1. Life Cycle
of a
Cell

2. Cell Size Why not just one large cell?
Difficult to get nutrients in and waste out

3. Phases of The Cell Cycle
G1,S, and G2 are known together as Interphase.

4. Sex cells are called gametes
Regular Cells
Somatic cell cycle 
Interphase – cell grows, copies its DNA and prepares for Mitosis by copying organelles
M phase- Cell division (Mitosis and cytokinesis)
Sex cells are called gametes

5. Interphase Chromosomes Condense
Chromosomes are inherited genetic information
Chromosomes are made up of DNA
Can only be seen when cells are dividing

6. Interphase Chromosomes replicate-or copy is made The two copies are
-attached together at a point called a centromere.
-are called sister chromatid.

8. Organelles must be replicated (copied)
Interphase
Organelles must be replicated (copied) 9

9. M Phase Two parts: Nuclear division Cytoplasmic Division Mitosis
Saturday, November 24, 2018
M Phase
Two parts:
Nuclear division
Mitosis
Cytoplasmic Division
Cytokinesis 10

10. Mitosis Nuclear Division.
Nucleus divides into two new nuclei Mitosis keeps the number of chromosomes constant from one cell generation to the next.
In eukaryotes, it is the main process by which growth and tissue repair is accomplished.
Mitosis is also the main process by which single-celled and many multi-celled eukaryotes reproduce asexually.

11. 4 Steps of Mitosis (PMAT)
 Prophase: Chromosomes condense and attach to the spindle fibers at their centromere.
Nuclear
Membrane
breaks down.

12. Steps of Mitosis (PMAT)
 Prophase: Centrioles move to opposite sides of the cell and organize the spindle fibers

13. Metaphase: Chromosomes attach to spindle fibers and line up in the middle of the cell

14. Anaphase: Chromosomes separate-Move to opposite sides of the cell

15. Telophase Nuclear Envelope reforms
There are now TWO nuclei in one cell!
Nuclear Envelope reforms
…And they contain the SAME genetic information*SAME NUMBER OF CHROMOSOMES

17. Cytokinesis Cytoplasmic division
Each cell gets half of the organelles.
After mitosis: cell pinches in half to form two new cells.

18. Cytokinesis Animal cells pinch.
Cytokinesis in plant cells is different from that in animal cells.

19. In plant cells a cell plate forms from the inside out.

21. Results of Mitosis and Cytokinesis
Two new cells.
The new cells- called daughter cells- have the same number of chromosomes as the mother cell.
This occurs in all somatic cells in your body.
You have 46 chromosomes in all of your somatic cells-23 pair!

22. Mitosis in Onion

23. Cells
during
Mitosis

24. Meiosis

25. Reproduction of Sex Cells
Sex cells- Sperm and egg
Process is called Meiosis
Similar to Mitosis

26. Meiosis Cell divides twice
First division is like mitosis and then the cell divides again to create 4 haploid cells.

27. MEIOSIS=CHROMOSOME REDUCTION DIVISION

29. Meiosis Meiosis is also know as chromosome reduction division.
Start with 46 and ends up with 23.
Why?
Fertilization creates the diploid condition again
Haploid
Diploid

30. Sperm formation- 4 haploid sperm cells are formed.
Egg formation-most of the cytoplasm is used in one cell and the other three disintegrate. One haploid egg cell is formed.

31. Meiosis
Video Clip

32. Crossing Over
Sometime during meiosis the chromosomes can exchange information
This is called Crossing Over
Major source of genetic diversity in the species

34. Prokaryotic Cells Binary fission Occurs in Prokaryotic Cells
DNA is copied and then the cell splits in half.

35. Regulation of the Cell Cycle
How do cells know when to divide? When to stop dividing?
Cyclins-proteins that regulate the cell cycle
When cells grow and then come into contact with each other they should stop growing.

36. Cancer Unregulated cell growth.
Can form masses of cells called tumors.