18.6 Respiratory Substrates

Question 1

How do you calculate RQ value

Answer 1

CO2 produced / O2 consumed

Question 2

What is the RQ value of Carbohydrates

Answer 2

1.0

Question 3

What is the RQ value of Lipids

Answer 3

0.7

Question 4

What is the RQ value of proteins

Answer 4

0.9

Question 5

Why is the RQ value of lipids less than carbohydrates

Answer 5

-lipids contain a greater proportion of carbon-hydrogen bonds than carbohydrates so produce more ATP
-greater number of C-H bonds, more oxygen is required to break the bonds and release less CO2

Question 6

How are triglycerides used for respiration

Answer 6

1. Triglycerides are hydrolysed into glycerol and 3 fatty acids
2. Glycerol is converted into pyruvate
3. The fatty acids can lead to the formation of as many as 50 acetyl coenzyme A molecules through Beta oxidation, which can synthesise up to about 500 ATP molecules

Question 7

How are proteins used for respiration

Answer 7

1. proteins are hydrolysed into amino acids
2. amino acids are deaminated to pyruvate

Question 8

Why do we typically avoid using proteins for repiration

Answer 8

1. Deamination required the use of ATP, so overall net ATP is reduced
2. Proteins make up enzymes, without enzymes muscle mass would be lost

Question 9

Which respiratory substrates release the most energy

Answer 9

-lipids store and release twice as much energy as carbohydrates
-alcohol contains more energy then carbohydrates but less than lipids
-proteins are roughly equal to carbohydrates

Question 10

What happens to the RQ value during anaerobic respiration

Answer 10

-rises above 1.0 but is not easy to measure