The Case of the Dividing Cell

By Lauren and Robert

Life Cycle of a Cell - Mitosis

Interphase Prophase Metaphase Anaphase Telophase Cytokinesis

Interphase Longest stage 3 stages: G1, S, G2 G1 – cell accelerates biochemical processes that

were slowed down by mitosis S – DNA replication G2 – chromosomes condense

Prophase

Spindle fiber is formed Centrioles are duplicated Nuclear envelope begins to break up

Metaphase

Chromosomes line up in center of cell

Anaphase

Chromosomes split Move to opposite sides of the cell

Telophase

Chromosomes are completely separate Nuclear envelope begins to reform

Cytokenesis

Cells split apart Two daughter cells result

Cell Division – Prokaryotes vs. Eukaryotes

Prokaryotes use binary fission

DNA replicates; strands attach to membrane

Cell elongates; DNA separates

Cell wall and membrane grow from the center of cell causing division

Eukaryotes must go through all the steps of either mitosis or meiosis

Meiosis

1st half (Meiosis 1) is the same as mitosis 2nd round skips the DNA replication 4 haploid daughter cells result

Mitosis vs. Meiosis

Mitosis Asexual

reproduction 2 diploid cells result

Meiosis Sexual reproduction 4 haploid cells result

Crossing Over Exchange of genetic material between

homologous chromosomes Occurs during Prophase 1 of Meiosis However, similarities in sequences can

cause non-homologous chromosomes to cross over with each other.

Why is Meiosis Important for Sexual Reproduction?

Sexual reproduction uses two haploid cells They combine to produce a diploid offspring If the cells didn't divide a second time to

make a haploid, the offspring would have double the diploid