Cellular Division-cells split to make more cells

Why do cells divide?

Asexual

GrowthRepair

Sexual

To stay small for metabolism

Reproduction

Main Stages of Cell Life Cycle1-Interphase

Protein SynthesisReplication

2-MitosisCell Division

Mitosis Steps1. Chromosomes coil

up2. Move to the middle3. Sister chromatids

pulled apart4. Cells split into 2

identical body cells5. Chromosomes uncoil

to resume protein synthesis

1

2

3

4

5

Chromosome # by Species1/2 from mom1/2 from dad

Diploid (2N)= full set of chromosomes

Total # is even

How do you get 1/2 from each parent?Meiosis!=

cell division resulting in 4 haploid (1N) gamete cells (egg/sperm)

Sexual Repro by Meiosis increases genetic diversity

= Diploid Zygote (2n)

Haploid egg (1n) + Haploid sperm (1n)

Mitosis vs Meiosis • Two divisions• Homologous

chromosomes line up • Cross over• Homologous pairs split• Second division sister

chromatids split• 4 different (1N)

gametes (egg or sperm)

I

II

Homologous Chromosome alignment creates gamete variety (Indep. Assortment)

Parent

GgYy

Mitosis Meiosis

Diploid (2n)Haploid (1n)

Homologous chromosomes

line up & split

Sister Chromatids

line up & split

Crossing Over -chromosomes swap sections

Crossing over!