1. Unit 8: Cell Cycle & Mitosis
How do baby elephants grow up to be BIG elephants?
Why do animals shed their skin?

2. CELL REPRODUCTION
Cells make more cells by growing and dividing millions of times a day!!
Two types of cell reproduction:
Asexual
Sexual
Two types of cell division:
Mitosis
Meiosis

3. ASEXUAL VS. SEXUAL REPRODUCTION
One parent
Offspring are clones!!
Sexual:
Two parents
Offspring resemble both parents!

4. 3 REASONS WHY CELLS REPRODUCE BY ASEXUAL REPRODUCTION (MITOSIS) GROWTH
REPAIR
REPLACEMENT
Cells that reproduce by mitosis reproduce constantly and are called somatic cells!!
Body Cells

5. Before a cell can divide it needs instructions!!!
GENETIC MATERIAL - DNA
Before a cell can divide it needs instructions!!!

6. CHROMOSOMES In Humans… Somatic Cells: 46 chromosomes (diploid)
Reproductive Cells:
23 chromosomes (haploid)

7. Cell Division/Cell Cycle
CELL DIVISION OCCURS IN A SERIES OF STAGES, OR PHASES:
Interphase
Prophase
Metaphase
Anaphase
Telophase & Cytokinesis
Mitosis

8. INTERPHASE
Cell grows!!!
Copies genetic material (DNA) and other cell organelles

9. Gap 1 (G1) 1st Growth Stage Cells make cytoplasm and organelles
Cells perform normal duties
Cells grow RAPIDLY
Most remain here most of their life.

10. Synthesis (S) DNA is copied or replicated.
At the end: each chromosome consists of 2 chromatids attached at the centromere.

11. Gap 2 (G2) 2nd Growth Stage Cell division structures are made
Centrioles – move chromosomes during mitosis
Organelles & proteins are synthesized
PREP for nucleus to divide

12. PROPHASE Genetic material condenses (shrinks!) to form chromosomes
Mitosis Begins!!
Genetic material condenses (shrinks!) to form chromosomes
Nuclear membrane dissolves
Centrioles move to opposite poles
Spindle fibers form

13. METAPHASE Chromosomes line up in the middle of cell
Meta = Middle!
Chromosomes line up in the middle of cell
Spindle fibers are attached!!

14. ANAPHASE
Chromosomes are pulled apart and chromatids move to opposite ends of the cell by the spindle fibers.

15. TELOPHASE Chromatids relax Nuclear membranes form around chromatids
Spindle fibers fall apart

16. CYTOKINESIS “Division of Cytoplasm”
Cleavage Furrow forms in animal cells – pinching inwards by tiny filaments.
Cell Plate forms in plants cells – forms in-between the two nuclei

17. RESULTS!!! Two daughter cells that are identical to the original cell.
Video Clip