Respiratory substrates

Different respiratory substrates

- Glucose

- Triglycerides

- Lipids

- Proteins

Compare the amount of energy carbs, lipids, alcohols and proteins store and release

Lipids \> Alcohol \> Carbs ≈ Proteins

How does triglycerides enter the Krebs cycle?

- They are hydrolysed to fatty acids and glycerol

- Glycerol is converted to pyruvate b4 oxidative deCO2, making a acetyl group that's picked up by CoA

- Fatty acids enter by acetyl CoA

How how do proteins enter the respiratory pathway?

- Hydrolysed to amino acids

- AA deaminated (remove amine group)

- Enter using pyruvate, needs energy

How different biological molecules enter the respiratory pathway

What is the respiratory quotient?

RQ = volume of CO2 produced / volume of O2 consumed
- Using a respirometer

How many oxygen molecules does it take to respire one molecule of glucose?

6
- 6 CO2 and 6H2O is also made
- 6/6 = 1

Why do lipids produce so much ATP in respiration?

Higher proportion of C-H bonds
- More oxygen is needed to break them down
- Less CO2 is released

What are the RQ values for carbs, lipids and proteins?

Carbs - 1

Proteins - 0.9

Lipids - 0.7

What does the RQ value tell us?

The type of substrate being used for respiration at that point

What is the normal RQ value and what does it show us?

- 0.8-0.9

- Carbs and lipids are mainly being used as respiratory substrates