1. Chromosomes and Cell Division

2. DNA Limits Cell Size
Cell cannot survive unless there is enough DNA to support the protein needs of the cell
In some really large cells are multi-nucleated
More nuclei = more DNA = quick, efficient protein manufacturing to meet large cell needs

3. Prokaryote Cell Division
Bacteria
Circular DNA
Reproduce by binary fission = 2 daughter cells
DNA copied
Know steps

4. Cell Reproduction Cell division—making 2 new cells from 1 parent cell
New cells are (and have to be) Genetically IDENTICAL
Why?
When?
Who?
How?

5. Eukaryotes —the Who Somatic cells—mitosis
Growth & replacement of lost, dead or damaged

6. Cell Cycle S: "synthesis" DNA replicates; 2 copies
G1: 1st growth phase major part
S: "synthesis" DNA replicates; 2 copies
S: "synthesis" DNA replicates; 2 copies
G2: 2nd growth phase; microtubules made
M: mitosis
C: cytokinesis2 daughter cells

7. G1 checkpoint—cell growth—are conditions favorable to divide (yes—S phase; no—rest or stop)
G2 checkpoint—enzymes edit and repair mistakes made during replication
M checkpoint—triggers exit from mitosis to begin G1

9. I P M A T C
I—I
P—put
M—my
A—arm
T—there
C—’cuz

10. DNA double stranded negative charge wraps around histones (+ proteins)
chromatid + centromere = chromosomes
DNA

12. Chromosomes
During mitosis
Super-coiled DNA
46 in somatic (body) cells
Contains 1000s of nucleotides
Contains 100s of genes
Small mistakes have major complications

14. Interphase Not mitosis… set up for mitosis centrioles replicate
DNA replicates & condenses

15. Prophase Chromosomes 1st visible
Centrioles move to poles & form spindle fibers
Nuclear envelope breaks down

16. Prophase in plants… Spindle fibers Disappearing nuclear envelope
Doubled chromosome

17. Metaphase "middle" centromere replicates
Chromosomes line up along the equator

18. Metaphase in Plants…
Centromere
Sister chromatids

19. Anaphase
chromatids pulled to poles
Pulled by spindle fibers

20. Anaphase in Plants…

21. Telophase and Cytokinesis
nuclear membrane reforms
spindle fibers disassembles
uncoiling of chromosomes
cleavage; membrane pinches in

22. Telophase in Plants… Cell plate forms Nuclear envelope reappears
Two daughter cells are formed

23. Differences in plants plants—cell plate forms
have asters not centrioles

24. Plant Mitosis

26. Why is mitosis important? What’s its purpose?
Growth and replacement of dead, lost and damaged cells
Ensures each daughter cell gets an complete and exact copy of the genetic material from the parent cell in the quickest, most efficient manner

27. Mitosis