Mitosis and Cytokinesis Chapter 6.3

The Cell Cycle The Cell Cycle is a repeating sequence of cellular growth & division during the life of an organism.

Pre Mitosis- Interphase Phase of cell division when the cell copies its DNA grows larger & prepares to divide. A cell spends 90% of its lifetime in Interphase There are 3 sections of Interphase: G 1, S, and G 2

Interphase- G 1 Phase “G 1 ” Phase= First Growth phase 90% of the cells life is spent in the G 1 phase\ Carries out routine functions, grows Some muscle and nerve cells never leave this stage… what does this mean?

Interphase- “S” phase “S” phase = Synthesis Phase DNA is copied

Interphase- G2 Phase “G 2 ” Phase= 2 nd Growth Phase Microtubules form to prepare for division Microtubules- Hollow protein fibers that help pull chromosomes apart

Mitosis! Mitosis- Process of cell division where the nucleus divides Occurs in 4 Steps  Prophase  Metaphase  Anaphase  Telophase

Mitosis Stage 1- Prophase Nucleus Breaks Down Spindle Forms to pull microtubules Chromosomes are visible

Mitosis Stage 2- Metaphase Chromosomes line up at the equator

Mitosis Stage 3- Anaphase Chromosomes split Chromosomes are pulled to opposite sides of the cell

Mitosis Stage 4- Telophase The Nucleus reappears The cell begins to split

Post Mitosis- Cytokinesis The cell splits into two cells by:  Cleavage Furrow- occurs in animal cells/ cells without cell walls  Cell Plate Formation- occurs in plant cells/ cells with cell walls

IMPORTANT !!!!!!!!! Interphase and Cytokinesis are NOT considered Mitosis! MITOSIS is ONLY…  PROPHASE  METAPHASE  ANAPHASE  TELOPHASE