Metabolism Flashcards
How many stages of fuel oxidation are there?
3
What occurs in the first stage of fuel oxidation?
Hydrogens and electrons are ripped out of the fuel and the fuel breaks up into two-carbon acetate. This is carried on Acetyl-CoA. (Card 1)
What occurs in the second stage of fuel oxidation?
Acetyl CoA is further oxidised in the Krebs cycle by removing more H/e until carbon atoms in acetate converted to carbon dioxide. (Card 1)
Is the second stage of fuel oxidation aerobic or anaerobic?
anaerobic - no oxygen is used in this process.
What are the H/e- strippers?
Nicotinamide adenine dinucleotide (NAD)
Flavin Adenine dinucleotide (FAD)
What is the role of NAD in H/e- stripping/carrying?
Oxidises -CH2-CHOH- to become NADH.
What is the role of FAD in H/e- stripping/carrying?
Oxidises -CH2CH2- to -CH=CH- to become FADH2.
What are the limits of FAD and NAD?
Once they have stripped H/e- from the fuel they carry that so they can’t do any more stripping. They are also in limited supply.
What has occurred at the end of stage 2 fuel oxidation?
Oxidised the fuels but not much ATP made yet.
What happens in stage 3 of fuel oxidation? How does this occur?
The energy of h/e- are captured. The reaction between hydrogen and oxygen liberates a lot of energy which can be captured as chemical/potential energy. The formation of a proton gradient works like a battery. (Card 2)
How can ATP be made with the H+ gradient formed in stage 3?
Proteins flow under pressure through the channel in the inner mitochondrial membrane. As they come in they cause another protein to rotate which interacts with the subunits of the ATP synthase to generate ATP from ADP and phosphate.
Where does the ATP go after it is formed after stage 3?
The cytoplasm to do work.
ADP is in excess or short supply?
Short supply.
What is required for ADP synthesis?
ATP breakdown - but it is very stable and so won’t breakdown unless the reactions it drives are constant - if cells don’t use ATP they cant make it.
The inner mitochondrial membrane is impermeable to ______. What does this mean?
Protons. Protons can only come through if it is through the ATP synthase and so only if ATP is being made.
Proton pumps won’t work unless the proton gradient is ____? Why?
Very high-pressure systems won’t allow it.
What will happen if no protons are pumped across the membrane?
There will be no H/e movement down the electron transport chain - no energy.
What are the 3 fuel sources and their oxidation pathways?
Fatty acids - beta-oxidation.
Glucose - glycose oxidation
Proteins - many pathways: channel to pyruvate, acetyl-CoA or Krebs cycle.
What are the features of fatty acids?
(Card 3)
What are the features of glucose?
(Card 3)
What are the features of proteins?
(Card 3)
Describe the process of beta-oxidation.
(Card 4)
Describe the process of glucose oxidation.
(Card 4)
Draw and be able to explain what happens in catabolism for Fatty acids and glucose.
(Card 5)
What is meant by coupling in fuel oxidation?
The rate of ATP synthesis is exactly matched to the rate of ATP use. The cells cant do work without burning fuel and catabolism is controlled by demand.
What is the rate of ATP turnover?
Massive. Store 1g/kg body weight turnover 1kg/kg body weight.
