The Cell Cycle

Order of cell organization……… Cell  Tissue  Organ  Organ System  Organism **Cells must divide and create many cells in order for this process to occur

The Cell Cycle  Interphase, Mitosis and Cytokinesis Interphase (G1, S and G2) G1 – (Organelles Duplicate) S – DNA synthesizes (also called duplicates or replicates) G2 – (Cell prepares to divide)

The Cell Cycle **Interphase  Organelles replicate, DNA synthesizes and cell prepares to divide ** Mitosis is Asexual Reproduction Divides Nucleus **Cytokinesis  Divides Cytoplasm

Interphase – Prepares for Mitosis ** Majority of time for a cell is in this phase ** Cell grows ** Organelles duplicated (G1) **DNA synthesizes (S) ** Only chromatin (uncoiled chromosomes) visible

Chromosomes Duplicate In the S Phase of Interphase Carriers of genes Some genes carry the “instructions” for protein production Remember, chromosomes are duplicated during the S phase of Interphase prior to mitosis! You have 46 total chromosomes in the nucleus of most of your cells!!

**Nuclear Division Called Mitosis

**Prophase **Metaphase After Interphase **Anaphase **Telophase **Four phases of mitosis (cell division) are: **Prophase **Metaphase **Anaphase **Telophase **Recall Mitosis Divides the nucleus, Cytokinesis Divides the Cytoplasm

Prophase ** Duplicated chromosomes become visible ** A spindle, football shape structure that contains many fibers, moves to opposite poles

Metaphase **Chromosomes line up in the MIDDLE of the cell ) its equator) **Each chromatid is attached to a separate spindle fiber by its centromere (in the middle!!)

Anaphase ** Centromeres split pulling apart sister chromatids. ** Chromatids move to opposite poles

Telophase ** Chromosomes uncoil back into chromatin Animal Cell ** Chromosomes uncoil back into chromatin ** Two nuclei appear ** In animals a cleavage furrow forms (plants have a cell plate) ** In plants a cell plate forms between the 2 cells

Cytokinesis – Division of Cytoplasm ** Two new identical daughter cells after

Mitosis at a Glance– Cell Division

Cytokinesis in an Animal Cell ONLY in animal cells

Cytokinesis in a Plant Cell Only in Plants Only in Plants

Onion Root Tip – Can You Find the Stages of Mitosis

Mitosis in Real Time

Modeling Mitosis

Really Cool Animation

Cell Cycle in Prokaryotes (Bacteria) **NO TRUE NUCLEUS!!! DNA replicates and the plasma membrane just pinches inward to form two new cells.