Reproductive Cell Division

Question 1

what is Meiosis?

Answer 1

another type of cell division by which a diploid germ cell duplicates its DNA and divides twice to produce four genetically different haploid gametes.

Question 2

What is a germ cell?

Answer 2

a special reproductive cells in the gonads (testes and ovaries) that produce eggs or sperm.

Question 3

What is a Haploid (N) cell?

Answer 3

contains only one complete set of chromosomes.

Question 4

How many nuclear divisions Meiosis require to separate and distribute the DNA into gamtes?

Answer 4

2

Question 5

What is the first nuclear division?

Answer 5

reduction division because the number of chromosomes gets reduced from diploid (2N) to haploid (N).

Question 6

What is the second nuclear division?

Answer 6

Equatorial division: chromatids that comprise a chromosome gets separated and distributed to different gametes.

Question 7

What are the stages of Meiosis 1?

Answer 7

Prophase 1; Metaphase 1; Anaphase 1; and Telophase 1.

Question 8

what happens during Prophase 1?

Answer 8

DNA condenses into visible chromosomes. 1. Homologous chromosomes pair up to form a tetrad (four). 2. maternal and paternal chromatids cross-over within a tetrad exchange pieces of DNA during Prophase 1. 3. nuclear envelope disintegrates. 4. Nucleoli disappear. 5. centrioles assemble microtubules into a spindle apparatus.

Question 9

What happens during Metaphase 1?

Answer 9

tetrads line-up at the center of the cell. 1. pair of chromatids that make up each homologous chromosome lie on opposite sides of the cell’s equator. No centremeres on equator.

Question 10

What happens during Anaphase 1?

Answer 10

tetrads separate and the two chromatids that make up each homologous chromosomes more toward opposite poles of the cell.

Question 11

What happens during Telophase 1?

Answer 11

Cytoplasm gets divided and two haploids cells result. 1. unpaired chromosomes de-condense into a tangled mass of chromatin. 2. a new nuclear envelope forms around each tangled mass of chromatin. 3. spindle apparatus is disassembled. 4. nucleoli reppear. You have completed reduction.

Question 12

When does interkinesis happen?

Answer 12

during Meiosis 2

Question 13

What is interkinesis?

Answer 13

It is the beginning of Meiosis 2, and is the resting phase. The quiet phase when each haploid daughter cell prepares to divide again.

Question 14

What happens during the second nuclear division of Meiosis 2?

Answer 14

it is similar to mitosis because pairs of non-identical chromotids are separated and distributed into 4 gametes.

Question 15

What is the major difference of second nuclear division between Mitosis and Meiosis 2?

Answer 15

Meiosis 2 involves haploid cells while Mitosis involves diploid cells.

Question 16

what is the purpose of Meiosis?

Answer 16

Reduces the chromosomes number from diploid to haploid and distributes genetically different chromatids from each tetrad inot 4 different gametes.

Question 17

When does the duplication of Human DNA happen and how many chromosomes and chromatids are there?

Answer 17

It happens during Interphase and produces 46 chromosomes, each consisting of 2 chromatids for a total of 92 chromatids.

Question 18

How many tetrads are the chromatids organized into?

Answer 18

23 tetrads.

Question 19

what happens during the First Meiotic division?

Answer 19

reduces the number of chromosomes from 46 in the diploid germ cell to 23 in each haploid daughter cell.

Question 20

Are the chromatids identical in the 23 chromosomes?

Answer 20

No they are not identical because of cross over.

Question 21

What happens during the second meiotic division?

Answer 21

separates each of the 23 pairs of chromatids in each daughter cell and distributes them into a pair of gametes.

Question 22

how many gametes are produced and how many chromosomes does each gamete contain?

Answer 22

four gametes are produced and each gamete contain 23 chromosomes.