Component 1.3 - Aerobic Respiration Flashcards
Overview of respiration
- Metabolic pathway as it is a series of enzyme catalysed reactions
- The reactions are catabolic
- Break down of energy rich molecules containing high energy C-H, C-C, C-OH bonds to form low energy bonds (difference is released and used to attach P to ADP)
Definition of aerobic respiration
The release of large amounts of energy made available as ATP, from the breakdown of molecules, with oxygen as the terminal electron acceptor.
Where does glycolysis occur?
In the cytoplasm
Why does glycolysis occur in the cytoplasm?
Because glucose cannot pass through the mitochondrial membrane
Why is it important that glucose is phosphorylated in glycolysis?
- It will be more reactive so less activation energy for enzyme controlled reactions
- Polar and therefore less likely to diffuse out of the cell.
What are the steps of glycolysis?
1) Glucose is phosphorylated by two molecules of ATP
2) This produces hexose biphosphate (6C)
3) Hexose biphosphate splits into two molecules of triose phosphate (3C)
4) The two triose phosphate molecules are dehydrogenated
5) This makes two molecules of reduced NAD and oxidises the molecules to 2 pyruvate
6) This synthesis produces 2x2(4) molecules of ATP by substrate-level phosphorylation
What is the net gain of ATP in glycolysis per molecules of glucose?
2 molecules of ATP are used,
4 molecules of ATP are made by substrate level phosphorylation
6 are made by oxidative phosphorylation.
Net gain of 8 molecules of ATP
Describe substrate-level phosphorylation in glycolysis
The phosphate from the triose phosphate converts ADP to ATP without the involvement of an electron transport chain.
How many molecules of ATP can one molecule of reduced NAD make?
3
Overall reaction of glycolysis
Glucose + 2NAD(oxidised) + 2ADP + 2Pi -> 2 pyruvates + 2NAD(reduced) + 2ATP + heat
Where does the link reaction occur?
The mitochondrial matrix
What happens in the link reaction?
1) Pyruvate is dehydrogenated
2) This forms one molecule of reduced NAD
3) Pyruvate is also decarboxylated (forming CO2)
4) This leaves acetate (2C) and coenzyme A (coA) which combine to form acetyl coenzyme A
Describe the Krebs cycle
1) Acetate from Acetyl coenzyme A combines with 4C acid to form 6C acid and coA is regenerated
2) 6C acid is dehydrogenated and decarboxylated, making reduced NAD, co2 and 5C acid.
3) 5C is dehydrogenated and decarboxylated, making reduced NAD and regenerated 4C. One molecule of ATP is made my substrate level phosphorylation.
4) 4C is dehydrogenated twice forming reduced NAD and reduced FAD
4) 4C can combine with AcCoA to repeat the cycle
What is the function of the Krebs cycle?
Liberating energy from carbon bonds via reduced intermediates to provide ATP and NAD, with the release of carbon dioxide.
What else is fed into the Krebs cycle at 3 different points?
H2O
