MITOSIS the key to growth

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

Mitosis is part of the Cell Cycle The cell cycle is divided into 5 phases. 1. Interphase 2. Prophase 3. Metaphase Mitosis 4. Anaphase 5. Telophase **This is a moving, continuous process. Stages are for study.

Period of growth and normal cell activity Interphase Period of growth and normal cell activity Events 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

Interphase Look for a distinct nucleus

Mitosis: Prophase Three things happen: Chromatin coils and become visible chromosomes. The nuclear membrane breaks down and disappears The spindle fibers & centrioles forms

Mitosis: Prophase Look for chromosomes in the center

Mitosis: Metaphase Chromosomes line up on the “equator” (in the middle of the cell) Chromatids attach to the spindle fibers at the centromere

Mitosis: Metaphase Look 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: Anaphase Look for chromosomes in two groups pulling apart

Mitosis: Telophase The 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: Telophase Look for two groups of chromosomes with a cell plate or cleavage furrow

Cytokinesis The 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

Animals Plants Differences in plant and animal cells: centrioles summary Animals Plants centrioles no centrioles cleavage furrow cell plate cell wall