1. Energy conversion: Fermentation

2. Announcements -No quiz during next week lab. session -Write an informal summary about today lab. I will discus this at the end of the lab. -Photosynthesis will be taught in 2 lab. session come prepared (as usual) and for the first week exercise; read the protocol at page 5-5 to 5-11

3. Today -Terminology -Respiration -Fermentation -High energy bonds -Terminal electron acceptors - fermentation exercise -The “Informal summary”

4. Terminology -Polar = charged -Non polar = uncharged -Reduced =losing “O” =acquiring “H atom” =acquiring electrons -Oxidized = acquiring “O atom” =losing “H atom” =losing electrons -Hydrogen ion “H + ” = proton

5. Terminology -Metabolism: sum of total reaction that occur in a cell and it consist of two types of processes 1- Catabolism:complex molecules are broken down into simpler molecules with the release of energy and reducing power (electrons). 2- Anabolism:Synthesis of complex molecules from simpler ones (building blocks) to form cell structures and macromolecules, this requires energy and often reducing power.

6. Respiration -it is defined as oxidation of a source of energy by removal of electrons and donation to an inorganic terminal electron acceptor. -the terminal electron acceptor is “oxygen”, so it has to happen in aerobic conditions.

7. Fermentation -it is defined as an energy yielding process whereby organic molecules serve as both electron donors and electron accepters. -it occur when there is no source for oxygen or when the cell or organism evolved to live in an anaerobic conditions -some anaerobic conditions include deep levels of the oceans, human and animal intestinal tracts or air-proof flask

8. Who does what -bacteria can either live in aerobic environment, anaerobic environment or both (facultative anaerobic). -yeast (baker yeast or Saccharomyces cerevisiae) is a facultative anaerobic organism. -human and animal cells generate energy by respiration (human and animal skeletal muscle cells can generate energy by fermentation). -plant cells generate energy by respiration (when oxygen is liberated from plants)

9. Fermentation versus respiration A-where energy and reducing power are stored -Energy carrier -These are intermediate "high energy" carriers that store this energy until the cell is ready to use it. -Two main types 1- Adenosine TriPhosphate (ATP) carrier of chemical energy in the form of high energy phosphate bonds

10. Fermentation versus respiration 2-Nicotinamide Adenine Dinucleotide (NAD + ) is a carrier of hydrogen and electrons and is involved in many oxidation-reduction reactions in the cell NAD+2e-+H + NADH 2e + H +

11. Fermentation versus respiration B- Do they have a common pathway -glycolysis or Embden-Meyerhoff-Parnas pathway (EMP) is a common pathway. -it occur in the cytosol of the cell 2ADP+2Pi 2ATP Glucose------------------->2 pyrovate 2NAD + +4e-+2H + 2NADH

12. Fermentation versus respiration C- what is the difference -Basically, how the limited amount of NDA is Regenerated and whether pyruvate molecules undergo further catabolism. -in fermentation, the electrons are passed to pyruvate with the formation of end products that is the excreted outside the cell. Yeast cell also Co 2 is released

13. Fermentation versus respiration Human and animal skeletal muscle cell

14. Fermentation versus respiration -in respiration The reaction continues, where the pyruvate molecules go into the citric acid cycle or Krebs cycle yielding more ATP, NADH, and FADH. -this occur in the matrix of mitochondria in eukaryotes or in the cytosol in bacteria. -the reduced molecules passes their electrons to O 2 that serve as terminal electron acceptor. This process is termed electron transport chain and occur at the level of mitochondrial membrane in eukaryotes or cell membrane in bacteria.

15. Fermentation versus respiration

17. -NADH get oxidized and the total process end with the production of---Co2 + H2O. -However, the electron transport chain result in proton gradient outside the membrane, this gradient is used to generate more ATP molecules using the protonmotive force

18. Fermentation versus respiration So, fermentation generate 2 ATP molecules, while Respiration generate 36 ATP molecules

19. I got the picture -start reading at the last paragraph of page 29. -Part B, add deionized water up to 100ml

20. The informal summary -it worth 18 points. It is due next week in lab. -It is distributed as follow 1-abstract--- 6 points 2-introduction---3 points 3-experimental procedures--- 2 point 4-results----2 points 5-discussion--- 4 points 6-references---1 -it is a rehearsal for a formal one.