2. AP Biology 2007-2008 Cells create and maintain internal environments that are different from their external environment 2013 Cells Unit – Chapter 6

3. AP Biology Prokaryote bacteria cells Types of cells Eukaryote animal cells Eukaryote plant cells

4. AP Biology I. Why organelles?  Organisms must exchange matter with the environment to grow/communicate Cell membranes, golgi, vesicles  Exchange energy  unique combinations of lipids & proteins  embedded enzymes & reaction centers  chloroplasts & mitochondria  Maintain organization/homeostasis  partition cell into compartments  create different local environments  separate pH, or concentration of materials  distinct & incompatible functions  lysosome & its digestive enzymes, vacuoles mitochondria chloroplast Golgi ER

5. AP Biology II. Cell FUNCTION  What jobs do cells have to do?  communication  proteins control every cell function  make energy  for daily life  for growth  homeostasis  growth  reproduction  repair

6. AP Biology DNA Why study protein production? - communication/cell signaling cells proteins organism Repeat after me… DNA gets the glory, but Proteins do all the work!

7. AP Biology Protein Synthesis  Organelles are cooperative  nucleus  ribosomes  endoplasmic reticulum (ER)  Golgi apparatus  vesicles nucleusribosomeER Golgi apparatus vesicles The Protein Assembly Line

8. AP Biology DNA RNA ribosomes endoplasmic reticulum vesicle Golgi apparatus vesicle protein on its way! protein finished protein Making Proteins TO: nucleus TO:

9. AP Biology proteins transport vesicle Golgi apparatus vesicle smooth ER rough ER nuclear pore nucleus ribosome cell membrane protein secreted cytoplasm Transcription/Translation Putting it together…

10. AP Biology Cell Junctions Animal Cells  Tight junctions  Desmosomes  Gap Junctions Plant Cells Plasmodesmata Refer to the Campbell website Chapter 6 Activity Cell Junctions

11. AP Biology Cells FUNCTION  What jobs do cells have to do?  communication  proteins control every cell function  make energy  for daily life  for growth  homeostasis  growth  reproduction  repair ATP

12. AP Biology Cells need power! “Cell Respiration  Making energy  take in nutrients & digest it  take in oxygen (O 2 )  make ATP  remove waste ATP

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

14. 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

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

16. 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  +++ More membranes working together and efficiently

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

18. AP Biology Cells FUNCTION  What jobs do cells have to do?  communication  proteins control every cell function  make energy  for daily life  for growth  homeostasis  growth  reproduction  repair

19. AP Biology Lysosomes  Function  little “stomach” of the cell  digests macromolecules  “clean up crew” of the cell  cleans up broken down organelles  Structure  vesicles of digestive enzymes only in animal cells Where old organelles go to die!

20. AP Biology Lysosomal enzymes  Lysosomal enzymes work best at pH 5  organelle creates custom pH  how?  proteins in lysosomal membrane pump H + ions from the cytosol into lysosome  why?  enzymes are very sensitive to pH  why?  enzymes are proteins — pH affects structure  why is this an adaptation: digestive enzymes which function at pH different from cytosol?  digestive enzymes won’t function well if some leak into cytosol = don’t want to digest yourself!

21. AP Biology But sometimes cells need to die…  Lysosomes can be used to kill cells when they are supposed to be destroyed  some cells have to die for proper development in an organism  apoptosis – during development  “auto-destruct” process  lysosomes break open & kill cell  ex: tadpole tail gets re-absorbed when it turns into a frog  ex: loss of webbing between your fingers during fetal development  ex: self-destruct of cancerous cell

22. AP Biology Fetal development 15 weeks 6 weeks syndactyly

23. AP Biology When things go wrong…  Diseases of lysosomes are often fatal  digestive enzyme not working in lysosome  picks up biomolecules, but can’t digest one  lysosomes fill up with undigested material  grow larger & larger until disrupts cell & organ function  lysosomal storage diseases  more than 40 known diseases  example: Tay-Sachs disease build up undigested fat in brain cells

24. 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

25. AP Biology  actin  microtubule  nuclei Cytoskeleton

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

27. AP Biology 2007-2008 Effects of Cell Size

28. 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

29. 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?

30. AP Biology Why is cell size an issue?  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

31. 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

32. 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

33. AP Biology 2007-2008 Any Questions??