1. Mitosis Chapter 12

2. Mitosis Cell division Produce 2 daughter cells
Same genetic information
Genome

3. Mitosis
Asexual reproduction
Growth
Repair

4. Prokaryotes
Nucleoid
Circular DNA
No nucleus

5. Eukaryotes Chromosomes: DNA Chromatin: Complex of DNA & proteins
Makes up chromosomes
Humans 46 chromosomes
Dogs 78 chromosomes

6. Karyotype
Display of the chromosomes

7. Karyotype

8. Turners syndrome

9. Eukaryotes Haploid(n): Single set of chromosomes (23 in humans)
Diploid(2n):
Twice the haploid number or two sets (46)
Homologous chromosomes:
2 chromosomes that match up
One from the mother one from the father
Homologs:
One of the pair of chromosomes

10. Eukaryotes Chromatid: Duplicated chromosome Centromere:
                                                     
Chromatid:
Duplicated chromosome
Centromere:
Attachment to another chromatid
Prior to cell division each chromosome replicates

11. S (DNA synthesis) G1 Cytokinesis G2 Mitosis
Fig. 12-5
INTERPHASE S
(DNA synthesis) G1
Cytokinesis G2
Mitosis
Figure 12.5 The cell cycle
MITOTIC
(M) PHASE

12. Cell cycle Cell cycle: Events that occur to produce two cells
1. Interphase (G1, S, G2)
2. Mitosis
3. Cytokinesis

13. Cell cycle Most of cycle is spent in interphase
Rate of division depends on job of the cell.
Liver cells may divide rapidly
Mature muscle cells do not divide at all
Few cells will be in mitosis at a time
Most are in interphase

14. Cell cycle G1 or Gap 1 phase the cell is preparing for the S phase.
Chromosomes are single
Can last weeks to years or happen very quickly

15. Cell cycle S phase DNA replication happens 2 sister chromatids
G2 or Gap 2 phase cell prepares for division
Mitochondria & other organelles replicate
Microtubules begin to form
Chromosomes condense

16. Cell cycle Mitosis: Nucleus & its contents divide Distributed equally
Forming two daughter cells
Cytokinesis:
Cytoplasm divides in two.

18. Interphase
Growth phase of the cell
G1, S, G2

19. Interphase

20. Prophase Beginning of mitosis Chromosomes continues to condense
Mitotic spindle forms
Begins to move chromosomes to center
Nuclear membrane disintegrates
Nucleolus disappears

21. Prophase

22. Metaphase Chromosomes line up in center of cell
Centromeres become aligned along the cells center

23. Metaphase

24. Anaphase Microtubules shorten Separates the sister chromatids
Chromosomes move towards the poles

25. Anaphase

26. Telophase Chromosomes are at the poles Nuclear envelope reforms
Nucleolus reappears
Chromosomes uncoil or de-condense

27. Telophase

28. Cytokinesis Cytoplasm separates Animal cells:
cleavage furrow pinches the cells in two
Plant cells:
cell plate is formed between the cells
Grows until a new cell wall is formed

29. Cytokinesis

30. Figure 12.9 Cytokinesis in animal and plant cells
Vesicles
forming
cell plate
Wall of
parent cell
1 µm
100 µm
Cleavage furrow
Cell plate
New cell wall
Figure 12.9 Cytokinesis in animal and plant cells
Contractile ring of
microfilaments
Daughter cells
Daughter cells
(a) Cleavage of an animal cell (SEM)
(b) Cell plate formation in a plant cell (TEM)

31. Binary fission
Prokaryotes produce 2 daughter cells by binary fission

32. Binary fission 1. Replication of the DNA Origin of replication:
Specific location on the DNA
2. Two DNA molecules move to the ends of the cell
3. Septation
Formation of a new cell membrane & a septum.

33. Binary fission 4. Septum begins to grow inward
5. Cell pinches into two cells.

34. Cell cycle

35. Cell cycle control system
Consists of special proteins
Protein kinases & cyclins
Regulate if cell stops or proceeds in the cycle
Receives information from the environment
Other cells determine if the cell should divide or not

36. Cell cycle control system
Check points
G1, G2 and M
Signals
Growth factors
Density-dependent inhibition
Anchorage dependence

37. G1 checkpoint Control system S G1 G2 M M checkpoint G2 checkpoint
Fig
G1 checkpoint
Control
system S G1 G2 M
Figure Mechanical analogy for the cell cycle control system
M checkpoint
G2 checkpoint

38. p53 Protein that works at a checkpoint at G1 in the cell cycle
p53 determines if the DNA is damaged
If so it stimulates enzymes to fix it
Cell division continues
Unable to repair damage
Cell suicide occurs

39. p53 Helps keep damaged cells from dividing
Cancer cells p53 is absent or damaged
p53 protein is found on the p53 gene
Considered a tumor-suppressor gene
Cigarette smoking causes mutations in this gene

40. Tumor Abnormal growth of cells
Due to a malfunction in the control system
Abnormal cells grow uncontrollably
Benign:
Non-cancerous growth

41. Tumor Malignant: Cancerous growth Metastasis:
Spread of cancer to distant locations

42. Henrietta Lacks 1951 developed cervical cancer Before cancer treatment
Cells were removed
First cells to grow in vitro
Outside of the body
Cell line is now known as the HeLa cell line
Helped in biomedical research