Meiosis: Cell Division, Stages, and Genetic Variation

What is meiosis?

A type of cell division that produces gametes (sex cells) and reduces chromosome number by half.

What is another name for meiosis?

Reduction division.

What cells does meiosis produce?

Gametes (sperm and egg cells).

How many stages of division are in meiosis?

Two stages: Meiosis I and Meiosis II.

How many phases are in each stage of meiosis?

Four phases in Meiosis I and four phases in Meiosis II.

What is the main goal of Meiosis I?

To separate homologous chromosomes and reduce chromosome number to haploid.

What happens to DNA in prophase I?

It condenses into X-shaped chromosomes after replication.

What is synapsis?

The pairing of homologous chromosomes.

What is a tetrad?

A group of four chromatids formed by paired homologous chromosomes.

What are alleles?

Different versions of the same gene.

What is crossing over?

Exchange of genetic material between homologous chromosomes.

Why is crossing over important?

It increases genetic variation.

What disappears in prophase I?

Nuclear membrane.

What happens in metaphase I?

Homologous chromosomes line up at the cell equator.

What separates during anaphase I?

Homologous chromosomes.

What is the result of meiosis I?

Two haploid cells with sister chromatids still attached.

Are sister chromatids identical after crossing over?

No, they are no longer identical.

Does DNA replicate before Meiosis II?

No.

What is the goal of Meiosis II?

To separate sister chromatids.

What happens in prophase II?

Nuclear membrane disappears and spindle fibers form.

What happens in metaphase II?

Chromosomes line up at the equator.

What separates in anaphase II?

Sister chromatids.

What are sister chromatids called after separation?

Individual chromosomes.

What is the result of meiosis II?

Four genetically different haploid cells.

What is the final product of meiosis?

Four genetically different haploid gametes.

Why are gametes genetically different?

Crossing over and independent assortment.

Are gametes haploid or diploid?

Haploid.

What separates in Meiosis I vs Meiosis II?

Meiosis I: homologous chromosomes; Meiosis II: sister chromatids.