1. Life Cycle
of a
Cell

2. Unit Goals Describe the phases of the cell cycle.
Describe the process of Mitosis.
Describe the functions of mitosis.
Describe the process of Meiosis.
Describe the functions of meiosis.
Explain the consequences of mistakes.

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

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

5. Sex cells are called gametes
Regular Cells
Interphase
Somatic cell cycle 
G1 phase- Gap phase, cell undergoes growth.
S phase- DNA synthesis
G2 phase- Gap phase. Preparation for Mitosis. Organelles are produced.
M phase- Cell division (Mitosis and cytokinesis)
Sex cells are called gametes

6. G1 Phase
Cell Grows

7. S Phase Chromosomes Condense
Chromosomes are inherited genetic information
Chromosomes are made up of DNA
Can only be seen when cells are dividing

8. S Phase Chromosomes replicate-or copy is made The two copies are
When a cell divides, its two daughter cells must receive the required number of DNA molecules.
Chromosomes replicate-or copy is made
The two copies are
-attached together at a point called a centromere.
-are called sister chromatid.

10. Organelles must be replicated (copied)
G2 Phase
Organelles must be replicated (copied) 9

11. M Phase Two parts: Nuclear division Cytoplasmic Division Mitosis
Saturday, April 22, 2017
Two parts:
Nuclear division
Mitosis
Cytoplasmic Division
Cytokinesis 10

12. 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.

13. 4 Steps of Mitosis (PMAT)
 Prophase: Chromosomes condense and attach to the spindle fibers at their centromere.
Nuclear
Membrane
breaks down.

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

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

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

17. 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

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

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

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

24. Results of Mitosis and Cytokinesis
Two new cells.
The new cells- called daughter cells- have the same number of chromosomes as the mother cell.

25. Results of Mitosis and Cytokinesis
This occurs in all somatic cells in your body.
You have 46 chromosomes in all of your somatic cells-23 pair!

26. Mitosis in Onion

27. Cells
during
Mitosis

30. Concept Map 29 Cell Cycle includes M phase (Mitosis) Interphase
is divided into
is divided into
G1 phase
S phase
Prophase
G2 phase
Metaphase
Telophase
Anaphase

31. Meiosis: Reproduction of Sex Cells30
Sex cells- Sperm and egg
Process is called Meiosis
Similar to Mitosis
Meiosis Introduction Clip

32. Meiosis Cell divides twice31
DIPLOID= 2 copies)
Cell divides twice
First division is like mitosis and then the cell divides again to create 4 haploid cells.
Not genetically identical!
Contains ½ (HAPLOID) of the genetic information.

33. Not genetically identical! Contains ½ of the genetic information.
31.2
Not genetically identical!
Contains ½ of the genetic information.

34. MEIOSIS=CHROMOSOME REDUCTION DIVISION
Not genetically identical!
Contains ½ of the genetic information.

35. Meiosis Meiosis is also know as chromosome reduction division.
Meiosis Square Dance
Meiosis is also know as chromosome reduction division.
In Humans, starts with 46 and ends up with 23.
Why?
Fertilization creates the diploid condition again
Haploid
Diploid

36. 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.

37. Meiosis
Video Clip

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

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

41. Regulation of the Cell Cycle
How do cells know when to divide?
When to stop dividing?
Cyclins-proteins that regulate the cell cycle.

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

43. REVIEW CLIP