Respiration Flashcards
What are the 4 steps in aerobic respiration
Glycolysis
Link Reaction
Krebs Cycle
Oxidative Phosphorylation
(Glycolysis & Krebs Cycle via SLP)
(34 from OP, 4 from SLP)
Why is glucose not used directly & ATP used as energy sources instead?
- Smaller amt of energy
released, controlled release & will not cause drastic increase in temp of cell - ATP is like a rechargable battery, can be readily regenerated by mitochondria ADP & Pi
30.6Kj/mol
What are the processes in Glycolysis
Occurs in CYTOSOL
1. Phosphorylation of hexose
2. Splitting of 6C sugar biphosphate
3. Oxidation/Dehydrogenation of triose phosphate
4. SLP of 3C sugar biphosphate
Describe Glycolysis
OCCURS in cytosol (by glycolytic enzymes) in 4 steps
1. Phosphorylation of hexose
- Glucose phosphorylated by 1 ATP -> glucose 6 phosphate, isomerised to fructose 6 phosphate -> Further phosphorylated by another ATP to 1,6 fructose bisphosphate.
- Lysis/splitting of 6C sugar bisphosphate
Thru splitting, fructose 1,6 bisphosphate is split into 2 molecules of triose phosphate
- Oxidation of glyceraldehyde-3-phosphate
NAD+ oxidises triose phosphate/glyceraldehyde 3 phosphate -> 1,3 biphosphoglycerate (generates 2NADH)
- Substrate level phosphorylation
By SLP of 2 moleq of 1,3 bisphosphate to pyruvate generates 4 ATP (net 2)
2 ATP &
2 NADH per glucose moleq
Link Reaction
OCCURS IN MITOCHONDRIAL MATRIX
Oxidative decarboxylation of 2 moleq of pyruvate by NAD+ to form 2 moleq of acetyl-coA (Produces 2 NADH & 2CO2 byproduct)
2NADH per glucose moleq
Krebs Cycle intermediates
Citrate
Isocitrate
α-ketoglutarate
Succinyl CoA
Succinate
Fumarate
Malate
Oxaloacetate
Describe Krebs Cycle
OCCURS IN MITOCHONDRIAL MATRIX
1. 2C acetyl coA taken up by oxaloacetate
-> 6C CITRATE
2. 6C citrate isomerised to ISOCITRATE
- Isocitrate undergoes OXIDATIVE DECARBOXYLATION to form α ketoglutarate (CO2 removed, NAD reduced to NADH)
- α ketoglutarate (further oxidative decarboxylation) 4C SUCCINYL COA producing NADH & CO2
- Succinyl CoA converted to 4C SUCCINATE (ATP produced)
- Succinate oxidised by coenzyme FAD to 4C FUMARATE (forms FADH2)
- Fumarate convereted to MALATE (addition of H2O)
- Malate oxidised to OXALOACETATE by NAD, forms NADH (releases 2 H)
For 1 glucose & 2 cycles (2 pyruvate->2acetyl coa)
6 NADH
2 FADH2
2 ATP
4 CO2
2 oxaloacetate
Describe ETC (in inner mitchondrial membrane)
located in INNER MITOCHONDRIAL MEMBRANE
NADH & FADH2 are e- carriers that donate e- to ETC in inner mitochondrial membrane
- e- carriers are of progressively lower energy levels transferred from NADH & FADH2 to series of carriers then O2 (FEA, reduced to H2O) thru redox rxns
-> Energy released used by proton pump to actively transport H+ from mitochondrial matrix into IMS
Describe ATP synthase & oxidative phosphorylation (coupled w ETC -> chemiosis)
(Contains transmembrane hydrophilic channel -> diffusion of H+ down conc. gradient from IMS back into mitochondrial matrix)
OP: By a series of redox rxns, e- transferred from NADH/FADH2 to e- carriers of progressively lower energy level, finally to O2 forming water
- Energy released from passage of e- is used for active transport of H+ from matrix into IMS via active transport in proton pumps
-> Creates proton gradient across IMS, When H+ diffuse back (chemiosmosis) thru ATP synthase down conc. gradient via Facilitated diffusion, energy released to generate ATP from ADP & Pi)
Describe anaerobic respiration
(Only glycolysis -> 2 pyruvate & 2 ATP per glucose moleq)
KC & OP cannot operate in absence of O2 (no final e- acceptor) -> ETC ceases
GLYCOLYSIS proceeds but only SLP only 4/38 (OP 34/38 cannot occur)
NAD & FAD not regenerated from OP, KC & LR cannot proceed (NADH & FADH2 remain in reduced state)
Glycolysis only produces net 2 ATP
Describe anaerobic resp & production of ethanol
From glycolysis: 2 pyruvate + 2H2O + 2ATP & 2 NADH
Pyruvate is first decarboxylated to ethanal with release of CO2
NADH from glycolysis donates 2H atoms to ethanl & its reduced to ethanol by alcohol dehydrogenase, NAD regenerated
(Hence regenerating NAD for glycolysis to continue with ATP production)
Describe anaerobic resp & Production of lactic acid
