Modeling Meiosis (Page 2 of 4) in pdf

Modeling Meiosis Page 2

Anaphase I - Significant Events: Homologues Separate, Chromosome Number is Reduced

During anaphase, the homologous chromosomes separate and are

pulled to opposite sides of the cell. This represents a second

significant difference between the events of mitosis and meiosis

as the chromosome number is reduced from diploid to haploid.

Note that each chromosome is still composed of two chromatids

joined at the centromere.

Telophase I - Significant Event: 2 Haploid Groups of Chromosomes Are Formed

Place each chromosome at opposite sides of

the cell. Centriole duplication takes place at

the end of telophase in preparation for the

next division. Formation of a nuclear envelope

and division of the cytoplasm (cytokinesis)

usually occurs at this time to produce two

cells. Notice that each chromosome still

consists of two chromatids.

Meiosis II

A second meiotic division is necessary to separate the chromatids of the chromosomes in the two daughter

cells formed by this first division. This will reduce the amount of DNA to one double-helical strand per

chromosome. This second division is called meiosis II. It resembles mitosis except that only one homologue

from each homologous pair of chromosomes is present in each daughter cell undergoing meiosis II.

Interphase II (Interkinesis) – Significant Event: DNA Replication DOES NOT Occur

The amount of time spent “at rest” following telophase I depends on the type of organism, the formation of

new nuclear envelopes, and the degree of chromosomal uncoiling. Because interphase II does not necessarily

resemble interphase I, it is often given a different name—interkinesis. DNA replication does not occur during

interkinesis. This represents a third difference between mitosis and meiosis.

Prophase II – Significant Event: Replicated Centrioles Separate

Replicated centrioles separate and move to opposite sides of the chromosome groups.

Modified from AP Biology, Exercise 3B, Student Guide from Carolina Biological Supply

Modeling Meiosis Page 2