18.6 - Respiratory Substrates

Question 1

What is a respiratory substrate?

Answer 1

Molecule that can be broken down in respiration to release energy

ENEGRY VALUE: carbs>protein>fats

• carbohydrates - converted to glucose
• fats - fatty acids from fats broken down to acetyl (2-carbon) and enters at the Krebs cycle via coenzyme A.
  
  • fatty acids have many carbons so there are many acetyl groups, so more NAD is reduced and the FADH2 & NADH produce many ATP - fats are energy rich
• proteins - converted to amino acids, then deaminated.
  
  • The remaining residues are organic acids that enter the Krebs cycle as intermediates

Question 2

How do you calculate RQ and what are common RQ values?

Answer 2

RQ = CO₂ produced/oxygen used

Carbohydrate = 1.0

Protein - 0.9

Lipid/fat = 0.7