2. Regents Biology Do cells grow larger to increase the overall size of an organism????

3. Regents Biology Biology is the only subject in which multiplication is the same thing as division… 2006-2007

4. Regents Biology MITOSIS: Making New Cells Making New DNA

5. Regents Biology Where it all began… We all start as a cell smaller than a period at the end of a sentence…

6. Regents Biology And now look what can happen… How did you get from there to here?

7. Regents Biology  Going from egg to baby…. the original fertilized egg has to divide… and divide… Getting from there to here…

8. Regents Biology Limits to Cell Growth ? Do cells grow larger to increase an organism’s size? NO!! Why? 1) DNA - cell parts rely on DNA for instructions - increase in size = more parts needing info * DNA has a limit on ability to send out instructions

9. Regents Biology 2) Movement of Materials - increase in size = larger volume (inner space) less surface area (cell membrane) Therefore: - materials get crowded moving in/out of cell Example:1cm x 1cm cell3cm x 3cm cell Surface Area =1cm x 1cm x 6 sides3cm x 3cm x 6 = 6 cm 2 = 54 cm 2 Volume = 1cm x 1cm x 1cm 3cm x 3cm x 3cm = 1cm 3 = 27 cm 3 Ratio =6 to 12 to 1

10. Regents Biology Solution - Cell division increases the number of cells which increases the organism’s size.

11. Regents Biology Why else do cells divide…  One-celled organisms 1. for reproduction 2. asexual reproduction (clones)  Multi-celled organisms 1. for growth & development  from fertilized egg to adult 2. for repair & replacement  replace cells that die from normal wear & tear or from injury amoeba starfish

12. Regents Biology Dividing cells…  What has to be copied  DNA  organelles  cell membrane  lots of other molecules  enzymes animal cellplant cell

13. Regents Biology Genetic Material Involved 1) Chromatin - thin strands of DNA that can form into chromosomes. 2) Chromosomes - thick rod shaped structures that carry DNA to new cells.

14. Regents Biology double-stranded human chromosomes ready for mitosis

15. Regents Biology Chromosomes of Human Female 46 chromosomes 23 pairs

16. Regents Biology Chromosomes of Human Male 46 chromosomes 23 pairs

17. Regents Biology Cell Cycle: Life Cycle of Cells  Stage 1: cell copies DNA nucleus cell DNA interphase

18. Regents Biology Cell Cycle

19. Regents Biology Mitosis: Dividing DNA & cells  Stage 2: DNA winds up into chromosomes  DNA is wound up into chromosomes to keep it organized nucleus cell duplicated chromosomes ( prophase)

20. Regents Biology Mitosis: Dividing DNA & cells  Stage 3: Chromosomes line up  chromosomes line up in middle  attached to protein “cables” that will help them move duplicated chromosomes lined up in middle of cell metaphase

21. Regents Biology Mitosis: Dividing DNA & cells  Stage 4: Chromosomes separate  chromosomes split, separating pairs  start moving to opposite ends chromosomes split & move to opposite ends anaphase

22. Regents Biology Mitosis: Dividing DNA & cells  Stage 5: Cell starts to divide  cells start to divide  nucleus forms again Telophase - animals- cell pinches in - plants- cell plate forms

23. Regents Biology Mitosis: Dividing DNA & cells  Stage 6: DNA unwinds again  cells separate  now they can do their every day jobs cytokinesis

24. Regents Biology New “daughter” cells  Get 2 exact copies of original cells  same DNA  “clones”

25. Regents Biology Cell division in Animals

26. Regents Biology Mitosis in whitefish embryo

27. Regents Biology Mitosis in plant cell

28. Regents Biology onion root tip

29. Regents Biology Overview of mitosis interphaseprophase metaphaseanaphasetelophase cytokinesis I.P.M.A.T.C. P lease M ake A nother T wo C ells