5.18.6) Respiratory substrates

Key information required for this part of the Respiration topic for OCR A Level Biology

What are the reactions required to convert a triglyceride into products that can be used in respiration reactions

Triglyceride is hydrolysed to fatty acids and glycerol. The fatty acids are converted to 2C compounds, which undergo beta oxidation to form acetyl coenzyme A. Glycerol is either converted to pyruvate or phosphorylated to form triose phosphate.

What are the reactions required to convert a protein into products which can be used in respiration reactions

Proteins are hydrolysed to form amino acids. These undergo deamination to remove NH2 in the liver (converted to urea and excreted). The product is converted into 3-5C compounds. 3C compounds are converted to pyruvate, 4-5C compounds are converted to keto acids and used in the Krebs cycle.

What is the equation for the respiratory quotient, RQ

Volume of CO2 produced / volume of O2 consumed

What is the RQ of carbohydrates, proteins and lipids

1.0, 0.9, 0.7

Why might the RQ increase above 1

Anaerobic respiration is taking place

What does a respirometer measure, which direction does the coloured fluid move and what can be used to absorb the carbon dioxide

Volume of oxygen uptake; towards the container; soda lime, metal hydroxide solution