Respiratory substrates

Question 1

What is a respiratory substrate

Answer 1

A biological molecule that can be broken down in respiration to release energy

Question 2

Describe the process of lipid breakdown

Answer 2

• Lipids are first hydrolysed for glycerol and fatty acids
• Glycerol is then phosphorylated to form a triose phosphate, which is entered into glycolysis
• The fatty acids are broken down into 2 carbon fragments, which are converted to acetyl coA, which is used in the krebs cycle. This is the beta oxidation pathway

Question 3

Describe how proteins are used as a respiratory substrate

Answer 3

• Proteins are first broken down into their constituent amino acids
• Amino acids sent to the liver for deamination where the amino groups are removed and converted to urea, leaving a keto acid
• The keto acid can be converted into pyruvate, acetyle coA or a krebs cycle intermediate