Ch 10 Mitosis
Cell Growth• Limits to Cell Growth
– Why do cells divide?•The larger a cell gets, the more
demands the cell puts on the DNA
Cell Growth
Before a cell gets too big, it divides forming two identical “daughter cells”
Cell Division• Every cell must copy its
DNA before cell division begins.
• Each daughter cell then gets a copy of that DNA
• In eukaryotes, cell division begins with the division of the nucleus called mitosis.
Chromosomes• Genetic information
is passed on by chromosomes
• Chromosomes are made of DNA
• Each chromosome is made of 2 sister chromatids and joined at the centromere.
Chromosomes
• When a cell is not in cell division, the DNA is found in the form of chromatin, not as chromosomes.
• DNA condenses to form chromosomes before cell division.
The Cell Cycle• During the cell cycle a
cell grows, prepares for division, and divides to form two daughter cells, each of which begins the cycle again.
• Interphase – Cell is preparing for division (G1, S, and G2 phase)
• AFTER Interphase, Mitosis begins. The daughter cells then enter Interphase. **CYCLE**
Cell Cycle Animation
Cell Cycle Animation p.2
Mitosis (PMAT)
• 1. Prophase• Chromosomes
condense and become visible
• Centrioles separate and get on opposite sides of the nucleus
•Centrioles help to organize the spindle fibers
**Mitosis occurs in Somatic Cells (body cells) when new cells are needed.**
Mitosis (PMAT)• 2. Metaphase
• Chromosomes line up across the center of the cell
Mitosis (PMAT)• 3. Anaphase
• The centromeres that holds the chromatids together split
• The spindle helps pull the pair of chromosomes apart
Mitosis (PMAT)• 4. Telophase
• Chromosomes gather at opposite ends of the cell
• Two new nuclear envelopes form
Mitosis
Uncontrolled Cell Growth• Cancerous
tumors are caused because cancer cells do not respond to the signals that regulate the growth of most cells.