1. Asexual Reproduction & Mitosis

2. Asexual Reproduction
Definition: one parent produces genetically identical offspring
Advantages:
Can produce offspring w/o a mate
Many offspring in short time
Disadvantages:
No variation in offspring
No adaptation to new/changing environments

3. Asexual Reproduction What kinds/types of reproduction are asexual?
Budding - a new individual grows on a ‘parent’
Example: hydra, yeast

4. Asexual Reproduction What kinds of reproduction are asexual?
2. Binary Fission - a ‘parent individual’ splits into two independent organisms
Example: bacteria

5. Asexual Reproduction What kinds of reproduction are asexual?
3. Regeneration - fragments of the ‘parent’ can grow into new
organisms
Example: starfish, planarian

6. Asexual Reproduction What kinds of reproduction are asexual?
4. Parthenogenesis - production of offspring from
unfertilized eggs

7. Asexual Reproduction What kinds of reproduction are asexual?
5. Vegetative reproduction - occurs in plants
New plants rise w/o the production of seeds or spores

8. Mitosis Makes two cells that are genetically identical to each other
Purpose? – growth and repair

9. Chromosomes -Passed on from one generation to the next
-Genetic material composed of genes which are made up of DNA
Only visible during cell division
Found in the nucleus
Condensed DNA

10. How DNA forms chromosomes

11. Chromatin Chromatin – uncondensed DNA; appears very “stringy”
Form of DNA between cell divisions

12. Parts of a Chromosome
Sister chromatids: identical copies of a chromosome
Made during the S phase of the cell cycle
Centromere: holds two
sister chromatids
together

13. The Cell Cycle

14. The Cell Cycle Interphase: Mitotic Phase: G1 phase: cell growth
S phase: DNA is replicated/copied
G2 phase: more cell growth
Mitotic Phase:
Mitosis/Cell Division
Cytokinesis (division of cytoplasm)

15. Mitosis
Prophase
Anaphase
Metaphase
Telophase

16. Prophase of Mitosis Chromatin coils up into visible chromosomes
Centrioles migrate to opposite ends
Nuclear envelope and nucleolus break down
Centromere of chromosome starts to attach to spindle fibers

17. Metaphase of Mitosis
Chromosomes line up in the middle of the cell

18. Anaphase of Mitosis Spindle fibers contract (shorten)
Chromosomes are pulled apart
Sister chromatids move to opposite poles

19. Telophase of Mitosis Chromosomes gather at opposite poles
Nuclear envelope starts to reform

20. Cytokinesis Division of the cytoplasm
Plant Cells: cell plate is formed → cell wall
Animal Cells: cleavage furrow formed

21. Summary of Mitosis
Start with 1 parent cell and ends with 2 daughter cells
2 daughter cells are formed that are genetically identical to the parent cell
Occurs in somatic cells (aka, body cells)
Functions in growth and repair of cells

22. Virtual Animation of Mitosis
Check out this site:
Virtual Mitosis Animation

23. Cell Cycle Regulation
Cyclin – a group of proteins that regulates the timing of the cell cycle
Controls when cells go from G1 to S phase
Controls when cells go from S to G2 phase
Controls when cells go from G2 to M phase

24. Uncontrolled Cell Growth
Cancer – abnormally rapid cell division
Cells of the tumor may break lose and spread or metastasize through the body
May be caused by radiation, pollution, bad luck, viral exposure
Many cancer cells have a mutation/defect in gene p53 (gene that normally tells the cell to wait until all chromosomes have been replicated before proceeding to mitosis)