Deck 3: Cell Division and Chromosome Heredity

Question 1

If you mutate the gene encoding a Cdk such that Cdk protein product cannot bind to cyclin, what effect would you expect to see?

A)Cdk will be unaffected.
B)The cell cycle will be up-regulated, and the cells will proliferate.
C)Cdk will be inactive, so the target proteins will not be phosphorylated.
D)Cdk will be constitutively active, so the cell cycle will be unchecked.
E)Cdk will phosphorylate its target proteins regardless of the cell cycle.

Answer 1

C

Question 2

After which stage or phase of the cell cycle does cytokinesis occur?

A)M phase
B)G₁
C)G₂
D)S
E)G₀

Answer 2

A

Question 3

How do protein kinases generally activate their target proteins?

A)The process of phosphorylation causes the target proteins to change conformation.
B)The kinases bind to target proteins directly, forming a complex that activates the proteins and lets them change conformation.
C)Kinase concentrations vary during the cell cycle, so that proteins are activated only when kinase levels are high.
D)Kinases bind to target proteins and inactivate them, so kinase levels must drop for target protein activation.
E)The process of dephosphorylation causes the target proteins to change conformation.

Answer 3

A

Question 4

A dihybrid has the genotype AaBb. After a normal mitotic division into two daughters cells, one daughter cell will have the genotype _____________ and the other will have the genotype ______________.

A)Aa; Bb
B)AaBb; AaBb
C)AB; ab
D)Ab; aB
E)AABB; aabb

Question 5

The separation of sister chromatids during anaphase I of mitosis is known as chromosome __________.

A)cytokinesis
B)karyokinesis
C)crossing over
D)synapsis
E)disjunction

Question 6

Vinblastine is a commonly used chemotherapy drug that acts by interfering with the assembly of microtubules. How does it likely target cancer cells?

A)by suppressing cyclins
B)by inhibiting protein kinases
C)by inhibiting DNA synthesis
D)by denaturing myosin and preventing the cleavage furrow from forming
E)by disrupting mitotic spindle formation

Question 7

You discover a new species of snail, Biologica terificia, and find that its haploid number is 4 (n = 4). The somatic cells of Biologica terificia are diploid. How many chromosomes are in a somatic cell of the snail in G₁ phase?

A)4
B)8
C)16
D)too many to count

Question 8

How many DNA molecules are in a somatic cell of the snail in G₂ phase?

A)4
B)8
C)16
D)too many to count

Question 9

Scientists isolate two different cells from the same organism at different points in the cell cycle. Cell A has 1.5 times the DNA content of cell B. Which of the following is true?

A)cell A is in G₁ phase; cell B is in G₂ phase
B)cell B is in G₁ phase; cell A is in G₁ phase
C)cell A is in S phase; cell B is in G₁ phase
D)cell B is in S phase; cell A is in G₁ phase
E)cell A is in S phase; cell B is in G₂ phase

Question 10

Tumor suppressors are genes that __________.

A)promote advancement of the cell cycle
B)phosphorylate proteins involved in the cell cycle
C)block progression of the cell cycle
D)prevent apoptosis in normal cells
E)activate proto-oncogenes

Question 11

Mutations that inhibit Rb gene expression will have what effect on cell proliferation?

A)Cells will proliferate less, even if excess growth factors are present.
B)Cells will proliferate less because growth factors are absent.
C)Cells will proliferate more because growth factors are produced in excess.
D)Cells will proliferate more, regardless of growth factor concentration.
E)There will be no effect on cell proliferation; only apoptosis occurs.

Question 12

During which stage or phase of the cell cycle does the cell actively transcribe and translate at the highest rate all the protein products necessary for normal cellular structure and function?

A)M phase
B)G₁
C)G₂
D)S
E)metaphase

Question 13

During mitotic cell division, if chromosomal material is improperly divided between the two daughter cells, one cell could receive three copies of a chromosome, and the other cell could receive only one. This is likely due to a defect in which process?

A)cytokinesis
B)karyokinesis
C)crossing over
D)synapsis
E)homologous recombination

Question 14

Certain kinds of cells (e.g., some cells in the eyes and bones)mature and differentiate into a state in which they have a specialized function but do not divide or progress through the cell cycle. These cells are "stuck" in which stage?

A)M phase
B)G₁
C)G₂
D)S
E)G₀

Question 15

The accompanying figure represents a chromosome at metaphase of mitosis. How many DNA molecules are present in this chromosome?

A)one
B)two
C)four
D)more than four
E)impossible to determine

Question 16

During which stage or phase of the cell cycle does the cell replicate its chromosomes?

A)M phase
B)G₁
C)G₂
D)S
E)G₀

Question 17

Mitosis is a process of cell division that results in __________.

A)two unique daughter cells
B)four unique daughter cells
C)two identical daughter cells
D)three identical daughter cells
E)four identical daughter cells

Question 18

Which organelle migrates during M phase to form the two opposite poles of the dividing cell and acts as the source of the spindle fiber microtubules?

A)centromere
B)kinetochore
C)centrosome
D)chiasmata
E)chromosome

Question 19

During which cell cycle phase(s)are chromosomes composed of two DNA molecules?

A)G₂
B)G₁
C)anaphase
D)Answers (A)and (B)are correct.
E)Answers (A), (B), and (C)are correct.

Question 20

Which structure is responsible for chromosome movement during cell division?

A)synaptonemal complex
B)kinetochore microtubules
C)metaphase plate
D)nuclear envelope
E)cell membrane

Question 21

If a trait is X-linked dominant, who would express the trait?

A)females homozygous for the dominant allele and males hemizygous for the recessive allele
B)heterozygous females and males hemizygous for the dominant allele
C)females homozygous for the recessive allele and males hemizygous for the recessive allele
D)females homozygous for the recessive allele and males hemizygous for the dominant allele
E)significantly more females than males

Question 22

Bridges showed that sex determination in Drosophila meant that __________.

A)females were XX or XXX, and males were XY or XXY
B)females were XX, and males were XY
C)females were XX, and males were XY or XO
D)females were XX or XXX, and males were XY or XO
E)females were XX or XO, and males were XY or XXY

Question 23

How many chromosomes are found in a human somatic cell nucleus?

Question 24

During meiosis I, when does homologous chromosome pairing and recombination occur?

A)prophase I
B)pro-metaphase I
C)metaphase I
D)anaphase I
E)telophase I

Question 25

Contact points between nonsister chromatids that mark the locations of DNA-strand exchange are called __________.

A)synaptonemal complexes
B)metaphase plates
C)chiasmata
D)kinetochores
E)centrosomes

Question 26

How many homologous pairs of chromosomes are found in a human somatic cell nucleus?

Question 27

What insight did Nettie Stevens's studies of the beetle Tenebrio molitor provide about the chromosome theory of inheritance?

A)Genes are located on chromosomes.
B)The number of autosomal chromosomes varied between gametes.
C)Crossing over occurs between homologous chromosomes.
D)Sex is determined by the presence of an X or Y chromosome in the male gamete.
E)Chromosomes assort independently into the haploid gametes.

Question 28

What dosage compensation mechanism is employed by female placental mammals?

A)synteny
B)Y-inactivation
C)X-inactivation
D)X nondisjunction
E)X chromosome crossing over

Question 29

Red-green color blindness is an X-linked recessive disorder. A woman with normal vision whose father was colorblind has children with a man with normal color vision. What is the probability that their first child will be colorblind?

A)1/4
B)1/2
C)3/4
D)0
E)1

Question 30

Which of the following represents the contents of a cell in G₂ phase (before cell division begins)?

A)Cell G
B)Cell H
C)Cell K
D)Cell M
E)Cell P

Question 31

What process is used to make mature germ-line cells, or gametes?

Question 32

WT yeast (TRP+)can synthesize the amino acid tryptophan and can grow on media plates lacking tryptophan. In contrast, mutant alleles (trp-)block tryptophan synthesis and result in an inability of mutant strains to grow on media lacking tryptophan. A diploid yeast was made through the cross MATa ADE+ × MATα ade-. Meiosis was induced in the diploid strain to produce an ascus with four haploid spores, which were separated and grown on plates lacking tryptophan. How many spores are expected to grow into colonies on the plate?

A)0
B)1
C)2
D)3
E)4

Question 33

If a trait is X-linked recessive, who would express the trait?

A)females homozygous for the dominant allele and males hemizygous for the recessive allele
B)heterozygous females and males hemizygous for the dominant allele
C)females homozygous for the recessive allele and males hemizygous for the recessive allele
D)females homozygous for the recessive allele and males hemizygous for the dominant allele
E)the same proportions of females and males

Question 34

How many total chromatids are found in a human somatic cell nucleus during G₂ phase?

Question 35

The binding of nonsister chromatids by a synaptonemal complex draws the homologs into close contact so that what process can occur?

A)cytokinesis
B)karyokinesis
C)independent assortment
D)synapsis
E)disjunction

Question 36

Which of the following cells could be created from a mitotic division but would not be created during a normal meiosis?

A)Cell G
B)Cell H
C)Cell K
D)Cell M
E)Cell P

Question 37

A dihybrid has the genotype AaBb. The diagram depicts the chromosome composition of different cells from the animal. Which of the cells could represent a mature gamete?

A)Cell G
B)Cell H
C)Cell K
D)Cell M
E)Cell P

Question 38

Morgan's analysis of a white-eyed male Drosophila mutation helped explain __________.

A)autosomal dominance
B)random mutation
C)crossing over
D)independent assortment
E)X-linked inheritance

Question 39

A pure-breeding female fruit fly with a yellow body is crossed to a pure-breeding male fruit fly with a gray body. All female offspring from the cross have gray bodies and all males have yellow bodies. Body color is likely a(n)__________trait, and the gray allele is ________.

A)Autosomal; dominant
B)Autosomal; recessive
C)X-linked; dominant
D)X-linked; recessive

Question 40

What is the short segment of the cell cycle during which genetic material is partitioned equally to two daughter cells?

Question 41

Protein kinases help phosphorylate target proteins, but they are present in relatively constant concentrations throughout the cell cycle. Which proteins, which vary during the cell cycle, form a complex with the kinases to activate them only at specific times?

Question 42

Microtubules are polar, having a plus-end and a minus-end. Which end is anchored at the centrosome?

Question 43

What separates in meiosis I to reduce the diploid number (2n)of chromosomes to the haploid number (n)?

Question 44

What is the mammalian transcription factor that elicits a cascade of gene transcription and developmental events that ultimately produce male internal and external structures?

Question 45

Why are chromosomes more easily visible under the microscope during metaphase as compared to G₂ phase?

Question 46

According to Bridges's proposal, exceptional phenotypes and unusual karyotypes were the result of rare mistakes in meiosis caused by the failure of X chromosomes to separate properly in either the first or second meiotic division in females. What term is used in referring to this phenomenon?

Question 47

At the end of meiosis II, what is produced?

Question 48

The five substages of M phase are designed to accomplish two main goals: equal partitioning between the two cells of chromosomal material and of cytoplasmic contents. What are these two processes called?

Question 49

If a cell begins to divide rapidly (as often seen in wound repair), what would you expect to happen to the G₁ phase?

Question 50

Of the trillions of cells in the human body, most are ________, the cells that form organs and tissues.

Question 51

Females have two copies of the X chromosome, so they can be homozygous or heterozygous for any genes found on the X chromosome. Males have only one copy of the X chromosome. What term is used to describe this inheritance state?

Question 52

Which protein assures that sister chromatids of each chromosome remain firmly joined and can resist the pull of the kinetochore microtubules?

Question 53

The gametes of the two sexes are often dramatically different in size and morphology. If both gametes have a haploid nuclei, then what do female gametes contain more of?

Question 54

A cell in G₁ phase has the option of entering which two phases?

Question 55

The number of occurrences of which event correlates closely with the number of recombination nodules along each homologous chromosome arm?

Question 56

The ________ varies among species (each species has its characteristic number of pairs)and is identified nonspecifically as 2n.

Question 57

When cyclin D1 is expressed in normal levels, it stimulates the cell cycle. If overexpressed, it can promote cancer by allowing cells to overproliferate. The normal cyclin D1 gene, which has the potential to cause cancer if mutated and/or overexpressed, is known as what?

Question 58

The ________ number, or n, is the number of chromosomes contained in the nuclei of gametes, the nonsomatic cells.

Question 59

Single-celled eukaryotes can survive and reproduce in both haploid and diploid forms. Yeast spend most of their life cycle and actively reproduce in which form?

Question 60

Which term describes any mechanism that compensates for differences in the number of copies of genes due to the different chromosome constitutions of males and females?

Question 61

In meiosis, interphase is followed by two successive rounds of cell division, meiosis I and II. Meiosis results in four haploid daughter cells because there is no ________ between these two meiotic cell divisions.

Question 62

What is the difference between cytokinesis and karyokinesis? Which process needs to be more precise for accurate cell division?

Question 63

How do cyclin-dependent kinases help regulate the cell cycle?

Question 64

Synapsis initiates formation of a protein bridge called the synaptonemal complex, a tri-layer protein structure that maintains synapsis by tightly binding ________ of homologous chromosomes to one another.

Question 65

Describe how Mendel's two laws are illustrated by the movement of chromosomes in meiosis.

Question 66

What are three important differences between mitosis and meiosis I?

Question 67

An individual is heterozygous for a gene at a specific locus. Sister chromatids will have _______ (the same form/different form)of alleles at that locus after S phase.

Question 68

Describe how microtubules and cohesion work together to align the chromosomes along the metaphase plate during the process of sister chromatid cohesion.

Question 69

Which meiotic division(s)reduce(s)chromosome number (i.e., meiosis I, meiosis II, or both)? Explain your answer.