Respiratory Substrates 18.6

Question 1

How are triglycerides used as respiratory substrates?

Answer 1

Glycerol is converted into pyruvate before undergoing oxidative decarboxylation and produces an acetyl group which then combines with coenzyme A to make acetyl coA. This is known as beta-oxidation.

Question 2

How many ATP molecules can a triglyceride produce?

Answer 2

One triglyceride can form 50 acetyl CoA molecules so can make 500 ATP molecules. They become more reduced so more NADH is produced for oxidative phosphorylation.

Question 3

Why is a protein not normally used for respiration?

Answer 3

it has to be hydrolysed into amino acids and deaminated before it can become pyruvate. This takes up a lot of energy so isn’t a preferred respiratory substrate

Question 4

Order which respiratory subs produce the most energy

Answer 4

Lipids produce twice as much as carbs
Alcohol produces more than carbs but less than lipids
Protein is equivalent

Question 5

What is the RQ?

Answer 5

The respiratory quotient which calculates which respiratory substrate is being used at that time

Question 6

How do you calculate the RQ?

Answer 6

RQ = Co2 produce / O2 taken up

Question 7

What are the RQs of respiratory substrates?

Answer 7

Carbohydrates = 1
Lipids = 0.7
Protein = 0.9