CHEM

What is enzyme regulation?

Molecules activate or inhibit enzymes to control metabolic pathway activity

What is glycolysis?

Glucose is broken down into pyruvate to produce ATP.

PFK-1 is a major regulatory enzyme

What does high ATP/AMP do?

High ATP inhibits PFK-1 → glycolysis decreases High AMP activates PFK-1 → glycolysis increases

What is fermentation?

NADH is converted back into NAD+ so glycolysis can continue Pyruvate → lactate, or ethanol + CO₂

What is gluconeogenesis?

The liver makes new glucose from lactate, glycerol and glucogenic amino acids

What are the characteristics of gluconeogensis?

increases during fasting.

Stimulated by glucagon.

Suppressed by insulin.

Requires ATP/GTP

What is the TCA cycle?

Acetyl-CoA is oxidised, producing electron carriers that supply the ETC.

3 NADH 1 FADH₂ 1 GTP 2 CO₂

What happens of oxygen isnt present in the TCA cycle

Without oxygen, NAD+ regeneration decreases → TCA activity slows

What is the electron transport chain

Electrons from NADH and FADH₂ move through the ETC, driving proton pumping

What happens of etc is inhibited?

ETC inhibition → NADH accumulates → ATP production decreases

What is ATP synthase?

Protons flow down their electrochemical gradient through ATP synthase, driving ATP production

What do F0 and F1 do in ATP synthase?

F₀ allows proton movement

F₁ contains the catalytic sites for ATP synthesis

What does blocking ATP synthase do?

Blocking ATP synthase decreases ATP production and initially increases the proton gradient

What is B-oxidation?

Fatty acids are broken into 2-carbon acetyl-CoA units, occurs in mitochondrial matrix, Each cycle produces 1 NADH and 1 FADH₂

What is ketogenesis?

Excess acetyl-CoA is converted into ketone bodies in liver mitochondria

What happens to ketogenesis during fasting?

Prolonged fasting increases ketogenesis because fatty acid oxidation produces more acetyl-CoA than the TCA cycle can fully process

What is the urea cycle?

The liver converts toxic nitrogen from amino acid breakdown into urea

What is fatty acid synthesis?

Excess energy is stored by building fatty acids using NADPH, promoted by insulin

In the fed state (insulin) what happens?

Glycolysis increases, Glycogen synthesis increases Fat synthesis increases Gluconeogenesis decreases

In the glucagon state (fasting) what happens?

Liver glycolysis decrease, Gluconeogenesis increase Glycogen breakdown increase, Fat breakdown increase

What does high glucagon do?

High glucagon promotes liver glucose production to maintain blood glucose during fasting

What does an ETC inhibtor do?

Blocks electron transfer → NADH oxidation decreases → NADH accumulates → ATP production decreases

What does an ETC uncoupler do?

Allows H+ to bypass ATP synthase → proton gradient decreases → ATP synthesis decreases, while electron transport may increase

What is the warburg effect?

Cancer cells often favour glycolysis and lactate production despite oxygen being available