Lecture 8: Mitosis and Meiosis

Question 1

In eukaryotes, the hereditary information within the nucleus is distributed among individuals called?

Answer 1

linear DNA molecules

Question 2

What are three things DNA molecules can do?

Answer 2

1. combine with proteins that stabilize the DNA molecules
2. assist in packaging DNA during cell division
3. influence the expression of individual genes

Question 3

In a cell, each chromosome is composed of one what?

Answer 3

DNA molecule an its associated proteins

Question 4

What is the chromosome complement?

Answer 4

the complete set of chromosomes of eukaryotic organism

Question 5

The nucleus of each somatic contains a ___ number of chromosomes typical of the particular species

Answer 5

fixed

Question 6

T or F: the number of chromosomes vary tremendously among species and have little relationship to the complexity of the organism

Answer 6

True

Question 7

What phases are in interphase?

Answer 7

G1, S, G2

Question 8

What does G1 stand for, and what is a basic description?

Answer 8

primary growth phase, and it is the longest phase. It also stands for gap phase 1

Question 9

What does S phase stand for and what is a basic description?

Answer 9

Synthesis, and replication of DNA

Question 10

What does G2 phase stand for and what is a basic description?

Answer 10

Gap phase 2, organelles replicate, microtubules organize

Question 11

How many phases is mitosis divided into?

Answer 11

5

Question 12

What is cytokinesis?

Answer 12

the separation into 2 new cells

Question 13

T or F: the time it takes to complete a cell cycle varies greatly?

Answer 13

True

Question 14

In G2, what are three things besides the basic description that occurs?

Answer 14

1. chromosomes coil more tightly using motor proteins
   2.centrioles replicate
2. tubulin synthesis

Question 15

What are centromeres?

Answer 15

the point of constriction

Question 16

T or F: each sister chromatid has a centromere

Answer 16

True

Question 17

How do chromatids stay attached at the centromere?

Answer 17

by cohesin

Question 18

What protein replaces cohesins?

Answer 18

condensins (in multicellular animals)

Question 19

What are the five phases of mitosis?

Answer 19

1. prophase
2. prometaphase
3. metaphase
4. anaphase
5. telophase

Question 20

What continues throughout prophase?

Answer 20

condensation

Question 21

When does the spindle apparatus assemble?

Answer 21

prophase

Question 22

When does the nuclear envelope breaks down?

Answer 22

prophase

Question 23

When do individual condensed chromosomes first become visible with the light microscope?

Answer 23

prophase

Question 24

When does prometaphase occur?

Answer 24

The transition occurs after disassembly of nuclear envelope

Question 25

What is called when chromosomes begin to move to center of cell, and what phase is it in?

Answer 25

congression, prometaphase

Question 26

What is metaphase?

Answer 26

The alignment of chromosomes along the metaphase plate

Question 27

In what phase do the centromeres begin to split, and cohesin proteins from all chromosomes is removed, and sister chromatids are pulled to opposite poles?

Answer 27

Anaphase

Question 28

What is anaphase A?

Answer 28

kinetochores pulled toward poles

Question 29

What is anaphase B?

Answer 29

the poles move apart

Question 30

In what phase does the spindle apparatus dissambles and the nuclear envelope forms around each set of sister chromatids?

Answer 30

Telophase

Question 31

In what phase are the sister chromatids called chromosomes?

Answer 31

Telophase

Question 32

When do the chromosomes begin to uncoil?

Answer 32

telophase

Question 33

What is the sexual life cycle composed of?

Answer 33

meiosis and fertilization

Question 34

When does the nucleolus reappear in each new nucleus?

Answer 34

telophase

Question 35

What cells are diploid?

Answer 35

somatic

Question 36

What cells are haploid?

Answer 36

gametes

Question 37

What do offspring inherit from 2 parents?

Answer 37

genetic material

Question 38

In most animals, with sexual reproduction, what state dominates?

Answer 38

diploid state

Question 39

Single - cell diploid zygote undergoes mitosis to produce___ cells?

Answer 39

somatic

Question 40

Some diploid cells undergo meiosis to produce ____ gametes

Answer 40

haploid

Question 41

How many rounds of division are in Meiosis?

Answer 41

two rounds

Question 42

What is synapsis?

Answer 42

It occurs in early prophase I, and homologous chromosomes become closely associated, and it includes formation of synaptonemal complexes

Question 43

What are synaptonemal complexes also called?

Answer 43

tetrads or bivalents

Question 44

When does crossing over?

Answer 44

prophase I

Question 45

What are the sites for crossing over called?

Answer 45

chiasmata

Question 46

What is the first meiotic division termed?

Answer 46

reduction division

Question 47

T or F: No DNA replication between meiotic divisions

Answer 47

True

Question 48

What does the first meiotic division result in?

Answer 48

daughter cells that contain one homologue from each chromosome pair

Question 49

What does the second meiotic division result in?

Answer 49

it separates the sister chromatids for each homologue

Question 50

What is crossing over?

Answer 50

the genetic recombination between non-sister chromatids

Question 51

T or F: after crossing over, alleles of genes that were formerly on separate homologues can now be found on the same homologue

Answer 51

True

Question 52

What happens in Metaphase 1?

Answer 52

1.paired homologues locked together following crossing over, 2. microtubules from opposite poles attach to each homologue 3. homologues are aligned at the metaphase plate side-by-side

Question 53

T or F: the orientation of each pair of homologues on the spindle is random

Answer 53

True

Question 54

In what phase do 1. microtubules of the spindle shorten (chiasmata break) 2. homologues are separated from each other and move to opposite poles (sister chromatids remain attached at centromeres) 3. each poles has a complete haploid set of chromosomes 4. independent assortment of maternal and paternal chromosomes

Answer 54

anaphase 1

Question 55

In what phase does the nuclear envelope re-forms around each daughter nucleus

Answer 55

telophase 1

Question 56

What happens in prophase II?

Answer 56

nuclear envelopes dissolve and new spindle apparatus forms

Question 57

What happens in metaphase II?

Answer 57

chromosomes align on metaphase plate

Question 58

What happens in anaphase II?

Answer 58

sister chromatids are separated from each other

Question 59

What happens in telophase II?

Answer 59

nuclear envelope re-forms around 4 sets of daughter chromosomes; cytokinesis follows

Question 60

What is the final result of meiosis?

Answer 60

four cells containing haploid sets of chromosomes

Question 61

What is nondisjunction?

Answer 61

failure of chromosomes to move to opposite poles during meiotic division

Question 62

What are aneuploid gametes?

Answer 62

gametes with missing or extra chromosomes

Question 63

What are the two key differences between meiosis and mitosis?

Answer 63

1. maintenance of sister chromatid cohesion at the centromere during all of meiosis I 2. loss of cohesion from the chromosome arms during anaphase I

Question 64

T or F: Sister kinetochores attach to the same pole during meiosis I

Answer 64

True

Question 65

T or F: Meiosis produces cells that are not indentical

Answer 65

True

Question 66

How does meiosis produce cells that are not identical?

Answer 66

random orientation in first division and crossing over