Meisosis Stages

Question 1

What happens in Prophase I

Answer 1

Homologous chromosomes pair up to form bivalents and the nuclear membrane disperses. Each bivalent contains a total of 4 chromatids & has 2 centromeres. Spindle fibres emerge from the centrioles & kinetochores develop on the chromosomes.

Question 2

What happens in Metaphase I

Answer 2

The spindle-attached bivalents align along a metaphase plate.

Question 3

What happens in Anaphase I?

Answer 3

The chromosome dyads are pulled apart by spindle fibres to opposite pole ends of the cell. This aids in formation of haploid cells.

Question 4

What happens in Telophase I?

Answer 4

The nuclear membrane reforms and cytokinesis commences.

Question 5

What is the difference between Mitosis, Meiosis I & Meiosis II?

Answer 5

Mitosis is primary for growth & repair.
Meiosis I reduces chromosome number & increases genetic diversity.
Meiosis II separates sister chromatids without changing the chromosome number, e.g. 2 haploid daughter cells become 4 gamete cells.

Question 6

Chiasmata (crossing-over) is a process that takes place in Meiosis. What happens here and why is it important?

Answer 6

Crossing-over is a process by which segments of genetic material is exchanged between homologous chromosomes. This occurs when chromosomes are closely aligned, forming structures known as Chiasmata. This process is important for genetic diversity, producing new combinations of alleles, which leads to variations in traits among offspring.