Cellular Respiration

  1. Cellular Respiration
    Overview of eukaryotic respiration
    C6H12O6 + 6O2 -> 6CO2 + 6H2O + E(ATP)
    C6H12O6 oxidized to 6CO2; 6O2 reduced to 6H2O
    In cytosol -> mitochondria
    Function: oxidize C6H12O6 to ATP (move e-/H+)
    e- source is C6H12O6, polar, gets through membrane by transport protein, O2 drives process, O2 pulls on e-
    NAD+ + 2e- + H+ = NADH
    FAD + 2e- + 2H+ = FADH2 (NADH and FADH2 are e- carriers, stored E to make ATP: has spring-loaded bond)
    Glycolysis
    C6H12O6 enters through fac. Diffusion
    E investment phase: 2 ATP (endergonic), + delta G (nonspontaneous), 1 C6H12O6 -> 2 G3P
    Phosphorylation ATP couples to reactions
    E payoff phase (exergonic)
  • delta G, 2 G3P -> 2 pyruvate/2 NADH/4 ATP
    Substrate-level phosphorylation: phosphate groups removed/transferred to ADP -> new ATP
    Pyruvate oxidation
    Outer mitochondrial membrane: diffusion through small pores
    Inner mitochondrial membrane: carrier protein
    Pyruvate -> acetyl Coenzyme A (no ATP required)
    Catalyzed by pyruvate dehydrogenase (removed H+, builds NADH)
    Citric acid cycle
    1 C6H12O6 has 2 turns (1 per acetyl coA)
    Oxaloacetate (4C) waits in matrix; Enzyme joins oxaloacetate/2C: Acetyl group -> citrate
    Cycle tears apart citrate -> e- (H) in C6H12O6 -> e- acceptors NAD+/FAD
    NADH/FADH2; C6H12O6 oxidized -> CO2 -> 1 ATP made
    Oxidative phosphorylation
    Converts E in NADH/FADH2 -> ATP
    C lost as CO2, 4 ATP produced (so far)
    E from C6H12O6 -> excited e- in NADH/FADH2 (e- carriers)

ATP from ETC/chemiosmosis
First break up NADH/FADH2
Pull e- off with O2 help then e- E -> pulls H+ off carriers/dam it up
Set up for ATP synthesis
ETC move e- from high to low excitement
Made of proteins 1-4 (e- carriers)
I/II hydrolyze e- carriers
III/IV pump H+ into intermembrane space
IV passes e- -> O2 -> forms H2O with addition of 2H+
E- transfer in ETC -> proteins pump H+ to intermembrane space -> make H+ gradient
ETC makes no ATP, H2O produced, is final acceptor of e- in process, ATP (high PE) made through ATP synthase
Chemiosmosis: uses H+ gradient for cellular work
ATP synthase: mol. Mill -> inner membrane enzyme
ETC -> H+ gradient (H+ is ion)
H+ diffuse back to matrix through ATP synthase (rotates)
Phosphorylation (ADP + Pi -> ATP)

Why
Where
What enters
What is produced
Glycolysis
investment/payoff for pyruvate/ATP
cytosol
C6H12O6 by fac. Diffusion (mammals) GLUT1
2 G3P, 4 ATP, 2 NADH
Pyruvate oxidation
Pyruvate -> acetyl coA
mitochondria
2 pyruvate, 8 NAD+, 2 FAD, 2 ADP
6 CO2 (exhaled), 8 NADH (ETC), 2 FADH2 (ETC), 2 ATP (substrate level phosphorylation)
Citric acid cycle
Break acetyl coA down as efficiently as possible -> build e- carriers to give to ETC
Mitochondrial matrix
2 acetyl coA

Oxidative phosphorylation
Make ATP from excited e- of carriers
Cristae (inner)
10 NADH, 2 FADH2, 6 O2
28 ATP

CR
Photosynthesis
Equation
C6H12O6 + 6O2 -> 6H2O + 6CO2 + ATP
Light + 6CO2 + 6 H2O -> C6H12O6 + 6O2
where
Mitochondria
Chloroplast
energy
Exergonic
Endergonic
Inner membrane
cristae
thylakoid
function
Get ATP from food
Make food
Proton gradient
Cristae -> matrix (out to in)
Thylakoid to stroma (in to out)
E- source
C6H12O6, NADH, FADH2
Oxidize H2O @ PSII
Final e-
O2
NADP+
ATP synthase
Yes
Yes