two rounds of replication. What was the result after one round of replication?

A

All hybrid DNA

35
Q

Imagine a bacterial replication fork. Synthesis of which new strand(s) would be affected by mutations in the enzyme DNA polymerase III?

A

Both leading and lagging strands

36
Q

In Meselson and Stahl’s experiment proving semiconservative DNA replication, they started with bacteria growth in a heavy isotope of nitrogen and then switched them to a light isotope. They then observed the DNA density after one and two rounds of replication. What was the result after two rounds of replication?

A

Equal amounts of light and hybrid DNA

37
Q

Which of the following terms does not directly pertain to translation?

A

DNA

38
Q

The temple strand of a given gene includes the sequence 3’-GCCACGTATCA-5’. What is the sequence of the nontemplate strand?

A

5’-CGGTGCATAGT-3’

39
Q

Which of the following is the best example of gene expression?

A

Mouse fur color results from pigment formed by gene-encoded enzymes

40
Q

In the transcription process, in which process order (1,2,3) does the RNA polymerase bind to the promoter, in which is the RNA transcript released, and in which is the RNA transcript extended?

A

1,3,2

41
Q

Which of the following components does not form part of the transcription initiation complex at a eukaryotic promoter?

A

Transfer RNA

42
Q

Aminoacyl-tRNA synthetase is an enzyme whose function is to___.

A

Link tRNA to its corresponding amino acid

43
Q

Which of the following is a modification made to eukaryotic mRNA before it is exported to the cytosol?

A

All of the above (5’ end is capped, poly-A tail added to 3’ end, introns are removed, exons are joined together)

44
Q

Which of the following statements comparing prokaryotic and eukaryotic transcription is not true?

A

RNA polymerase requires a primer in bacteria; in eukaryotes , it does not

45
Q

The nontemplate strand of a portion of a gene reads 5’-TTCACTGGTTCA. What is the sequence of the resulting transcript for this portion?

A

5’-UUCACUGGUUCA

46
Q
A