1. Mitosis & Cytokinesis

2. Why do Eukaryotic cells divide by Mitosis?
Growth & Repair for multicelled organisms
Reproduction of single celled organisms
Amobea
Reproducing

3. Cells dividing by Mitosis…….
Skin
Identical to original cell
Same chromosome #
Identical chromosome makeup

4. What are chromosomes? A chromosome is an organized structure of DNA and protein that is found in cells. It is a single piece of coiled DNA containing many genes, regulatory elements and other nucleotide sequences.

5. What are chromosomes? A chromosome is an organized structure of DNA and protein that is found in cells. It is a single piece of coiled DNA containing many genes, regulatory elements and other nucleotide sequences.

6. What are chromosomes? A chromosome is an organized structure of DNA and protein that is found in cells. It is a single piece of coiled DNA containing many genes, regulatory elements and other nucleotide sequences.
Sister Chromatids

7. So where is DNA located?
In the Nucleus
In the Chromosomes

8. Cell division requires coordinated division of chromosomes (mitosis) …..
…… and division of the cytoplasm (cytokinesis).

9. From Birth to Rebirth, a Cell Progresses Through Characteristic Stages That Constitute the Cell Cycle.
In multicellular organisms like us, progress through the cell cycle is carefully regulated.

10. Stages of Mitotic Cell Division
Interphase - intermission
Prophase - 1st
Metaphase - middle
Anaphase - apart
Telophase – far or seperate

11. Interphase “Intermission” Normal metabolic activities Major state
DNA = chromatin

12. Late Interphase Prepares for mitosis DNA doubles = Sister chromatids
Centrioles double in animals

13. Prophase Nuclear membrane disappears Doubled DNA = condensed
“chromosomes” visible
Spindle fibers

14. Metaphase
Chromosomes line up mid- cell
Facing inward

15. Anaphase Chromosomes move to opposite poles at Centrioles in animals
Spindle apparatus in plants

16. Telophase
Cells divide
Cell plate or membranes form
Nucleus reappears

17. Cytokinesis: cell’s cytoplasm divides & splits apart

18. Plant versus Animal Mitosis
Cell wall from cell plate in telophase
Spindles
Animal:
No cell wall membrane during cytokinesis
Centrioles

19. In Animal Cells, a Cleavage Furrow Forms and Separates Daughter Cells
Cleave furrow in a dividing frog cell.

20. Animal Telophase
Interphase

21. The Plant Cell Wall Forces Cytokinesis to Play by Different Rules

22. Plant Anaphase
Interphase

23. Spindle & spindle fibers: Pull apart the sister chromatids

24. Returns to Interphase “Intermission” Normal metabolic activities
Major state
DNA = chromatin

25. DNA and Its Faithful Replication –
The Knit of Identity
Because DNA stores genetic information and is faithfully replicated, information is passed largely unaltered from cell-to-cell, generation-to- generation.

26. Proteins and Their Production – The Primary Reason for DNA

27. Cell Division Demands
Coordination of DNA Replication, Mitosis and Cytokinesis

28. DNA Replication – Simple in Principle, Complicated in Practice

29. DNA is Packaged into Chromosomes
chromatin
duplicated
chromosome
DNA in the cell is virtually always associated with proteins.
The packaging is impressive – 2 meters of human DNA fit into a sphere about meters in diameter.

30. The Link Between DNA Replication and Chromosome Duplication

31. 95% of the time, chromosomes are like this.
DNA is Condensed into Visible Chromosomes Only For Brief Periods in the Life of a Cell
95% of the time, chromosomes are like this.
(chromatin)
Easily visible chromosomes are apparent perhaps 5% of the time in an actively growing cell and less in a non-growing cell.

32. A Karyotype is an Arranged Picture of Chromosomes At Their Most Condensed State
Note that almost all chromosomes come in homologous pairs.
Boy or girl?
A normal human karyotype

33. From Birth to Rebirth, a Cell Progresses Through Characteristic Stages That Constitute the Cell Cycle
In multicellular organisms like us, progress through the cell cycle is carefully regulated.

34. The Knit of Identity - Mitosis Precisely and Evenly Divides Duplicated Chromosomes
interphase
prophase
metaphase
Precisely dividing the duplicated chromosomes has the consequence of providing each new cell with an identical and complete set of genetic instructions.

35. Mitosis Precisely and Evenly Divides Duplicated Chromosomes
Cytokinesis is the process of cell division and it is distinct and separable from mitosis.

36. Mitosis in Action
Blue shows DNA, green shows spindle fibers.

37. Cancerous cells……... 1.Divide too many times
2.Divide into more than two cells!
Masses of cells =
“tumors”
benign
malignant

38. Cancer Is One Outcome of A Runaway Cell Cycle
Licentious division - prostate cancer cells during division.