Cell Division – a review

Cell Cycle Control: What happens at each checkpoint?

M = mitosis (nuclear division)C = cytokinesis (cytoplasmic division)G = gap (cell growth)S = synthesis (DNA replicated, cell growth)

When to Divide?

Growth Inhibition

Control Problems - Cancer

Supercoiling (DNA coils forming a chromatid)

Human Chromosomes (unreplicated)

Human Chromosomes (replicated and supercoiled)

Chromosome (replicated)

Chromosome

Each DNA molecule coils to form a single chromatid. The two chromatids of a replicated chromosome are genetically identical.

The Cell Cycle (Overview)

Mitosis - Stages

Prophase and Metaphase

Anaphase and Telophase

Cytokinesis (animal and plant)

MEIOSISthe other type of nuclear division

Gametes…why haploid?

Oogenesis

Spermatogenesis

Meiosis

Meiosis Overview

Meiosis (Part I)

Meiosis (Part II)

Independent Assortment of Chromosomes

Independent Assortmentanother view

What happens when

chromosomes do not separate

properly during meiosis?

Nondisjunction

Down’s Syndrometrisomy 23

Crossing Over Leads to Genetic Variability

Compare Mitosis and Meiosis

Mitosis vs. Meiosis