Respiration Flashcards
(34 cards)
Where do most of the reactions take place in respiration
mitochondria
Name the 3 coenzymes used in respiration
NAD
Coenzyme A
FAD
NAD + FAD do what
transfer hydrogen, reduce/oxidise
Coenzyme A does what
transfers acetate
3 things the matrix contains
- enzymes
- FAD + NAD
- All other reactants needed for link reaction and Krebs cycle
Name the 4 stages of Aerobic Respiration
- Glycolysis
- Link Reaction
- Krebs cycle
- Oxidative Phosphorylation
Where does Glycolysis occur and why
Cytoplasm
glucose cant cross outer mitochondrial membrane
summarise glycolysis in 2 steps
- phosphorylation of glucose to hexose Biphosphate by 2x ATP. This splits into 2x Triose phosphate
- Oxidation of 2x TP to 2x pyruvate, by 2x NAD. Creates 4x ATP
State the products of Glycolysis and where they go
- 2x NADH, to oxidative phosphorylation
- 2x Pyruvate, to link reaction
- 2x ATP(as 2 are used up in Glycolysis), used for energy
summarise the link reaction in 2 steps
- pyruvate actively transported into matrix where its decarboxylated (loses 1C) to form CO2. Then oxidised by 2x NAD to form 2x Acetate(catalysed by pyruvate dehydrogenase).
- Acetate combines with CoA to form Acetyl CoA. (No ATP produced)
State the products of the Link Reaction and where they go
- 2x NADH, oxidative phosphorylation
- 2x Acetyl CoA, Krebs cycle
- 2x CO2, released as waste product
Where does the link reaction occur
Mitochondrial matrix
State the equation for the Link reaction
2Pyruvate + 2NAD + 2CoA -> 2CO2 + 2NADH + 2AcetylCoA
Where does the Krebs cycle occur
Mitochondrial matrix
summarise the Krebs cycle in 3 steps
- 2-C Acetyl CoA + 4-C Oxaloacetate forms 6-C Citrate, catalysed by Citrate Synthase. CoA reused in link reaction
- Citrate is decarboxylated then dehydrogenated producing 5-C molecule. Produces CO2 + NADH
- 5-C molecule converted to Oxaloacetate by decarboxylation -> CO2, then dehydrogenated by 2xNAD + FAD -> 2xNADH + 1xFADH. ATP produced via substrate level phosphorylation.
State the products of the Krebs cycle and where they go
- 3x NADH, to oxidative phosphorylation
- 2x CO2, released as waste product
- 1x ATP, used for energy
- 1x FADH, to oxidative phosphorylation
- 1x CoA, back to link reaction
- 1x Oxaloacetate, reused in Krebs cycle
Whats substrate level phosphorylation
When a phosphate group is directly transferred from one molecule to another.
What is the point of the previous stages to oxidative phosphorylation
To make NADH + FADH
summarise the oxidative phosphorylation in 5 steps
- NADH + FADH reoxidised, releases H atoms. H atom splits into protons and electrons. Proton enters solution in matrix.
- Electrons pass along ETC(made up of 3 carrier proteins with iron cores) located in inner membrane. Membrane folded into cristae to increase S/A.
- Electron loses energy at each carrier, energy used to pump protons from matrix to inter-membrane space. Creates electrochemical gradient.
- Protons diffuse down electrochemical gradient back into matrix via ATP synthase. This movement of protons drives synthesis of ATP from ADP+Pi. (Chemiosmosis)
- In matrix, at end of ETC, protons + electrons + oxygen (from blood) combine to form H2O. Oxygen=final electron acceptor.
What is referred to as the final electron acceptor in oxidative phosphorylation
and what is the equation for this
Oxygen
4H+ + 4e- + O2 -> 2H2O
Stage of respiration Net gain of ATP per glucose
Glycolysis ?
Link reaction ?
Krebs cycle ?
Oxidative phosphorylation ?
Total ?
2 0 2 28 32 Actual yield is 30 or lower as some used to transport pyruvate into mitochondria, some protons may leak out of outer membrane
What is Anaerobic respiration
process where energy us released from glucose without oxygen
what organism carry out lactate fermentation
mammals
some bacteria
describe how lactate fermentation works
- Pyruvate accepts hydrogen atom from NADH, catalysed by lactate dehydrogenase
- pyruvate reduced to lactate, NADH is reoxidised
- reoxidised NAD can continue glycolysis
