2. MITOSIS: Making New Cells Making New DNA

3. Where it all began…
You started as a cell smaller than a period at the end of a sentence…

4. How did you get from there to here?
And now look at you…
How did you get from there to here?

5. Getting from there to here…
Going from egg to baby….
the original fertilized egg has to divide…
and divide…

6. Why do cells divide… One-celled organisms Multi-celled organisms
for reproduction
asexual reproduction (clones)
Multi-celled organisms
for growth & development
from fertilized egg to adult
for repair & replacement
replace cells that die from normal wear & tear or from injury
amoeba
starfish
Unicellular organisms
Cell division = reproduction
Reproduces entire organism& increase population
Multicellular organisms
Cell division provides for growth & development in a multicellular organism that begins as a fertilized egg
Also use cell division to repair & renew cells that die from normal wear & tear or accidents

7. Dividing cells… What has to be copied DNA organelles cell membrane
lots of other molecules
enzymes
plant cell
animal cell

8. Copying DNA A dividing cell duplicates its DNA
creates 2 copies of all DNA
separates the 2 copies to opposite ends of the cell
splits into 2 daughter cells
But the DNA starts loosely wound in the nucleus
If you tried to divide it like that, it could tangle & break
DNA
cell
nucleus

9. Organizing & packaging DNA
cell
nucleus
DNA has been “wound up”
DNA in chromosomes in everyday “working” cell
cell
nucleus
chromosomes in this organism
DNA in chromosomes in cell getting ready to divide

10. Chromatin - condensed single strand DNA
Chromosome – condensed DNA bound in the center by a centromere
centromere
chromatin
chromatid
Chromatin - condensed single strand DNA
Chromatid – each strand of doubled chromosome

11. Chromosomes of Human Female
23 pairs

12. Chromosomes of Human Male
23 pairs

13. Copying & packaging DNA
When cell is ready to divide…
copy DNA first, then…
coil up doubled chromosomes like thread on a spool…
now can move DNA around cell without having it tangle & break
Copying DNA
Coil DNA into compact chromosomes

14. double-stranded human chromosomes
ready for mitosis

15. DNA must be duplicated…
chromosomes in cell
4 single-stranded chromosomes
nucleus
cell
DNA in chromosomes
nucleus
cell
duplicated chromosomes
duplicated
chromosomes
4 double-stranded chromosomes

16. Mitosis: Dividing DNA & cells
Stage 1: cell copies DNA
Cell growth
DNA replicates
Centrioles replicate and go to opposite sides of the cell
Divided into 3 parts
G1, S, G2
DNA
cell
nucleus
(interphase)

17. Time Span Cyclin A protein that determines the cell cycle
Cyclin increases until it reaches a certain point then cell starts mitosis

18. Mitosis: Dividing DNA & cells
Stage 2: DNA winds into chromosomes
DNA is wound up into chromosomes to keep it organized
duplicated chromosomes
Wind up!
cell
nucleus
(prophase)

19. Mitosis: Dividing DNA & cells
Stage 3: Chromosomes line up
chromosomes line up in middle
attached to protein “cables” that will help them move
Line up!
duplicated chromosomes
lined up in middle of cell
(metaphase)

20. Mitosis: Dividing DNA & cells
Stage 4: Chromosomes separate
chromosomes split, separating pairs
start moving to opposite ends
Separate!
chromosomes split & move to opposite ends
(anaphase)

21. Mitosis: Dividing DNA & cells
Stage 5: Cell starts to divide
cells start to divide
nucleus forms again
Divide!
(telophase)

22. Mitosis: Dividing DNA & cells
Stage 6: DNA unwinds again
cells separate
now they can do their every day jobs
Bye Bye!
(cytokinesis)

23. New “daughter” cells Get 2 exact copies of original cells same DNA
“clones”

24. Cell division in Animals

25. Mitosis in whitefish embryo

26. Mitosis in plant cell

27. onion root tip

28. Please Make Another Two Cells
I.P.M.A.T.C.
Overview of mitosis
interphase
prophase
Please Make Another Two Cells
cytokinesis
metaphase
anaphase
telophase

29. Any Questions??

30. Asexual Reproduction Binary Fission Budding
organism divides into 2 equal parts
Ex: bacteria, protozoan
Budding
Parent divides into 2 unequal parts
Ex: yeast, Hydra

31. Vegetative Propagation
Spores
Thickly coated cells
Ex: Mold
Regeneration
Ability to regrow lost body parts
Ex: Planaria
Vegetative Propagation
Using roots, stems, and leaves to make a new plant

32. Mitosis & Cancer: When Making New Cells Goes Terribly Wrong!

33. When is mitosis a good thing?
When you have to add or replace cells
growth & development
repair
replacement

34. When is mitosis a BAD thing
When cells reproduce & they are not needed
these cells take over organs, but don’t do the right job
they just keep making copies
cancer
damages organs

35. Why would cells just make copies?
If DNA gets damaged, cells stop listening to correct instructions
Mutations - carcinogens
Causes of mutations:
UV radiation
chemical exposure
radiation exposure
heat
cigarette smoke
pollution
age
genetics

36. Tumors Benign tumor abnormal cells remain at original site as a lump
most do not cause serious problems & can be removed by surgery

37. Tumors Malignant tumor cells leave original site
carried by blood system to other tissues
start more tumors
damage functions of organs throughout body

38. Treatments for cancers
side effects
Treatments for cancers
Treatments kill rapidly dividing cells
chemotherapy
poisonous drugs that kill rapidly dividing cells
radiation
high energy beam kills rapidly dividing cells

39. Any Questions??