Meiosis

Question 1

What happens in Meiosis I?

Answer 1

each chromosome will pair with the homologous chromosome forming a paired structure called a tetrad.. Homologues then separate

Question 2

What happens in Meiosis II?

Answer 2

Dyads separate into monads in Meiosis II. The outcome is that each cell receives half the chromosomes of the parental cell. When these cells fuse in fertilization, the full diploid complement is recovered.

Question 3

What is reductional and equational division?

Answer 3

the number of centromeres- halved in the Meiosis I –hence reductional- but kept equal in Meiosis II- hence equational.

Question 4

What are the 5 phases of prophase in meiosis I?

Answer 4

Leptonema
Zygonema
Pachynema
Diplonema
Diakinesis

Question 5

What happens in leptonema?

Answer 5

chromosomes condense into chromomeres and a process of homologous search takes place

Question 6

What happens in zygonema?

Answer 6

chromosomes are paired with their homologue, about 300nm apart, and the synaptonemal complex begins to form. This complex brings the chromosomes much closer

Question 7

what happens in pachynema?

Answer 7

chromosomes are only at 100nm and synapsis occurs between homologous chromosomes. During this phase cross-over takes place, there is exchange of genetic material between non-sister chromatids.

Question 8

What happens during diplonema?

Answer 8

the homologues begin to separate but they remain intertwined at certain areas called chiasma (or chiasmata in plural). These represent points where chromatids have exchanged material during the process of crossing over.

Question 9

What happens during diakinesis?

Answer 9

the nuclear membrane dissolves, the spindle fibres form and the centromeres attach to the spindle fibres.

Question 10

What happens in metaphase I?

Answer 10

terminal chiasmata are the only thing holding together the non-sister chromatids

Question 11

What happens in anaphase I?

Answer 11

the chromosomes move towards opposite poles, but here the pairs of homologous chromosomes separate and migrate to the opposite poles

Question 12

Daughter cells are formed as a result of meiosis are not similar to that of parent cell because…

Answer 12

Crossing over takes place and chromosome number is halved.

Question 13

In how many cells the meiotic division has taken place if the total number of spermatids produced are 32?

Answer 13

8 cells. If each diploid progenitor cell produces 4 gametes, then 32/4=8