Chapter 3

Question 1

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

Answer 1

M phase

Question 2

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

Answer 2

S phase

Question 3

Mitosis is a process of cell division that results in

Answer 3

two identical daughter cells.

Question 4

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?

Answer 4

centrosome

Question 5

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 ________.

Answer 5

AaBb; AaBb

Question 6

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

Answer 6

disjunction

Question 7

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

Answer 7

46

Question 8

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

Answer 8

23

Question 9

How many sister chromatids are found in a human somatic cell nucleus during mitosis?

Answer 9

92

Question 10

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

Answer 10

meiosis

Question 11

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

Answer 11

diploid

Question 12

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

Answer 12

haploid

Question 13

(mitosis and cytokinesis) follows G2, the last stage of interphase.

Answer 13

M phase

Question 14

The S phase of the cell cycle results in the production of two identical copies of each chromosome, known as __________.

Answer 14

sister chromatids

Question 15

sister chromatids

Answer 15

duplicated copies of a chromosome that remain attached at the centromere.

Question 16

What is the name of the protein that holds sister chromatids together?

Answer 16

cohesion

Question 17

localizes between the sister chromatids and holds them together to resist the pull of the kinetochore microtubules.

Answer 17

cohesion

Question 18

protein structure assembled at the centromere, to which spindle microtubules attach.

Answer 18

kinetochore

Question 19

After chromosomes condense, the ______ is the region where the identical DNA molecules are most tightly attached to each other.

Answer 19

centromere(s)

Question 20

During mitosis, microtubules attach to chromosomes at the

Answer 20

kinetochore

Question 21

In dividing cells, most of the cell’s growth occurs during

Answer 21

interphase

Question 22

The____ is a cell structure consisting of microtubules, which forms during early mitosis and plays a role in cell division

Answer 22

mitotic spindle(s)

Question 23

During interphase, most of the nucleus is filled with a complex of DNA and protein in a dispersed form called

Answer 23

chromatin

Question 24

In most eukaryotes, division of the nucleus is followed by _____, when the rest of the cell divides.

Answer 24

cytokinesis

Question 25

The ______ are the organizing centers for microtubules involved in separating chromosomes during mitosis

Answer 25

centrosome(s)

Question 26

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

Answer 26

prophase I

Question 27

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

Answer 27

synapsis

Question 28

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

Answer 28

chiasmata

Question 29

In meiosis I, the diploid number (2n) of chromosomes is reduced to the haploid number (n) because of the separation of what?

Answer 29

homologous chromosomes

Question 30

In meiosis II, sister chromatids separate and produce four _____ gametes.

Answer 30

haploid

Question 31

sites where DNA strand exchange between non-sister chromatids has occurred

Answer 31

chiasmata

Question 32

During which stage of mitosis and/or meiosis do homologs segregate?

Answer 32

anaphase I of meiosis

Question 33

Independent assortment explains

Answer 33

why a collection of meiotic products that includes gametes of genotype Ab will also include gametes of genotype AB in roughly the same proportion

Question 34

Separation of sister chromatids occurs

Answer 34

at anaphase in mitosis and anaphase II in meiosis

Question 35

Novel combinations of genes can arise from _______.

Answer 35

reciprocal exchange of DNA between homologs during prophase I

Question 36

At the end of the G1 stage, cells have the option of entering which two phases? ___ phase or ___ phase

Answer 36

S, G0

Question 37

Which type of proteins forms complexes with cyclins to regulate progress through cell cycle checkpoints? ``` Which type of proteins forms complexes with cyclins to regulate progress through cell cycle checkpoints? phosphatases ATP synthetases kinases transcription factors ```

Answer 37

kinases

Question 38

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

Answer 38

X-linked inheritance.

Question 39

hemizygous

Answer 39

half zygous

Question 40

males in X-linked genes for Drosophilia are

Answer 40

hemizygous for X-linked genes

Question 41

each division crates two identical daughter cells

Answer 41

mitosis

Question 42

what happens during the G1 phase of interphase

Answer 42

active gene expression and preparation for DNA synthesis

Question 43

what happens during the S phase of interphase

Answer 43

cell replicates its DNA and chromosomes

Question 44

during which stage of interphase does the cell prepare for entry into M phase for cell division?

Answer 44

G2

Question 45

cells rates of transcription and translation are particularly high during this stage of interphase

Answer 45

G1

Question 46

between which two stages of interphase does the G0 stage fall?

Answer 46

between G1 and S

Question 47

what is the G0 stage

Answer 47

nondividning state. cells do not continue through the cell cycle