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 (G 1, S, and G 2 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.