Lecture 15 - glycolysis

Question 1

Nucleoside diphosphate kinases

Answer 1

Unspecifically converts all types of NTPs into NDPs and produces energy equivalent to ATP

Question 2

Oxidising agents: what do they do and what are examples?

Answer 2

Accepts electrons, oxidising the other compound and being reduced itself

NAD⁺ + H⁺ + 2e⁻ ⇌ NADH
FAD⁺ + H⁺ + 2e⁻ ⇌ FADH₂

Question 3

Neutralising agents: what do they do and what are examples?

Answer 3

Loses electrons, reducing the other compound and being oxidised itself

NADPH ⇌ NADP⁺ + H⁺ + 2e⁻

Question 4

Glycolysis

Answer 4

C₆H₁₂O₆ + 2ADP + 2NAD⁺ + 2 Pᵢ ->
2C₃H₃O₃⁻ + 2ATP + 2NADH + 2H⁺ + 2H₂O

As one molecule is broken down into 2 pyruvates, 2 ATP is generated and 2 NAD+ are reduced by 4 electrons to form NADH

Question 5

Pyruvate metabolism: aerobically

Answer 5

Aerobically - citric acid (Krebs) cycle:
1) Link reaction:
* 2Pyruvate is decarboxylated into acetate and then reacts with CoA to form 2acetyl CoA
2) Citric acid cycle:
* 2Acetyl CoA reacts with 2oxaloacetate and is then decarboxylated and oxidised to produce 24e⁻ which is then sent down the electron transport chain to produce ATP

Overall reaction:
C₆H₁₂O₆ + 6O₂ -> 12H₂O + 6CO₂

Question 6

Pyruvate metabolism: anaerobically (in microorganisms)

Answer 6

Anaerobically (microorganisms) - ethanol:
* Pyruvate is converted to acetaldehyde by pyruvate decarboxylase and then ethanol by alcohol dehydrogenase
* This reaction produces 2ATP, 2CO₂, and 2H₂O but doesn’t result in a net oxidation/reduction change (NAD⁺/NADH not involved)

Question 7

Pyruvate metabolism: anaerobically (in muscle cells/RBC)

Answer 7

Anaerobically (muscle cells) - lactate:
* Lactate hydrogenase converts pyruvate into lactate
* This reaction produces 2 ATP and does not result in any net change in oxidation/reduction (NAD⁺/NADH not involved in the reaction)