Different Respiratory Substrates

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What is a respiratory substrate?
An organic substance that is used to produce ATP in a cell by respiration.
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Why do lipids release more energy than carbohydrates and proteins?
Lipids contain fatty acids- these have lots of hydrogen atoms. So more H atoms go to NAD/FAD, more electrons are released and go down ETC and more ATP is made.
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How efficient is aerobic respiration?
Each glucose respired makes 32 ATP molecules. Each one releases 30.5kJ energy. Divided by lab result of 2870kJ/mol. Gives 34% efficiency.
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Why is there not 100% efficiency with aerobic respiration of glucose?
Some energy is released as heat during respiration- this is useful to endotherms as it helps with thermoregulation. Energy is also used to move molecules around in the cell, such as the pyruvate and ADP into the mitochondria.
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Describe how lipids are respired.
Triglycerides are hydrolysed by lipase into 3 fatty acids & glycerol. Glycerol can enter into glycolosis. The fatty acids can be combined with acetyl-co-A, then broken down & released into Krebs cycle. Lots of H atoms released, so lots of ATP made.
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Describe how proteins are respired.
If an organism undergoes fasting, starvation or excessive prolonged exercise, protein from muscle can be hydrolysed back into amino acids which can then be respired. Different a.a can enter respiration at different points.
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Other cards in this set

Card 2

Front

Why do lipids release more energy than carbohydrates and proteins?

Back

Lipids contain fatty acids- these have lots of hydrogen atoms. So more H atoms go to NAD/FAD, more electrons are released and go down ETC and more ATP is made.

Card 3

Front

How efficient is aerobic respiration?

Back

Preview of the front of card 3

Card 4

Front

Why is there not 100% efficiency with aerobic respiration of glucose?

Back

Preview of the front of card 4

Card 5

Front

Describe how lipids are respired.

Back

Preview of the front of card 5
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