5.2 Mitosis

Some Terms You Need to Understand

• Chromosome– long strand of DNA• Chromosomes condense at the beginning of

Mitosis• DNA will wrap around histones, which condenses

it.

Chromosome Structure

DNA doublehelix

DNA andhistones

Chromatin SupercoiledDNA

A Few More Terms

• Chromatin—When DNA wraps around histones, what is formed is called a chromatin.

• Chromatid– 1 half of a duplicated chromosome.

• Centromere• telomere

Condensed, duplicated chromosome

The Beautiful Process Called The Cell Cycle

• Interphase prepares the cell to divide– Time for duplication of organelles and DNA

replication– 2 full sets of DNA that are large enough to divide– G1, Synthesis, G2– G1—after cell division, matures and grows, makes

cytoplasm and organelles, carries out normal functions

– S—DNA replication– G2—makes all structures needed to survive

Cell Division in Prokaryotes

• Prokaryotes have no nucleus• Divide asexually by binary fission• Chromosome (circular) copies itself and

becomes 2x the original size• Cell wall forms between chromosomes and

parent cell splits in two• Results in 2 identical daughter cells

Cell Division in Eukaryotes

• MITOSIS!!!!!!!!!!!!!!!!!!!!!!!

Mitosis

• PMAT• Prophase—chromatin

condenses to chromosome.– Nuclear envelop breaks

down, nucleolus disappears, centromeres and centrioles start to migrate to opposite sides

– Spindle fibers grow from centrioles and radiate to center of cell.

PMAT

• Metaphase– spindel fibers attach to protein structure on centromere– Align chromosome along the equator of cell

PMAT• Anaphase—sister chromatids separate – Spindle fibers begin to shorten– This pulls sister chromatids away from each other– They move to opposite sides of the cell

PMAT

• Telophase—complete set of identical chromosomes are at each pole of the cell– Nuclear membrane

starts to form– Chromosomes start to

uncoil– Spindle fibers fall apart

The Final Part• CYTOKINESIS—divides

cytoplasm into 2 cells and goes through the cycle again.

Mitosis at a Glance

Find the Stage