1. Growth & Development
Cell Reproduction

2. Why do cells have to divide?

3. 2 Reasons – 1. To grow 2. Replace old/damaged/dead cells

5. 2 Reasons – Surface area to volume ratio is an issue

7. What is the most important part of the cell that has to be divided?

9. A bunch of words for all the same stuff:
chromatids
chromatin
Chromatin

13. Chromosome # (Diploid)
Organism
Chromosome # (Diploid)
Buffalo 60
Lion 38
Llama 74
Donkey 62
Horse 64
Camel
Cow
Tiger
Cabbage, Broccoli, Cauliflower 18
Cockroach
23 or 24
Chimpanzee 48
Earthworm 36
Kangaroo 16
Mango 40
Human 46
How many chromosomes do we have?

16. Karyotype

18. CELL CYCLE Three parts: Then you do it all over again. Interphase
Mitosis
Cytokinesis
Then you do it all over again.

19. INTERPHASE Most of the cell’s life is spent here.
Divided into three parts: G1 S G2

20. INTERPHASE
G1 – Gap 1
Offspring cells grow to mature size.

21. INTERPHASE
S – Synthesis
The cell’s DNA is copied (synthesized).

22. INTERPHASE
G2 – Gap 2
More cell growth and preparation for cell division.

23. INTERPHASE
G0 – Gap 0
Cells can exit the cell cycle at G1 and go into G0. They stop preparation for division and do not divide.

24. MITOSIS Broken into 4 steps: Prophase Metaphase Anaphase Telophase
Video: A plant cell going through mitosis

25. MITOSIS 1st phase of mitosis DNA forms chromosomes
nuclear membrane breaks down
centrosomes move to opposite ends of the cell
spindle fibers start to form
Prophase

26. MITOSIS 2nd phase of mitosis chromosomes easy to see
Metaphase
2nd phase of mitosis
chromosomes easy to see
kinetochore fibers move chromosomes to the center of the cell

27. MITOSIS 3rd phase of mitosis chromatids separate at the centromere
Anaphase
3rd phase of mitosis
chromatids separate at the centromere
chromatids begin moving towards opposite sides

28. MITOSIS 4th phase of mitosis chromosomes reach opposite sides of cell
spindle fibers disassemble
chromosomes uncoil
nuclear membrane forms around the DNA
Telophase

29. CYTOKINESIS mitosis divides the nucleus
cytokinesis divides the cytoplasm
cleavage furrow pinches the cell in two using microfilaments
plats also need to form a cell plate

30. Animal and Plant Cell Cytokinesis

31. MITOSIS What’s the end result? ONE 2n* (diploid) cell produces
TWO identical 2n* (diploid) daughter cells
*”n” is considered haploid, or the number of unique chromosomes/chromosome pairs in a given species
“n” for humans is 23
“2n” for humans is 46

32. MITOSIS What’s the end result? ONE 2n (diploid) cell produces
TWO identical 2n (diploid) daughter cells

35. Controlling Cell Division
G1 checkpoint – proteins control division. If the cell is large and healthy, proteins initiate DNA synthesis
G2 checkpoint – DNA repair enzymes check the results of DNA synthesis. If everything is good, proteins will let mitosis begin.

36. When Control is Lost Cancer is uncontrolled cell division.
Mutations can cause increased amounts of growth promoting molecules or prevent proteins from slowing or stopping cell division.

38. When Control is Lost

39. When Control is Lost
Benign Malignant