MITOSIS

the key to growth

Mitosis - the division of the nucleus into two equal sets of genetic informationBasically, simple cell division

Mitosis is part of the Cell Cycle

The cell cycle is divided into 5 phases.1. Interphase

2. Prophase

3. Metaphase

4. Anaphase

5. Telophase

**This is a moving, continuous process. Stages are for study.

The Cell Cycle

Interphase

Mitosis

Cytokinesis

Mitosis

Interphase Period of growth and normal

cell activityEvents of Interphase:•90% of the cell life.•DNA is in the form of chromatin.•DNA replicates, making two exact copies of each chromosome.•2 centrioles appear.

Stages of interphase:• G1 (Gap 1) – normal cell growth•S (Synthesis) – DNA synthesis (replication)•G2 (Gap 2) – prepares for cell division

Look for a distinct nucleus

Interphase

Mitosis: Prophase

Three things happen:

Chromatin coils and become visible chromosomes.

The nuclear membrane breaks down and disappears

The spindle fibers & centrioles forms

Mitosis: ProphaseLook for chromosomes in the center

Mitosis: MetaphaseChromosomes line up on the “equator” (in the middle of the cell)

Chromatids attach to the spindle fibers at the centromere

Mitosis: MetaphaseLook for chromosomes lined up on the “equator”

Mitosis: Anaphase

Chromosomes pull apart in opposite directions towards the “poles”

This phase ends when the chromosomes reach the poles.

Mitosis: AnaphaseLook for chromosomes in two groups pulling apart

Mitosis: TelophaseThe fourth and final phase of mitosis

The opposite of Prophase

Chromosomes unwind to form chromatin

Two new nuclei form with new membranes

The spindle disappears

Mitosis: TelophaseLook for two groups of chromosomes with a cell plate or cleavage furrow

CytokinesisThe division of the cytoplasm

Animal cells pinch inward forming a cleavage furrow.

Plant cells divide from the inside towards the outside by forming a cell plate which becomes the cell wall.

Cytokinesis

Animals:Cleavage furrow

Cell plate cell wall

Differences in plant and animal cells:summary

Animals Plants

centrioles no centrioles

cleavage furrow cell plate

cell wall