The Cell Cycle, Mitosis, and Cancer Glencoe Biology Chapter

What causes cancer? Cancer is caused by mutations which creates abnormal cell growth. A mutation is a change to an organism’s DNA.

What causes mutations? (changes our DNA?) Radiation UV radiation X rays Chemicals Alcohol Tobacco Drugs Infectious agents Viruses like HPV

Genetic Material During most of the cell’s life, genetic material exists in chromatin Chromatin = DNA that is long and tangled Chromatin coils up (during M phase) to form chromosomes When UNCOILED, chromatin makes proteins and can replicate itself When COILED, cell division can occur

Anatomy of a Chromosome

The Cell Cycle The growth period is called INTERPHASE The stage during which the cell carries out cellular functions Also the stage in which it grows and replicates its DNA. INTERPHASE S (DNA synthesis) G1 Mitosis G2 Cytokinesis MITOTIC (M) PHASE

The Cell Cycle The nuclear division period is called M PHASE (Mitosis) G1 G2 S (DNA synthesis) INTERPHASE Cytokinesis MITOTIC (M) PHASE Mitosis The nuclear division period is called M PHASE (Mitosis) the stage of the cell cycle during which the cell’s nucleus and genetic material divide. Consists of Prophase, Metaphase, Anaphase, and Telophase (PMAT)

The Cell Cycle The cytoplasmic division period is called CYTOKINESIS The method by which a cell’s cytoplasm divides, creating a new cell. INTERPHASE S (DNA synthesis) G1 Mitosis G2 Cytokinesis MITOTIC (M) PHASE

Why do cells need to divide? REPRODUCTION in UNICELLULAR organisms Development, Growth, and Repair in SOMATIC (body) cells

INTERPHASE – BEFORE MITOSIS centrioles chromatin Nuclear membrane

1st stage of Mitosis: Prophase During Prophase… Chromatin coils up into visible chromosomes The nucleus will disappear during this phase Centrioles will begin to separate centrioles chromosomes Nuclear membrane

2nd Stage of Mitosis: Metaphase During Metaphase… Spindle fibers pull the chromosomes to the middle (equator/metaphase plate) of the cell

3rd stage of Mitosis: Anaphase During Anaphase… Chromosomes will be pulled apart forming chromatids. Once the chromatids are separated, they will move towards opposite sides of the cell.

4th stage of Mitosis: Telophase During Telophase… The chromatids uncoil, becoming chromatin The nuclear envelope reforms Mitosis is COMPLETE!!!

Cytokinesis: last stage in the cell cycle The cytoplasm divides into two new cells. ANIMAL CELLS: The cell membrane will move inward and pinch apart PLANT CELLS: A new cell wall (cell plate) forms between the two new cells.

SUMMARY - MITOSIS Number of ROUNDS of cell divisions: 1 Number of daughter cells : 2 Genetically identical? Yes Chromosome #: Same as parent Where: Somatic cells (non-sex cells) When: Throughout life Role: Growth and repair

The complete CELL CYLCLE cell cycle video M-PHASE (mitosis + cytokinesis) MITOSIS

KARYOTYPE and Chromosome Number: Human chromosome number: 46 in body (somatic) cells (diploid OR 2N) 23 in sex cells (egg and sperm) (haploid OR N) A picture of species’ full set of chromosomes is a KARYOTYPE

S (DNA synthesis) INTERPHASE G1 G2 S (DNA synthesis) INTERPHASE Cytokinesis MITOTIC (M) PHASE Mitosis