11.3 meiotic cell division

Question 1

Mitotic cell division is the basis for

Answer 1

sexual reproduction

Question 2

A new organism produced by sexual reproduction has the same amount of chromosomes as its parents since…..

Answer 2

the egg and the sperm each contain half the number of chromosomes as the diploid parent.

Question 3

what are gametes produced by?

Answer 3

meiotic cell division

Question 4

How many rounds of nuclear division occur in meiotic division?

Answer 4

2 rounds of nuclear division

Question 5

How does meiotic cell division make sexual reproduction possible?

Answer 5

by producing haploid gametes

Question 6

the cells produces by meiosis are

Answer 6

haploid eggs and and sperm that fuse in sexual reproduction

Question 7

What are the 2 cell divisions called?

Answer 7

meiosis 1 and meiosis 2 occurring one after another

Question 8

What occurs during prophase 1 of meiosis

Answer 8

1. Chromosomes become visible as thin threads. DNA replication is already complete.
2. homologous chromosomes continue to condense and undergo synapsis
3. Each pair of chromosomes forms a bivalent
4. chromosomes continue to shorten and thicken the chiasmata between the non-sister chromatids become apparent
5. nuclear envelope begins to break down

Question 9

What is an important step that is unique to meiosis?

Answer 9

homologous chromosomes pair with each other lying side by side in a process called synapsis

Question 10

How do Y and X chromosomes pair during synapse?

Answer 10

at the tip where the DNA sequence is almost identical

Question 11

what is a bivalent?

Answer 11

two pairs of sister chromatids aligned along their length.

Question 12

What do non-sister chromatids result from?

Answer 12

the replication of homologous chromosomes so they have the same set of genes in the same order but are not genetically identical

Question 13

what are the differences between mitosis and meiosis?

Answer 13

mitosis
- 2 daughter cells
- daughter cells are genetically identical to each other and parent cell
-daughter cell is diploid
meiosis
-4 daughter cells
-daughter cels are genetically different from each other
- daughters contain 1/2 amount of genetic material from parent
-haploid daughter cells

Question 14

Meiosis 1 and Meiosis 2 are also known as

Answer 14

reduction division and equational division

Question 15

What are chiasmata?

Answer 15

cross like structures with in the bivalent.

Question 16

What is the crossover?

Answer 16

the physical breakage and reunion between non-sister chromosomes.

Question 17

what is the average number of chiasmata per meiosis in humans?

Answer 17

50-60

Question 18

What is another role of the chiasma?

Answer 18

holding bivalents together while they become properly orientated in the centre of the cell during metaphase.

Question 19

What occurs in pro metaphase 1?

Answer 19

the nuclear envelope begins to disappear, and the meiotic spindle begins to form.

Question 20

What occurs during metaphase 1?

Answer 20

bivalents move to a line in the centre. orientation of bivalents is random but a couple set of chromosomes is pulled to opposite poles.

Question 21

What occurs during anaphase 1?

Answer 21

the two homologous chromosomes of each bivalent separate as they are pulled in opposite directions. the centromeres don’t split and the 2 chromatids that make up each chromosome remain together.

Question 22

since only 1 homologous chromosome goes to each pole, how many chromosomes are at the end of the poles at the end of meiosis 1?

Answer 22

23

Question 23

What occurs in telophase 1?

Answer 23

chromosomes slightly uncoil and nuclear envelope briefly reappears. The cytoplasm divides producing 2 separate cells ready for prophase 2.

Question 24

is there DNA synthesis between the two meiotic divisions?

Answer 24

no

Question 25

What occurs during prophase 2 of metaphase?

Answer 25

the nuclear envelope breaks down and the chromosomes condense. the nuclei have a haploid number of chromosomes. the spindle begins to set up.

Question 26

What occurs in pro metaphase 2?

Answer 26

the spindles attache to opposite sister kinetochores on chromosomes.

Question 27

What occurs in metaphase 2?

Answer 27

Chromosomes align in the centre of the cell and the sister chromatids are bi-oriented.

Question 28

What occurs during anaphase 2?

Answer 28

the centromere of each chromosome splits and the separated chromatids are regarded as chromosomes and are pulled to opposite poles of the spindle.

Question 29

What occurs in telophase 2?

Answer 29

The chromosomes uncoil and decondense as the nuclear envelope reforms around each chromosome set. Telophase is then followed by the division of the cytoplasm.

Question 30

What is the difference between cytoplasm division in female and male meiotic cells?

Answer 30

females- most of the cytoplasm is regained in one product called an oocyte which will develop into an egg and the other 3 cells are disregarded as polar bodies.
males- the cytoplasm divides evenly in both meiotic divisions resulting in sperm

Question 31

Sexual reproduction involves what 2 processes?

Answer 31

fertilization and meiotic cell division.

Question 32

What is the polity of a zygote?

Answer 32

diploid having 2 separate sets of chromosomes, one from each parent.