Mitosis and Meiosis

Question 1

What are the 4 phases of cell cycle?

Answer 1

G1, S, G2, M

G1, S, and G2 are the interphase

Question 2

How much time does a cell spend in the interphase?

Answer 2

90%

Question 3

What is a chromosome?

Answer 3

A molecule of DNA and the associated proteins

Question 4

What is a chromatid? What are sister chromatids?

Answer 4

One of the duplicated copies of DNA. Sister chromatids are identical to each other

Question 5

How many chromosomes are in a pair of sister chromatids?

Answer 5

1

Question 6

What is a centromere?

Answer 6

Region of DNA where sister chromatids are attached

Question 7

What is the kinetochore?

Answer 7

The proteins attached to the centromere

Question 8

What is a karyotype? What distinguishes chromosomes?

Answer 8

An image of chromosomes during metaphase. Size, centromere position, secondary constriction, and banding patterns

Question 9

What are the 3 centromere positions?

Answer 9

Metacentric: in the middle
Acrocentric: not in the middle, one arm is shorter than the other
Telocentric: at the telomere

Question 10

What is a secondary constriction?

Answer 10

Places where transcription is occurring, but RNA and proteins aren’t on the karyotype

Question 11

What is mitosis?

Answer 11

An equational division that gives two daughter cells with the same ploidy as the original cell

Question 12

What are the phases of mitosis?

Answer 12

Prophase, metaphase, anaphase, telophase, cytokinesis

Question 13

What happens in prophase of mitosis?

Answer 13

Sister chromatids condense, mitotic spindle begins to form, the mass of chromatin becomes distinguishable chromosomes

Question 14

What occurs in prometaphase of mitosis?

Answer 14

The nuclear envelope breaks apart, sister chromatids finish condensing, mitotic spindle finishes, microtubules attach to the kinetochores

Question 15

What occurs in metaphase of mitosis?

Answer 15

Chromosomes line up along the metaphase plate in the middle of the cell

Question 16

What occurs in anaphase of mitosis?

Answer 16

Sister chromatids separate, the microtubules attached to the kinetochores pull each sister chromatid to opposite ends of the cell

Question 17

What occurs in telophase of mitosis?

Answer 17

Nuclear envelope reforms around each set of chromosomes, chromosomes decondense, mitotic spindle is disassembled

Question 18

What occurs in cytokinesis of mitosis?

Answer 18

The cell membrane pinches inward at the cleavage furrow and the cytoplasm divides

Question 19

What is the ploidy, chromosome number (in human cells), and DNA content in each phase of of the cell cycle of a diploid cell?

Answer 19

G1: 2n, 46, 2c
S: 2n, 46, 4c
G2: 2n, 46, 4c
M: 2n, 46, 2c

Question 20

What is the ploidy, chromosome number (where n=8), and DNA content in each phase of the cell cycle of a haploid cell?

Answer 20

G1: n, 8, c
S: n, 8, 2c
G2: n, 8, 2c
M: n, 8, c

Question 21

What is meiosis?

Answer 21

Two successive rounds of nuclear division, with the first being reductional and second equational

Question 22

Where does meiosis occur? What are the products?

Answer 22

In specialized meiocytes in diploid organisms. Results in 4 gametes or spores that are genetically different from the parent cell

Question 23

What is the difference between meiosis 1 and meiosis 2?

Answer 23

Meiosis 1 is a reductional division, meiosis 2 is an equational division

Question 24

What is a dyad?

Answer 24

A pair of sister chromatids

Question 25

What are phases of meiosis 1?

Answer 25

Prophase 1, metaphase 1, anaphase 1, telophase 1

Question 26

What occurs in prophase 1 of meiosis?

Answer 26

Chromosomes become highly condensed, homologous chromosomes synapse and form a bivalent. Crossing over can occur

Question 27

What are chiasmata?

Answer 27

The visual manifestation of the place where the chromatids cross over

Question 28

What is synapsis?

Answer 28

A very tight association between non-sister chromatids of homologous chromosomes

Question 29

What occurs in metaphase 1 of meiosis?

Answer 29

Bivalents align along the metaphase plate independently of each other and in a random orientation

Question 30

What occurs in anaphase 1 of meiosis ?

Answer 30

Ploidy is reduced, spindle fibres pull apart the bivalent and pull one pair of sister chromatids to each end of the cell

Question 31

What occurs in telophase 1 of meiosis?

Answer 31

Nucleus reforms at each pole, chromosomes decondense. Each new cell has one of the homologous chromosomes

Question 32

How does meiosis 2 proceed? What kind of division occurs?

Answer 32

Proceeds like mitosis. Is an equational division

Question 33

What occurs in prophase 2 of meiosis?

Answer 33

Chromosomes recondense

Question 34

What occurs in metaphase 2 of meiosis?

Answer 34

Chromosomes align along metaphase plate, individually this time

Question 35

What occurs in anaphase 2 of meiosis?

Answer 35

Sister chromatids are pulled apart by the mitotic spindle

Question 36

What occurs in telophase 2 of meiosis?

Answer 36

Chromosomes decondense, nucleus reforms around each set of chromosomes, cytokinesis occurs

Question 37

What is the ploidy, chromosome number (in a 2n=8 cell), and DNA content in each phase of meiosis 1 and 2?

Answer 37

``` Prophase 1: 2n, 8, 4c Metaphase 1: 2n, 8, 4c Anaphase 1: n, 4, 2c Telomere 1: n, 4, 2c Prophase 2: n, 4, 2c Metaphase 2: n, 4, 2c Anaphase 2: n, 4, c Telophase 2: n, 4, c ```