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
Today • Terminology • Respiration • Fermentation • High energy bonds • Terminal electron acceptors • fermentation exercise • The “Informal summary”
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
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.
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.
Fermentation • it is defined asan 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
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)
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
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+
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
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 Co2 is released
Fermentation versus respiration Human and animal skeletal muscle cell
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 O2 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.
Fermentation versus respiration -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
Fermentation versus respiration So, fermentation generate 2ATP molecules, while Respiration generate 36ATP molecules
I got the picture -start reading at the last paragraph of page 29. -Part B, add deionized water up to 100ml
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.