How many stages of cell division do you see in this image? Genetics Unit: Mitosis How many stages of cell division do you see in this image?

Cell Cycle Mitosis will be our main focus. First, we will look at Interphase… )

Interphase Longest stage of cell division (90% of cell cycle) Nucleus is visible Cell is growing and DNA is being replicated. )

Most of these cells are in Interphase Interphase: 3 Phases G1: Cell is Growing S: DNA is Synthesized (DNA Replication) G2: Organelles duplicate in preparation for division )

Key Vocabulary DNA molecules are packaged into . chromosomes Human (body cells) have 46 Human (sperm or eggs) have 23 Chromosomes are made of a material called . chromosomes somatic cells chromosomes. gametes chromosomes. chromatin

Key Vocabulary Chromatin is composed of and . It is supercoiled around proteins, called . Together the DNA and histone molecules form bead-like structures called DNA proteins histones nucleosomes

Key Vocabulary The chromosome is duplicated. Each duplicated chromosome consists of two . These are connected by a . sister chromatids centromere

Mitosis (M Phase) Prophase Metaphase Anaphase Telophase The M Phase consists of: Mitosis and Cytokinesis Four Stages of Mitosis: Prophase Metaphase Anaphase Telophase For Homework: Left-side IntNB assignment: Write an Acrostic Poem for the four stages of Mitosis

Preparing for Division Late Interphase: G2 Centrosomes (with centriole pairs) Nuclear membrane still visible Nucleolus Chromatin has been replicated

Preparing for Division Late Interphase: G2 Prophase Centromere Early Spindle Apparatus Nuclear membrane disappears Chromosome consisting of two sister chromatids

The spindle attaches to the centromeres. Metaphase Chromosomes line up at an imaginary line between the centrosomes at opposite ends of the cell. The spindle attaches to the centromeres.

Spindles pull the “daughter” chromosomes appart Anaphase Spindles pull the “daughter” chromosomes appart

Telophase & Cytokinesis Two nuclei become visible In animal cells, a Cleavage Furrow is visible In plant cells, a cell plate is now visible Cytokinesis The cytoplasm and organelles divide.

What’s the end product? Two identical daughter cells ready to start the cycle again… or not. Some cells (like your nerve and muscle cells) do not undergo division. For those that do (your skin and the lining of your intestinal tract) how would you know how quickly division takes place?