2. AP Biology 2007-2008 Tour of the Cell Part 2

3. AP Biology From food to making Energy  Cells must convert incoming energy to forms that they can use for work  mitochondria: from glucose to ATP  chloroplasts: from sunlight to ATP & carbohydrates  ATP = immediate energy  carbohydrates = stored energy + ATP

4. AP Biology Mitochondria & Chloroplasts  Important to see the similarities  transform energy  generate ATP  double membranes = 2 membranes  semi-autonomous organelles  move, change shape, divide  internal ribosomes, DNA & enzymes Lynn Margulis U of M, Amherst

5. AP Biology Membrane-bound Enzymes glucose + oxygen  carbon + water + energy dioxide C 6 H 12 O 6 6O 2 6CO 2 6H 2 OATP  +++

6. AP Biology Membrane-bound Enzymes + water + energy  glucose + oxygen carbon dioxide 6CO 2 6H 2 O C 6 H 12 O 6 6O 2 light energy  +++

7. AP Biology Mitochondria are everywhere!! animal cells plant cells

8. AP Biology Cells gotta live!  What jobs do cells have to do?  building proteins  proteins control every cell function  make energy  for daily life  for growth  build more cells  growth  reproduction  repair

9. AP Biology Cytoskeleton  Function  structural support  maintains shape of cell  provides anchorage for organelles  protein fibers microfilaments, intermediate filaments, microtubules  motility  cell locomotion  cilia, flagella, etc.  regulation  organizes structures & activities of cell

10. AP Biology  actin  microtubule  nuclei Cytoskeleton

11. AP Biology Centrioles  Cell division  in animal cells, pair of centrioles organize microtubules  guide chromosomes in mitosis

12. AP Biology 2007-2008 Cell Size

13. AP Biology Limits to cell size  Lower limit  smallest bacteria  mycoplasmas  0.1 to 1.0 micron (µm = micrometer)  most bacteria  1-10 microns  Upper limit  eukaryotic cells  10-100 microns  micron = micrometer = 1/1,000,000 meter  diameter of human hair = ~20 microns

14. AP Biology What limits cell size?  Surface to volume ratio  as cell gets bigger its volume increases faster than its surface area  smaller objects have greater ratio of surface area to volume 6:1~1:16:1 s:v Why is a huge single-celled creature not possible?

15. AP Biology Limits to cell size  Metabolic requirements set upper limit  in large cell, cannot move material in & out of cell fast enough to support life CHO aa CH CO 2 NH 3 aa O2O2 CH What’s the solution? What process is this? O2O2 O2O2 aa CHO aa CH O2O2 aa CHO CH aa O2O2 CO 2 NH 3 CO 2 NH 3

16. AP Biology How to get bigger?  Become multicellular (cell divides) O2O2 CHO aa CH CO 2 NH 3 aa O2O2 CH But what challenges do you have to solve now? aa CO 2 NH 3 O2O2 aa CH aa CHO O2O2

17. AP Biology Phospholipid Cholesterol Membrane proteins Cell membrane  Exchange structure  plasma membrane functions as selective barrier  allows passage of O 2 & nutrients IN  allows passage of products & wastes OUT

18. AP Biology 2007-2008 Any Questions??