1. Cell Division and Regulation of the Cell Cycle

2. Chromosomes
Made of DNA (which carries coded genetic information) and proteins
Each organism has a certain number
Humans have 46
Not visible until division because it is spread throughout the nucleus
During division, they condense
Prior to condensing, they replicate, so they consist of sister chromatids with centromeres near the center

3. Cell Cycle
A series of events during which the cell grows, prepares for division, and divides to form two daughter cells
G1, S, G2, M phases
Interphase – cell growth, synthesis of organelles and proteins, DNA replication
Mitosis – the division of the cell nucleus

4. Mitosis
Prophase – chromosomes condense and centrioles separate, spindle forms, nuclear envelope breaks down
Metaphase – chromosomes line up across the center of the cell
Anaphase – sister chromatids separate
Telophase – chromosomes unravel, nuclear envelope reforms around new nuclei of daughter cells

5. Cytokinesis The division of the cytoplasm
In animals – cells pinch apart into nearly equal halves
In plants – a cell plate (then a cell wall) forms

6. Controls and Regulators
Cells that come in contact with other cells stop dividing
Cyclins are proteins that regulate the cell cycle
Two kinds of regulators
Internal – proteins that respond to events in the cell
External – proteins that respond to events outside the cell

7. Uncontrolled Cell Growth
Cancer – a disorder in which some of the body’s own cells lose the ability to control growth
Do not respond to regulators
Form tumors that can damage surrounding tissues
Control over cell cycle has been broken down