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CHAPTER 10 CELL DIVISION Mitosis - One cell dividing into 2 identical cells (somatic cells) healing and growth Meiosis - production of sex cells (gametes)

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Presentation on theme: "CHAPTER 10 CELL DIVISION Mitosis - One cell dividing into 2 identical cells (somatic cells) healing and growth Meiosis - production of sex cells (gametes)"— Presentation transcript:

1 CHAPTER 10 CELL DIVISION Mitosis - One cell dividing into 2 identical cells (somatic cells) healing and growth Meiosis - production of sex cells (gametes)

2 THE CELL CYCLE A “DAY” IN THE LIFE OF A CELL
Interphase G1 - Period of growth for the new cell S (synthesis) - Copying of DNA (replication) G2 - Preparation for division, organelles needed for cell division are produced M - Cell Division Division of the nucleus - Mitosis Division of the cytoplasm - Cytokinesis

3 Cell Geography Chromosomes are pulled towards the poles
Equator Pole Pole Chromosomes line-up on the equator during cell division Chromosomes are pulled towards the poles

4 Structures Necessary for Cell Division
Centrioles - organelles that help to separate chromosomes in animal cells only Spindle - formed by and between the centrioles, made from microtubules, attaches to each chromosome

5 Replicated Chromosomes
1. Made up of DNA and proteins 2. Only visible prior to cell division during rest the DNA takes the form of chromatin 3. Replicated chromosomes are made up of 2 sister chromatids held together by a centromere (separate but joined) 4. Sister chromatids are identical (duplicated chromosome) Text Replicated Chromosomes Human somatic cells have 46 chromosomes Sister chromatids Spindle

6 Interphase Period of growth for the cell Includes G1, S, G2
Plant cell Animal Cell Period of growth for the cell Includes G1, S, G2 Chromosomes are not visible (chromatin)

7 Mitosis PMAT Division of the nucleus occurs in 4 phases:
Prophase - Pro- (beginning) Metaphase - Meta- (between) PMAT Anaphase - Ana- (up from) Telophase - Tel- (end)

8 Prophase DNA (chromatin) condenses (thickens) into chromosomes
Nuclear membrane breaks down so the nucleus can divide Centrioles begin to separate creating a spindle in between them

9 Metaphase Chromosomes line up on the equator
Centrioles have migrated to the poles Each chromosome is attached to a spindle fiber at the centromere

10 Anaphase The spindle separates the chromosomes pulling
the chromatids towards the poles

11 Telophase Chromosomes gather at the poles and cytokinesis begins
Cytokinesis is division of the cytoplasm

12 Division of the cytoplasm
Cytokinesis Division of the cytoplasm Plant Cell Animal Cell

13 Prophase? Metaphase? Anaphase? Telophase?

14 Eukaryotes Prokaryotes Egg or Sperm 2 identical cells
Gamete Production Egg or Sperm 2 identical cells

15 How do cells know when to divide?
White blood cell Red Blood Cells Some cells never divide Why not? They do not have a nucleus

16 Different Cell Cycle Rates for Different Cells
Digestive lining cells move through the cycle quickly Cardiac muscle cells do not divide

17 Why don’t cells just continue dividing?
Contact inhibition - cell division stops when a cell comes into contact with another cell No contact inhibition - cells growing on top of one another Contact inhibition - cells are spread apart

18 Cyclins - proteins that regulate the timing
Cell Cycle Regulators Cyclins - proteins that regulate the timing of the cell cycle Internal regulators - proteins that respond to events inside the cell, e.g. check to see that all of the chromosomes have replicated correctly External regulators - proteins that respond to events outside of the cell, hormones

19 Cancer Occurs when a cell loses the ability to regulate its cell cycle
Overgrowth of cells - no contact inhibition Benign tumor - does not spread beyond the original site Metastasis - cancer cells that have moved to other parts of the body

20 Cancer Cells Breast Cancer Cell Brain Cancer Cell Prostate Cancer Cell


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