1. Cell Division Chapter 3.1

2. Do Now What happens when you get cut? Explain in your own words what happens when you are cut and the healing process.

3. Cell division occurs in all organisms –Unicellular organisms (ex: bacteria) Binary fission –Multicellular organisms (ex: US!) Mitosis

4. Cells needs a high surface area to volume ratio 1.All organisms start as a single cell a)Growth- limited by surface area (needs high ratio of surface area to volume) b)High SA allows nutrients in & waste out

5. Why do we need cell division? It is involved in many functions! 1.Growth – get bigger 2.Development – change 3.Repair – fix damaged or old cells 4.Reproduction – make new cells

6. DNA – deoxyriobonucleic acid A chemical that contains information for an organism’s growth and functions. Double helix like a twisted ladder

7. Chromosomes In Eukaryotic cells, DNA is found in the nucleus DNA is wrapped around proteins like thread around a spool, compacted into structures called chromosomes.

8. We have 46 total chromosomes= 23 pairs

9. Question Even when you are done growing and development appears to stop, is cell division still occurring?

10. Growth In general, large organisms do not have larger cells than smaller organisms. Simply, they just have more cells. As an adult, you have about 100 trillion cells!

11. Development During development, cells become specialized to perform particular functions. These cells may take on shapes or structures that help them perform their functions.  Some become skin cells, nerve cells, etc.  These cells have the same genetic material  Some become skin cells, nerve cells, etc.  These cells have the same genetic material

12. Repair 78 The body repairs body injuries through cell division. Ex: cut on skin or broken leg As cells age and die, they need to be replaced. We are made up of 200 different types of cells Every minute, you lose 40,000 skin cells! Brain cells live long and do not divide often

13. Surface area to volume http://www.brown.edu/Courses/BI0020_Miller/ week/10/web-1/4-2-2007_10-20- 26/Chapter_41/Present/Animations/41_A01/41 _A01s.htmlhttp://www.brown.edu/Courses/BI0020_Miller/ week/10/web-1/4-2-2007_10-20- 26/Chapter_41/Present/Animations/41_A01/41 _A01s.html Multicellular division http://www.youtube.com/watch?v=AhgRhXl7w _ghttp://www.youtube.com/watch?v=AhgRhXl7w _g Unicellular division: http://www.youtube.com/watch?v=J6akNYlke hYhttp://www.youtube.com/watch?v=J6akNYlke hY