Week 5_Cytokinesis/Meiosis

Question 1

what is cytokinesis?

Answer 1

the process of dividing 1 cell into 2

Question 2

how does cytokinesis occur in animal cells?

Answer 2

use a contractile ring composed of

actin microfilaments and myosin motor proteins –> contract rapidly to “pinch” cell into 2 (cleavage furrow)

Question 3

how does cytokinesis occur in plant cells?

Answer 3

(1) vesicles (membrane-bound delivery vehicles) accumulate in the middle of the cell

(2) vesicles bring the necessary material to form a temporary structure called a cell plate

(3) the cell plate goes thru a series of biochemical changes and becomes the cell wall

Question 4

in G1, there are ___, ___-chromatid chromosomes (in human cells that are not dividing

Answer 4

46 one-chromatid chromosomes

Question 5

in G1, the chromosomes are in pairs: ___

Answer 5

1 from Mom, 1 from Dad

Question 6

each pair of chromosomes are referred to as ___ or ___. They are very similar but ___

Answer 6

homologs or homologous chromosomes

slightly different

Question 7

what are homologous chromosomes?

Answer 7

contain the same genes but have slightly different DNA sequences

Question 8

before DNA replication, each homolog has ___

Answer 8

1 chromatid

Question 9

after DNA replication, each homolog has ___

Answer 9

2 chromatids

Question 10

what is ploidy?

Answer 10

how many homologs of each chromosome are in a cell

Question 11

what is diploid?

Answer 11

has 2 homologs of each chromosome, one from each parent

2n

Question 12

what is haploid?

Answer 12

have 1 homolog of each chromosome

n or 1n

Question 13

what is polyploid?

Answer 13

have 3 or more homologs of each chromosome

Question 14

mitosis vs meiosis:

what is mitosis?

Answer 14

a eukaryotic cell divides and makes a clone (a copy) of itself

each new cell has the same # of chromosomes as the original cell

Question 15

mitosis vs meiosis?

what is meiosis?

Answer 15

a eukaryotic cell divides

each new cell has 1/2 the # of chromosomes as the original cell

Question 16

why would a eukaryote go thru meiosis?

Answer 16

reproduction

Question 17

meiosis enables ___

Answer 17

reproduction

Question 18

what are the chromosomes like before meiosis in adults?

Answer 18

diploid

46, 1-chromatid chromosomes

Question 19

what are the chromosomes like after meiosis?

Answer 19

haploid

23, 1-chromatid chromosomes

Question 20

what are the chromosomes like in the zygote (1-celled embryo)?

Answer 20

diploid

46, 1-chromatid chromosomes

Question 21

what is gametogenesis?

Answer 21

making sperm and egg cells

Question 22

spermatogenesis results in…

Answer 22

4 viable haploid sperm cells

Question 23

describe the process of spermatogenesis

Answer 23

1, primary spermatocyte (diploid) undergoes meiosis to become

4, mature sperm cells (haploid)

Question 24

oogenesis results in…

Answer 24

1 viable egg cell and 3 nonviable egg cells called polar bodies (all haploid)

Question 25

describe the process of oogenesis

Answer 25

1, primary oocyte (diploid) undergoes meiosis to become

1 viable egg cell and 3 nonviable egg cells called polar bodies (all haploid)

Question 26

give an overview of meiosis I

Answer 26

cell in G1:
- four, 1-chromatid chromosomes
- 1 diploid cell

S-phase:
- four, 2-chromatid chromosomes
- 1, diploid cell

Meiosis I:
- the first of 2 cell divisions
- homologous pairs segregate into different cells
- 2 haploid cells

Question 27

what is the result of Meiosis I?

Answer 27

there are 2 cells each with two, 2-chromatid chromosomes

Question 28

because the chromosomes # is less, MI is called a ___

Answer 28

reduction division

Question 29

after Meiosis I, there are…

Answer 29

2 cells each with two, 2-chromatid chromosomes

these cells are haploid

Question 30

what occurs during Meiosis II?

Answer 30

chromatids separate and segregate into different cells

Question 31

after Meiosis II:

Answer 31

4 cells each with two, 1-chromatid chromosomes

haploid