Chapter 3 - Cell Division/ Chromosomes

Question 1

meiosis I

Answer 1

homologous chromosomes separate from one another, reducing the diploid number of chromosomes (2n) to the haploid number (n)

Question 2

meiosis II

Answer 2

sister chromatids separate to produce haploid gametes, each with one chromosome of the diploid pair

Question 3

purpose of mitosis

Answer 3

to produce genetically identical cells for growth and maintenance

Question 4

product of mitosis

Answer 4

2 genetically identical diploid daughter cells that continue to divide by mitosis

Question 5

purpose of meiosis

Answer 5

to produce gametes for sexual reproduction that are genetically different

Question 6

product of meiosis

Answer 6

4 genetically different haploid cells that mature to form gametes and unite to form diploid zygotes

Question 7

3 important events in meiosis I

Answer 7

1. homologous chromosome pairing
2. crossing over between homologous chromosomes
3. segregation of homologous chromosomes that reduce chromosome to the haploid number

Question 8

4 stages of meiosis I

Answer 8

1. prophase I
2. metaphase I
3. anaphase I
4. telophase I

Question 9

stages of prophase I of meiosis I

Answer 9

1. leptotene
2. zygotene
3. pachytene
4. diplotene

Question 10

happenings of prophase I of meiosis

Answer 10

homologous chromosome pairing and recombination (crossing over) takes place during pachytene stage

Question 11

happenings of metaphase I of meiosis I

Answer 11

tetrads align along metaphase plate

this is where independent assortment occurs

Question 12

happenings of anaphase I or meiosis I

Answer 12

homologous chromosomes separate and sister chromatids remain attached

Question 13

happenings of telophase I and cytokinesis (end of meiosis I)

Answer 13

nuclear membrane reforms to create 2 new cells each with a haploid set of chromosomes

Question 14

happenings of prophase II of meiosis II

Answer 14

nuclear envelope breaks down and centrosomes appear

Question 15

happenings of metaphase II of meiosis II

Answer 15

chromosomes align along the metaphase plate

Question 16

happenings of anaphase II of meiosis II

Answer 16

sister chromatids separate

Question 17

happenings of telophase II and cytokinesis (end of meiosis II)

Answer 17

nuclear envelope reforms to create 4 new genetically different haploid cells

Question 18

synapsis

Answer 18

alignment of homologous chromosomes pairs in zygotene of prophase I

Question 19

3 stages of interphase of mitosis

Answer 19

1. G1 - cell expresses its genetic info
2. S - replicates its chromosomes; results in double the amount of DNA and the creation of 2 sister chromatids for each chromosome
3. G2 - prepares for entry into M phase

Question 20

5 stages of M phase

Answer 20

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

Question 21

major difference between meiosis and mitosis

Answer 21

in meiosis, the sister chromatids stay attached

Question 22

hemizygous

Answer 22

referring to the genotype of males that carry a single copy of each x-linked gene

Question 23

barr body

Answer 23

a condensed and mostly inactivated X chromosome

Question 24

lyon hypothesis

Answer 24

an X is randomly chosen in each cell for inactivation early in development

Question 25

nondisjunction

Answer 25

the failure of homolog or sister chromatid separation during cell divisions; results in nuclei with the wrong number of chromosomes