Mitosis and the Cell Cycle Chapter 10 Mitosis and the Cell Cycle

Mitosis Song

Fun Facts DNA from one cell stretched out would be 2 m long DNA from a baby would have 15 round trips from the sun to Pluto

Chromosomes Def. – DNA that is organized and packaged into structures DNA is composed of hereditary units called genes

Chromosomes (cont.)(page 225) Organized by super-coiling They are coiled around a protein called a histone. A DNA wrapped histone is then called a nucleosome.

Cell Cycle Cell cycle= the cell’s life cycle Made up of 3 parts Interphase Mitosis Cytokinesis

Cell cycle continued Interphase This is where the cell will spend most of its life During this phase the cell is not dividing 3 phases G1 (First gap phase) S (Synthesis phase) G2 (Second gap phase)

Interphase G1 Grows rapidly S Cell’s DNA is copied G2 Continues to grow and prepares to divide

Cell cycle continued Cell Division- the following two steps is where the cell divides Mitosis Nucleus divides Cytokinesis Division of cytoplasm

Mitosis- 4 phases (pg 231) Prophase Chromosomes become thick and visible Nuclear membrane breaks down Centrioles move to the poles Spindle fibers form (attached to centrioles)

Mitosis Metaphase Nuclear membrane is completely gone Chromosomes MEET in the middle of the cell Spindle fibers attached to centromeres

Mitosis Anaphase Spindle fibers shorten Sister chromatids (half an X) start to move to opposite sides of the cell (now a chromosome) Ends when the chromosomes reach the poles

Mitosis Telophase A nuclear membrane forms around the chromosomes at each pole Chromosomes uncoil and change back into chromatin form (spaghetti) Spindle fibers break down and disappear

Cytokinesis- last part Splitting of the cytoplasm Different in plants and animals Plants pg. 232 Have a cell plate form in the middle of the cell

Cytokinesis (cont.) Animals Cell is pinched in half by a belt of protein threads Balloon and string demo