Day 40

Question 1

Oxidation

Answer 1

Gives up e-

Dehydrogenation gives up H+

Question 2

Reduction

Answer 2

Accepts e-

Hydrogenation accepts H+

Question 3

Biological Redox Reactions

Answer 3

• usually involves 2e-/2H+ in the cell

- catalyzed by dehyrogenases

Question 4

Oxidation/Reducation NAD+/NADH and FAD/FADH2

Answer 4

1) NAD/NADH
- reversible reduction occurs with a hydride ion (proton with two electrons)
- NAD+ can only accept 2 electrons as a time
2) FAD/FADH2
- FAD can accept 1 e- and be a stable radical/semiquinone
- accept 2e- and be fully reduced
- adds by hydrogen atom (one H+ one e-) at a time
- humans don’t synthesize favin rings, get from riboflavin (B2)

Question 5

Standard Reduction Potentials

Answer 5

• relative to hydrogen half-half reaction of reduction where pH=0, 25C, 1atm
• large positive value means high affinity for electrons and is strong electron acceptor
• electrons spontaneously flow from low to high reduction potentials
• these numbers do not show when proteins are present
• dG = -nFdE

Question 6

The Mitochondrion

Answer 6

• all CAC enzymes, fatty acid oxidation enzymes, and proteins for ETC and oxidative phosphorylation
• Outer and inner membranes. Inside has invaginations/cristae where the ETC/OP proteins are
• between membranes is innmembrane space and inside the inner membrane is the matrix

Question 7

Mitocondrial Membranes

Answer 7

• Outer Membrane- porins that allow free diffusion of molecules < 10kD which makes cytosol and inner membrane space equivalent in regards to ion and metabolite concentrations
• Inner membrane- Only freely permiable to O2, H2O, and CO2 so it has a lot of transporters especially for molecules like ATP, ADP, pyruvate, Ca2+, and phosphate
• Makes ion gradient possible!

Question 8

The Glycerophosphate Shuttle

Answer 8

• NADH from glycolysis needs to get into mitocondria
• Only NADH’s e-‘s are “shuttled”
  1) Glycerophosphate shuttle oxidizes NADH using DHAP to create 3-phosphoglycerol
  2) e-‘s from 3-phosphoglycerol are transferred to FAD-containing protein in the inner membrane (flawoprotein dehydrogenase)
• ***why NADH give 2.5 atp instead of 3. Need DHAP for shuttle.

Question 9

The ADP-ATP Translocator

Answer 9

• ATP from oxidative phosphylation is needed in cytosol
• ADP-ATP translocator is a dimer of identical 30kD units with one binding site for ADP and ATP to fight over
• Conformations are either 1) active site facing inside of mitocondria or 2) facing outwards but needs to bind ligand to change conformations
• one ADP for one ATP gives net export of one negative charge but this is because of the membrane potential difference where the outside is positive due to the proton gradient