Wk2 Metabolism

Question 1

What is metabolism?

Answer 1

• Chemical processes that occur within a living organism in order to maintain life
• Metabolic pathway starts with a specific metabolite and ends with a product through a chain of enzymatically catalysed reactions

Question 2

What is the full TCA cycle? (ENZYMES)

Answer 2

CoA + CITRATE SYNTHASE ==>

Citrate + ACONITASE - H2O ==>

cis-Aconitase + ACONITASE ==>

Isocitrate + ISOCITRATE DEHYDROGENASE - CO2 - NADH ==>

a-keto-glutarate + a-KETOGLUTARATE DEHYDROGENASE COMPLEX - CO2 - NADH ==>

Succinyl CoA + SUCCINYL COA SYNTHETASE - GTP ==>

Succinate + SUCCINATE DEHYDROGENASE - FADH2 ==>

Fumarate + FUMERASE + H2O ==>

Malate + MALATE DEHYDROGENASE - NADH ==>

Oxaloacetate + CoA etc… (start again)

Question 3

What is the simplified TCA cycle?

Answer 3

Acetyl CoA (C2) ==>
C6 - NADH - CO2 ==>
C5 - NADH - CO2 ==>
C4 - GTP - FADH2 - NADH ==>
C4 (start again)

Question 4

What is a catabolic pathway?

Answer 4

Break down complex molecules into simple molecules and release energy

Question 5

What is an anabolic pathway?

Answer 5

Build complex molecules from simple molecules and require energy usually in the form of ATP

Question 6

What is glucose metabolism?

Answer 6

Series of reactions involving several metabolic pathways. In eukaryotic cells every reaction occurs at a special location.

Question 7

What is the overall process of metabolism?

Answer 7

Glucose + fatty acids ==>
Acetyl CoA ==>
TCA cycle ==>
NADH ==>
ATP

Question 8

What reactions are cytosolic?

Answer 8

• Glycolysis
• PPP
• Fatty acid synthesis

Question 9

Where are energy metabolism related pathways (TCA cycle, b-oxidation, respiratory chain) located?

Answer 9

Mitochondria

Question 10

Where are enzymes for the TCA cycle located?

Answer 10

Mitochondrial matrix
- Except succinate dehydrogenase which is linked to respiratory chain in the inner membrane
Other locations include peroxisomes, nucleus etc.

Question 11

What are different reaction types?

Answer 11

• Hydrolysis/dehydration
• Oxidation/reduction
• Dephosphorylation
• Ligation reactions

Question 12

Give an overview of ATP

Answer 12

• Adenosine triphosphate
• Primary purpose of energy metabolism is to provide a constant supply of ATP to maintain cell growth etc.
• Produced through substrate-level phosphorylation (no O2) or through oxidative phosphorylation (O2)
• Hydrolysis at physiological pH releases 7.3 kcal as energy
• When left in solution for a long time at room temp, ATP will spontaneously (but slowly) release inorganic phosphate and be converted to ADP and eventually AMP

Question 13

Overview of ATP production

Answer 13

C6H12O6 + 6O2 ==> 6CO2 + 6H2O + 31ATP

Question 14

Order of production of ATP production

Answer 14

1. Glycolysis (1 glucose ==> 2 pyruvate)
2. Oxidative decarboxylation of pyruvate to form acetyl-CoA (one per pyruvate) loss of one CO2 per pyruvate
3. TCA cycle ==> introduction of 2 carbon atoms in form of acetyl-CoA, subsequent loss of 2CO2 per acetyl-CoA
4. Electron transport chain: energy which is stored in the form of energy rich H- (e.g. in NADH) is converted to water and ATP