Review What is the cell cycle? What are the two stages of the cell cycle? Why do cells need to...

Mitosis

ReviewWhat is the cell cycle?What are the two stages of the cell cycle?

Why do cells need to divide?

ChromosomesIn cells DNA is tightly wound up into chromosomes

Chromosomes are not visible, but become visible in mitosis

Humans have 23 pairs of chromosomes

Chromosome before DNA replication

Chromosome after DNA replication

Chromatid – One half of a duplicated chromosome

Centromere – Middle of a chromosome

Midlesson ReviewWhat is a chromosome?How many pairs of chromosomes do humans have?

What is a centromere?

Mitosis4 stages

ProphaseMetaphaseAnaphaseTelophase

Prophase1st stageNuclear envelope breaks down

Chromosomes become visible

Spindle forms

MetaphaseChromosomes line up in middle

Spindle attaches to each centromere

AnaphaseEach sister chromatid is pulled apart

TelophaseThe two sets of chromosomes are now at separate ends of the cell

Two nuclear envelopes form around the chromosomes

Cytokinesis –Not Mitosis--After mitosis the cell splits in two

Animals – cell pinches down the middle

Plants – Cell plate forms down the middle

ReviewWhat are the 4 phases of mitosis?What happens in first stage of

mitosis?What happens in the second stage of

mitosis?What happens in the third stage of

mitosis?What happens in the fourth stage of

mitosis?What happens in cytokinesis?