Cell Cycle and Cell Division — Part 2: Meiosis: visual lesson, CBSE Class 11 Biology

Lesson

Meiosis

Part 2 — the reduction division that makes gametes and keeps the chromosome number constant.

In this lesson you will

Describe the substages of prophase I and the other stages of meiosis I and II
Count chromosomes, chromatids and DNA through meiosis
Compare mitosis and meiosis and explain the significance of meiosis

Concept

What happens in meiosis

Meiosis involves two sequential cycles of nuclear and cell division, meiosis I and meiosis II, but only a single cycle of DNA replication. It produces four haploid cells.

Table of the main features of meiosis
Feature	Meiosis
Starts from	A diploid meiocyte after S phase
DNA replication	Once, before meiosis I
Divisions	Two: meiosis I (reduction) and meiosis II (equational)
Ends with	Four haploid cells, a tetrad

Diagram

Prophase I: five substages

Prophase I is much longer and more complex than mitotic prophase. It is divided into leptotene, zygotene, pachytene, diplotene and diakinesis.

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