Metabolism 5

Question 1

How was the Krebs cycle discovered?

Answer 1

-found that adding carboxylic acids to pigeon muscle caused unusually large O2 uptake
-means each acid was acting catalytically
-observed that malonate inhibited respiration and malonate poisoned tissue accumulated succinate
-found it would always accumulate when malonate present no matter the acid - suggested a cycle

Question 2

How do you measure oxygen uptake using a Warburg Manometer?

Answer 2

-measure change in pressure caused by O2 uptake during respiration by a homogenised tissue sample
-CO2 absorbed by KOH soaked filter paper
-substrate reagents added in side flask + mixed by tipping

Question 3

What acts as a source of acetyl CoA?

Answer 3

Fatty acids

Question 4

Why are fats more reduced than sugars?

Answer 4

They generate more energy when oxidised

Question 5

What does lipase breakdown fats into and where are they transported to?

Answer 5

-fats breakdown into glycerol + fatty acids
-glycerol enters glycolysis due to conversion into DHAP
-fatty acids transported into mitochondria

Question 6

Describe fatty acid 𝛽 oxidation

Answer 6

-activated via linkage to coenzyme A + transported into mitochondria
-requires ATP –> AMP + PPi
-4 enzymes oxidise fatty acid-CoA 1 carbon unit at a time
-oxidations (-ΔG) coupled to generation of FADH2 + NADH (+ΔG)
-acetyl CoA enters Krebs cycle