1. The Basics of Mitosis aka Asexual Reproduction
Important as a GUTS lecture for two reasons:
Although you’ve had it before, probably introduced as far back as middle school, it’s easy to forget and to understand it only in the broadest terms. I’ve found that typically we don’t understand (especially meiosis) until we sit down and draw out what happens to the chromosomes.
it’s of extraordinary importance. The mechanisms of inheritance and the patters we see in the heritibility of human disease and characteristics depend at their base on how meiosis works. Likewise, major diseases like cancer, hinge on aspects of mitosis.

2. What is Mitosis? IOW: Single Parent cell divides to produce two
Somatic cell (body cell) division consisting of nuclear division & cytoplasmic division (cytokinesis)
IOW: Single Parent cell
divides to produce two
identical daughter cells
a.k.a. Asexual Cell Reproduction
Called asexual because no combination of cellular material occurs – all new cells produced contain the same genetic material as the original cell.

3. “You cannot step twice into the same river”…Heraclitus of Ephesus, c
“You cannot step twice into the same river”…Heraclitus of Ephesus, c BCE
You literally are not the same person you were in the past
Cell division is required for
Growth & Development
Human zygote = 1 cell
Mature adult = 1 X 1014 cells
We wear out
Cell division is the primary manner in which we deal with the harmful effects of wear and damaging forces in our environment
Stem cells form a pool of self-renewing cells as “replacement parts”

4. What do all cells require to survive?
A complete set of Genetic Material or instructions in order to
produce required molecules
direct life processes
We need an orderly process to duplicate and distribute chromosomes through successive cell divisions

5. Genetic Material
The genetic material in a cell is DNA (deoxyribonucleic acid)
It is found in a different form depending on the stage of the cell cycle
Chromatin – long, thin threadlike material - present in this state during interphase
Chromosomes – small, sausage-like, may be found as a individual chromatids (late stages of cell division) or as paired chromatids (sisters) connected at the centromere.

7. All somatic cells contain homologous pairs of chromosomes - one from the mother’s egg (maternal chromosome) and one from the father’s sperm (paternal chromosome) – in the human, 23 sets (46 chromosomes total)
Each homologous pair is similar in shape and length and is responsible for the same types of characteristics
Sister chromatids are IDENTICAL to each other (exact copies)

9. Gene Chromosome DNA Gene = a segment of DNA that codes for a protein
Genes  You
Chromosome =
consists of DNA tightly
coiled around proteins

10. Diploid organisms receive one chromosome from their female parent (maternal chromosome) and one chromosome from male parent (paternal chromosome)
A “matched” pair of maternal and paternal chromosomes are called homologues
Humans - 23 pairs of homologous chromosomes
22 pairs of autosomes and 1 pair of sex chromosomes

11. Why pairs? Diploid = 2n Mom Dad Pair 1-22 = Autosomes Pair 23 = Sex
Gene 
 Gene
Gene 
 Gene
Pair 1-22 =
Autosomes
Gene 
 Gene
Gene 
 Gene
Pair 23 =
Sex
Chromosomes

12. Cell Cycle: Interphase: No Division
G1: hrs-cell grows in size & organelles replicated
S: 6-8 hrs-replication of DNA, synthesis of proteins associated with DNA
G2: 2-4 hrs-synthesis of proteins associated with mitosis (Centrioles stretch their legs!)

13. Interphase
(up to 90% of the cell cycle) – divided into three separate phases
G1 phase – (growth 1) – general growth & organelle replication, DNA consists of a single (unreplicated) chromatin molecule (46 strands)
S phase – (synthesis) – replication of chromosomal material (DNA)  2 copies of each chromosome (23 pairs in humans), can be identified by the uptake of a radioactive base
G2 phase (growth 2) – structures associated with mitosis & cytokinesis are replicated (cell membrane proteins, centrioles)

14. The Phases of Mitosis 4 phases: 1st – Prophase 2nd – Metaphase
3rd – Anaphase
4th – Telophase/Cytokinesis

15. 92
PMAT 46 46
Cytokinesis 46 46

16. Prophase Centrioles duplicated to form two pairs
chromatin
nucleus
centrioles
nucleolus
Centrioles duplicated to form two pairs
Chromosomes begin to condense

17. Prophase condensing chromosomes Nuclear envelope begins to break down
Spindle fibers form (specialized microtubules)
Radiate out from centrioles
forming the “aster”
One pair of centrioles migrates to
one pole of cell, the other pair
migrates to opposite pole of cell

18. The Mitotic Spindle Spindle fibers are specialized microtubules
Spindle fibers radiate out from centrioles forming the “aster”
Centrioles occur in pairs, and are duplicated during Prophase

19. Duplicated chromosome
Prophase
The Spindle Captures Chromosomes
When spindle fibers are fully formed, nuclear envelope disintegrates & nucleolus disappears
Spindle fibers attach to chromosomes at the kinetochore, a structure located at the centromere
Duplicated chromosome
(2 sister chromatids)

20. Prophase
Function of spindle fibers is to organize division of sister chromatids into daughter cells
Other spindle fibers do NOT attach to chromosomes, but retain free ends that overlap at cell’s equator > “free spindle fibers”

21. Metaphase
Chromosomes align along equator of the cell, with one kinetochore facing each pole
centrioles
chromosomes
spindle fibers

22. Anaphase Sister chromatids separate
Spindle fibers attached to kinetochores shorten and pull chromatids poleward
free spindle fibers lengthen and push poles of cell apart
The same number of single-copy chromosomes should be at each pole

23. Telophase Chromosomes decondense into Chromatin
spindle fibers disintegrate
pinching of cell membrane at equator
nuclear envelope reforms
nucleolus reappears

24. Animal Cell: ring contracts, dividing the cytoplasm
microfilaments attach to plasma membrane to form a ring around equator of cell (cleavage furrow)
cytokinesis
Animal Cell: ring contracts,
like a drawstring,
dividing the cytoplasm
Plant cells, a cell-plate forms first, separating the two cells by the forming cell wall
Daughter Cells

25. CYTOKINESIS
Animal
Plant
“Cleavage Furrow”
“Cell Plate”

27. 3 1
Prophase
Anaphase 4
Which?
Telophase 2
Metaphase 5
Interphase

28. Control of the Cell Cycle
90% time in Interphase
Feedback signals
– “red/green light”
Controlled by proteins

29. Cancer = uncontrolled growth/division of cells
If gene that contains info for cell growth/division is mutated =
Cell growth/division unregulated

30. Tumor “benign tumor” “malignant tumor” Metastasis- Therapy?-
= a mass of abnormal cells.
“benign tumor”
“malignant tumor”
Metastasis-
Start more tumors
Therapy?-
Radiation therapy
Chemotherapy with toxic drugs.
Mammograms 

32. END