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

Recall that genes are on chromosomes  you have 46 total (44 plus 2 sex chromosomes; XX or XY) Your cells, other than sex cells, contain a diploid set of chromosomes This means you have a pair of each chromosome in your cells, one from each parent ~Red chromosomes are from your mom, blue from your dad ~Notice they do not look like X’s…..They look that way AFTER they replicate!!

The Cell Cycle  Interphase, Mitosis and Cytokinesis G 1 – (Organelles Duplicate) G 2 – (Cell prepares to divide) S – DNA synthesizes (also called duplicates or replicates) Interphase (G 1, S and G 2 )

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

Carriers of genes that code for proteins “instructions” for protein production or genes that regulate other genes Sister chromatids held together by the centromere (Usually see this in the center!)

Sister Chromatids Centromere

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

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

**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!!)

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

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

** Two new identical daughter cells after

ONLY in animal cells

Only in Plants

**NO TRUE NUCLEUS!!! DNA replicates and the plasma membrane just pinches inward to form two new cells.

CANCER Called Malignant Due To Uncontrolled Cell Division Forms Masses of Tissue called tumors May Result From Genetic Changes Deprives Normal Cells of Nutrients One or More Genes

** Damaged or mutated Genes ** from ultraviolet light, smoking, pollution etc. ** Some viruses can, but bacteria is not known to ** Both genetics and the environment play a role in cancer.