EN: Aerobic Respiration Flashcards
Link reaction.
Stage after glycolysis which converts pyruvate to acetyl coenzyme A.
Stage after glycolysis which converts pyruvate to acetyl coenzyme A.
Link reaction.
Where does the link reaction occur?
In the mitochondrial matrix.
Pyruvate is decarboxylated - what does this mean?
One carbon atom is removed from pyruvate in the form of CO2.
Briefly describe the stages of the link reaction:
- Pyruvate is decarboxylated - carbon is removed in form of CO2.
- Pyruvate is oxidised to form acetate and NAD is reduced to form reduced NAD.
- Acetate is combined with coenzyme A (CoA) to form acetyl coenzyme A.
No ATP is produced.
Is ATP produced in the Link reaction?
No, none is produced.
Draw a diagram to represent the link reaction:
Briefly describe the stages of aerobic respiration:
- Glycolysis
- Link reaction
- Krebs cycle
- Oxidative phosphorylation
How many pyruvate molecules are made for every glucose molecule that enters glycolysis?
What does this mean?
2
Means for each glucose molecule:
- 2 molecules of acetyl coenzyme A go into the Krebs cycle.
- 2 CO2 molecules are released as waste products.
- 2 molecules of reduced NAD are formed and go to oxidative phosphorylation.
Where does the Krebs cycle occur?
Mitochondrial matrix
What does the Krebs cycle produce?
Reduced coenzymes and ATP
Briefly, what does the Krebs cycle involve?
A series of oxidation-reduction reactions
How many times does the Krebs cycle happen for pyruvate molecules?
How many times does it happen for glucose molecules?
Pyruvate = once
Glucose = twice
What happens in the first part of the Krebs cycle?
- Acetyl CoA from link reaction combines with 4C molecule (oxaloacetate) to form a 6C molecule (citrate).
- Coenzyme A goes back to link reaction.
What happens in the second part of the Krebs cycle?
- 6C citrate molecule is converted to 5C molecule.
- Decarboxylation occurs - CO2 removed.
- Dehydrogenation occurs.
- Hydrogen is used to produce reduced NAD from NAD.
What happens in the third stage of the Krebs cycle?
- 5C molecule is converted to 4C.
- Decarboxylation and dehydrogenation - produce 1 molecule of reduced FAD and 2 reduced NAD.
- ATP produced by direct transfer of a phosphate group from an intermediate compound to ADP - substrate-level phosphorylation.
- Citrate converts to oxaloacete.
Substrate-level phosphorylation
A phosphate group is directly transferred from one molecule to another.
A phosphate group is directly transferred from one molecule to another.
Substrate-level phosphorylation
Draw a diagram to represent the Krebs cycle:
What are all the products of one Krebs cycle?
Where does each go?
1 coenzyme A = reused in the next link reaction.
Oxaloacetate = regenerated for use in the next Krebs cycle.
2CO2 = released as waste product.
1 ATP = used for energy.
3 reduced NAD = oxidative phosphorylation.
1 reduced FAD = oxidative phosphorylation.
Relavatively speaking, how much ATP does oxidative phosphorylation produce?
Lots.
Oxidative phosphorylation.
The process where the energy carried by electrons, from reduced coenzymes (FAD and NAD), is used to make ATP.
The process where the energy carried by electrons, from reduced coenzymes (FAD and NAD), is used to make ATP.
Oxidative phosphorylation.
What is the point of glycolysis, the Link reaction and the Krebs cycle?
To make reduced NAD and reduced FAD for the final stage - oxidative phosphorylation.
Describe the process of oxidative phosphorylation.
- H atoms are released from reduced NAD and FAD when they are oxidised.
- H atom splits to H+ and e-
- e- move down electron transport chain, losing energy at each carrier.
- Energy is used to pump protons from mitochondrial matrix to intermembrane space.
- Concentration of H+ is higher in intermembrane space than in mitochondrial matrix - electrochemical graident forms.
- Protons move back to matrix through ATP synthase - drives the synthesis of ATP from ADP and Pi - chemiosmosis.
- At the end of ETC, protons, electrons and O2 combine to form water - oxygen is the terminal electron acceptor.
Why do protons diffuse through ATP synthase?
It is the only part of the inner mitochondiral membrane permeable to them.
What happens to the regenrated coenzymes (FAD and NAD) made in oxidative phosphorylation?
They are reused in the Krebs cycle.
In oxidative phosphorylation, where do protons move to and from?
From mitochondrial matrix to the intermembrane space and back again.
How many ATP molecules are made from each molecule of reduced NAD?
How many ATP molecules are made from each molecule of reduced FAD?
Reduced NAD = 2.5 ATP
Reduced FAD = 1.5 ATP
Draw a table to demonstrate the total amount of ATP produced in aerobic respiration:
What can ATP production be affected by?
Mitochondrial diseases.
How can mitochondrial diseases affect ATP production?
- Affect mitondria - can affect how proteins involved inn oxidative phosphorylation or Krebs cycle function, so reducing ATP production.
- May cause anaerobic respiration to increase to make up for ATP shortage.
- Lots of lactate is produced - can cause fatigue and weakness.
- Lactate can also diffuse into bloodstream, leading to high lactate concentrations.
