1. Cell Division and Genetics – Mechanisms for a Knit of Identity and Thread of Distinction

2. 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.

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

4. Cell Division Demands Coordination of DNA Replication, Mitosis and Cytokinesis What’s so important about cell division (3 reasons)?

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

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

7. DNA is Packaged into Chromosomes DNA in the cell is virtually always associated with proteins. The packaging is impressive – 2 meters of human DNA fit into a sphere about 0.000005 meters in diameter. chromatin duplicated chromosome

8. The Link Between DNA Replication and Chromosome Duplication

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

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

12. 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.

13. The Cell Cycle Events that occur in the life of a cell. Includes 3 major stages: 1.Interphase 2.Mitosis 3.Cytokinesis

15. 1. Interphase (Cell is not dividing)  G 1 Phase – carries out basic functions & performs specialized activities.  duration is extremely variable  contains restriction checkpoint ~ cell “decides” to:  divide  enter a quiescent phase (G 0 )  die

17. 1. Interphase (Cell is not dividing)  G 0 Phase – cell maintains specialized characteristics, but does not divide Ex. neurons & muscle cells

19. 1. Interphase (Cell is not dividing)  S Phase – cell replicates chromosomes & synthesizes proteins  animal cells replicate centrioles as well

22. 1. Interphase (Cell is not dividing)  G 2 Phase - cell synthesizes additional proteins (ex. tubulin) & assembles/stores membrane material

24. 2.Mitosis (M phase) – Equal distribution of replicated genetic material.  Four steps:  Prophase  Metaphase  Anaphase  Telophase

25. 2.Mitosis – Prophase  replicated chromosomes condense  centrosomes separate & migrate toward opposite sides of cell  mitotic spindle forms (microtubules grow out from centrosomes)  nucleolus and envelope disappear

27. 2.Mitosis – Late Prophase (prometaphase)  nuclear membrane breaks down  spindle fibers attach to centromeres of chromosomes

29. 2.Mitosis – Metaphase  chromosomes are lined up single-file along equator of mitotic spindle

31. 2.Mitosis – Anaphase  Centromeres part, sister chromatids (now called chromosomes) separate  chromosomes move toward opposite poles  ?

33. 2.Mitosis – Telophase  mitotic spindle breaks down  chromosomes decondense  nuclear membranes reform around two nuclei  nucleoli reappear

35. 3.Cytokinesis  Distribution of cytoplasm to daughter cells  begins during anaphase or telophase  differs in animal & plant cells

37. 3.Cytokinesis in animal cells  Cleavage furrow (slight indentation) forms around equator of cell  Actin & myosin microfilaments act like a drawstring to pinch the cell in two  Usually an equal division

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

40. Review of the M-phase

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