1. Cell Cycle

2. Chromosomes
Carry genetic information passed from one generation to the next.
Made of DNA
Human body cells have 46 chromosomes

3. Chromatids – identical parts of a chromosome “sister” chromatids
carry same info as chromosome
Centromere – area where chromatids are attached
Each new cell gets an exact copy of the original DNA so that each cell can function properly.
Sister chromatids
Centromere

4. Why do cells divide? Growth Replace damaged or old cells
Produce new individuals in single celled organisms

5. Cell Cycle (phases in the life of a cell)
During the cell cycle:
Growth
Preparing to divide
Division – two daughter cells are formed
Start cycle over
QUESTION: What is the goal?

6. Goal = To Make two Identical Daughter Cells
Parent Cell

7. The cell cycle consists of four phases:
G1 (First Gap Phase)
S Phase (Synthesis)
G2 (Second Gap Phase)
M Phase (Mitosis)

8. G1 Phase: (Gap phase 1) S phase (synthesis) Cell grows
synthesizes new proteins and organelles
S phase (synthesis)
chromosomes are replicated
DNA synthesis takes place

9. The G1, S, & G2 together are Interphase
G2 Phase (Gap Phase 2)
Final preparation for cell division
Makes organelles needed for mitosis
The G1, S, & G2 together are Interphase
M phase—Mitosis and Cytokinesis
- cell division
- division of the cytoplasm

10. Cell Cycle Interphase: Cell Division G0 G1, S, G2
Intermission from division; used to be called the resting stage, however, the cell is actually very active as it prepares to divide.
Cell Division
Mitosis – nucleus divides
Cytokinesis – cytoplasm divides G0
the cell stops dividing and specializes (gets a job)

12. I – P – M – A - T Mitosis Splitting of the nucleus
*Interphase (cell prepares to divide: G1, S, G2)
Prophase
Metaphase
Anaphase
Telophase
I – P – M – A - T

13. Remember: Goal = To Make two Identical Daughter Cells
Parent Cell

14. Interphase Cell prepares to divide G1 (First Growth)
S (Synthesis of DNA)
G2 (Second Growth)

15. Prophase 1st and longest Centrioles move to the poles
Spindle
forming
1st and longest
Centrioles move to the poles
Organize the spindle
Chromosomes condense
Nuclear envelope breaks down
Centromere
Chromosomes
(paired chromatids)
Copyright Pearson Prentice Hall

16. Metaphase Chromosomes line up across the middle of the cell
Centriole
Chromosomes line up across the middle of the cell
Spindles attach to centromeres
Spindle
Copyright Pearson Prentice Hall

17. Anaphase Chromatids separate Are pulled to the poles Individual
chromosomes
Chromatids separate
Are pulled to the poles
Copyright Pearson Prentice Hall

18. Telophase Opposite of Prophase Chromosomes lose shape
Nuclear envelope reforms
Spindles break down
Copyright Pearson Prentice Hall

19. Cytokinesis Splitting of the cytoplasm
Occurs at the same time as Telophase
Animal cell – pinches in (cleavage furrow)

20. Plant cell – a cell plate is formed
NO centrioles

21. Cell Cycle Regulation
Pg 250 Ch. 10-3

22. Controls on Cell Division
Experiments show that normal cells will reproduce until they come into contact with other cells.
When cells come into contact with other cells, they respond by not growing.

23. The controls of the cell cycle can be turned on and off

24. Cyclins: Proteins that regulate the timing of the cell cycle
Amount rises and falls with the cell cycle

25. Internal Regulators proteins that respond to events inside the cell
Act as checkpoints

26. External Regulators proteins that respond to events outside the cell
Cause the cell cycle to speed up or slow down

27. Cancer
Disorder in which the body’s cell lose the ability to control growth
Do not respond to cyclins
Divide uncontrollably – form tumors

28. Problem Solving Activity
Imagine that you are developing a drug that will inhibit the growth of cancer cells.
Use you knowledge of the cell cycle to describe how your drug would target and prevent the multiplication of cancer cells.