The document discusses the process of cell division through mitosis. It begins with how a single fertilized egg cell multiplies through repeated cell division to form a multicellular organism. It then explains the steps cells take to duplicate their DNA and divide, including DNA replication, chromosome formation, and the stages of mitosis - prophase, metaphase, anaphase, telophase and cytokinesis. The end result is two daughter cells that are identical clones of the original parent cell.

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

2. Making New Cells Making New DNA 2006-2007

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

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

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

6. Why do cells divide… for reproduction one celled organisms (clones) for growth & development from fertilized egg to multi-celled organism for repair replace cells that die from normal wear & tear or from injury amoeba starfish

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

9. Organizing & packaging DNA nucleus cell DNA nucleus cell 4 chromosomes in this organism DNA in chromosomes in everyday “working” cell DNA in chromosomes in cell getting ready to divide DNA has been “wound up”

10. Chromosomes of Human Female 46 chromosomes 23 pairs

11. Chromosomes of Human Male 46 chromosomes 23 pairs

12. Paired bases DNA structure double helix 2 sides like a ladder Bases match together A pairs with T A : T C pairs with G C : G

13. Watson and Crick

14. Copying DNA Matching bases allows DNA to be easily copied

15. Making new DNA Copying DNA replication DNA starts as a double-stranded molecule matching bases (A:T, C:G) then it unzips…

16. DNA replication Strands “unzip” at the weak bonds between bases

17. DNA replication Enzyme DNA polymerase adds new bases DNA polymerase DNA bases in nucleus

18. Copying DNA DNA Polymerase Build daughter DNA strand use original parent strand as “template” add new matching bases synthesis enzyme = DNA polymerase

19. New copies of DNA Get 2 exact copies of DNA to split between new cells DNA polymerase DNA polymerase

20. Copied & Paired Up Chromosomes

21. 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

22. double-stranded human chromosomes ready for mitosis

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

24. Mitosis: Interphase Dividing DNA & cells Stage 1: cell copies DNA nucleus cell DNA Copy DNA!

25. Mitosis: Prophase Stage 2: DNA winds into chromosomes DNA is wound up into chromosomes to keep it organized nucleus cell duplicated chromosomes Wind up!

26. Mitosis: Metaphase 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 Meet In Middle!

27. Mitosis: Anaphase Stage 4: Chromosomes separate chromosomes split, separating pairs start moving to opposite ends chromosomes split & move to opposite ends Apart!

28. Mitosis: Telophase Stage 5: Cell starts to divide cells start to divide nucleus forms again Divide!

29. Mitosis: Cytokinesis Stage 6: DNA unwinds again cells separate now they can do their every day jobs

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

31. Cell division in Animals

32. Mitosis in whitefish embryo

33. Mitosis in plant cell

34. onion root tip

35. Overview of mitosis Copy DNA Wind Up Meet in Middle Apart Divide

36. 2006-2007 Any Questions?? Any Questions??