1. BELLRINGER 11/03 What is Mitosis? 2. List the 4 Mitotic Phases?
Clue: Purple Monkeys Attack Tokyo
YOU NEED YOUR NOTEBOOKS!
Reminders: HW, Lab Fee, Grades and Midterm this Thursday!

2. CELL GROWTH & REPRODUCTION

3. Why do cells divide? Why can’t we just be one giant cell?
Small cells are more efficient
Cells must be small
Small cells have a greater Surface Area-to-Volume Ratio
When cells get too big, their surface area is not large enough for oxygen, food, and wastes to diffuse across
The cell would starve to death or be poisoned from waste

4. Cell Reproduction Vocab
Chromosomes = condensed DNA, they form when cell is ready to divide
Made up of 2 halves held together in the center by the centromere
Chromatin= a form of chromosomes that look like loose, unorganized spaghetti (this is what we see in Interphase)
Sister chromatids- exact copies of a chromosome held together by a centromere (this is what we see in the S phase when DNA is copied)

5. Cell Cycle Cell Cycle = sequence of growth & division of a cell
1. Interphase
2. Cell Division
Mitosis
Cytokinesis
Interphase = growth period, majority of a cell’s life
G1: Cells grow and makes proteins (enzymes)
S: Chromosomes containing DNA are copied
G2: Cell prepares for division

6. Mitosis
Mitosis = period of cell division, 2 daughter cells get formed in the end, each with its own nucleus with identical chromosomes
Divided into 4 Phases
PMAT

7. 1. Prophase
Chromatin thickens and coils into visible chromosomes (2 sister chromatids)
Nuclear Envelope & Nucleolus break down
Centrioles at opposite ends of cell start sending out Spindle Fibers between them

8. 2. Metaphase Chromosomes line up in the center of the cell
Spindle Fibers attach to the centromere of each of the sister chromatids and pulls them in the middle

9. 3. Anaphase
Separation of Sister Chromatids to the opposite ends (poles) of the cell
Centromeres split

10. 4. Telophase Chromatids pulled to opposite ends of the cell ends
Nuclear Envelope & Nucleolus re-form
Chromosomes appear as chromatin again
Mitosis ends
New daughter cells have identical DNA

11. Cytokinesis Cytokinesis = division of the cytoplasm
Cleavage (pinch) in animals
Cell Plate (new wall) in plants