1. Cells Intro Defining Life Cell Theory Cell Size Prokaryotic vs. Eukaryotic Animal vs. Plant Organelles Magnification

2. Defining Life Does it grow? Does it reproduce? Does it use energy? Does it respond to environmental stimuli? Does it have order? Does it regulate its internal environment? Does it show evidence of evolutionary adaptation?

3. Cell Theory All living organisms are composed of cells.  Multicellular organisms (example: humans) are composed of many cells  Unicellular organisms (example: bacteria) are composed of only one cell. Cells are the smallest unit of life. They are the smallest structures capable of surviving on their own.  See previous slide Cells come from pre-exsisting cells and cannot be created from non-living material.  Gooseneck flask experiment

4. Evidence for Cell Theory No such thing as spontaneous generation Pasteur’s experiment

5. Cell Size Surface area of cell responsible for exchange of nutrients and waste products Volume of cell responsible for cellular functions (e.g. cell respiration)

6. Volume Volume determines the amount metabolism in the cytoplasm Metabolism will require import of precursors Metabolism will result in the export of secretions And the export of excretory products © 2007 Paul Billiet ODWSODWS

7. Surface area Surface area will determine the exchange of materials between the cell and its environment Bigger cells will metabolise more But they will need more surface to support that metabolism And the sites of metabolism in bigger cells will be further from the surface of the cell © 2007 Paul Billiet ODWSODWS

8. Growing cells 1µm 2µm 3µm 4µm 5µm 6µm © 2007 Paul Billiet ODWSODWS

9. How are surface area and volume affected by growth? 11.21.5236 216125642781 2161509654246 654321 SA/V Volume / µm 3 Surface area / µm 2 Size / µm © 2007 Paul Billiet ODWSODWS

10. Comparing Surface Area and Volume changes © 2007 Paul Billiet ODWSODWS

11. Surface Area:Volume Ratio © 2007 Paul Billiet ODWSODWS

12. Solving the problem Bigger cells have a greater metabolism than smaller cells BUT bigger cells have a proportionally less surface for exchange How to increase surface area with increasing size? © 2007 Paul Billiet ODWSODWS

13. Throw out extensions Microvilli of small intestine epithelium © copyright 2001 Gwen V. Childs, Ph.D., University of Arkansas for Medical Sciences

14. Flatten into a thin film Chick blastodisc © Developmental Biology OnlineDevelopmental Biology Online © Developmental Biology OnlineDevelopmental Biology Online

15. Divide the cytoplasm into smaller volumes Early human embryos Zygote 8-cell Embryo © Reproductive Medicine and Fertility Center

16. Multicellular organisms show the same adaptations Flowering plants have an extensive, branched rooting system to absorb water and minerals © Illinois Enviromental Protection AgencyIllinois Enviromental Protection Agency © Text 2007 Paul Billiet ODWSODWS

17. Multicellular organisms show the same adaptations Mammals have a long small intestine with internal folding to absorb digested food lithograph plate 20th U.S. edition of Gray's Anatomy of the Human Body, originally published in 1918. This image is in the public domain because its copyright has expired © Text 2007 Paul Billiet ODWSODWS

18. Prokaryotic vs. Eukaryotic Prokaryotic cells  No nucleus  Circular DNA  No histone proteins  No membrane bound organells  Simple ribosomes Eukaryotic cells  Nucleus  Linear DNA (chromosomes)  Histone proteins  Membrane bound organelles  Complex ribosomes

19. Animal vs. Plant In animals but not plants:In plants but not animals: LysosomesCell Wall CentriolesCentrosomes FlagellaChloroplasts Central Vacuole

20. Organelles http://library.thinkquest.org/12413/structures.html

21. Magnification Magnification = Size of image(Units must be the same) Actual size If a red blood cell has a diameter of 8 μm and a student shows it with a diameter of 40 mm in a drawing, what is the magnification of the drawing? A.× 0.0002 B.× 0.2 C.× 5 D.× 5000