L13 - Introduction to Metabolism

Question 1

Fate of pyruvate:

Answer 1

Pyruvate to L-Lactate

Uses lactate dehydrogenase and NADH + H⁺ → NAD⁺ Lactate has COO^- OH and H and CH3 group on central carbon.

Question 2

Uses of thioester linkage:

Answer 2

1. High energy bond.
2. Acetyl CoA can store energy and transfer energy along metabolic pathways

Question 3

Name 3 uses of ATP:

Answer 3

1. ATP used for movement and contraction.
2. Na⁺/K⁺ pump for active transport
3. ATP phosphorylate protein with use of kinase makes it active/inactive Dephosphorylates protein with use of phosphatase makes it inactive/active

Add Pi to molecule - Phosphorylation

Question 4

Summary diagram that relates the main energy releasing metabolic pathways to each other

Answer 4

Glucose–GLYCOLYSIS–Pyruvate In Cytosol

Fatty Acid→Acetyl group by β-Oxidation in Matrix

Amino acid–TRANSAMINATION–‘Acetyl’ 2C unit

Pyruvate → Acetyl CoA

All go to Krebs cycle (TCA) in Matrix Oxidative Phosphorylation in IMM/Matrix 2H + O = H2O + ATP

Question 5

Explain the concept of controlled releases of energy in enzyme catalysed metabolic pathways.

Answer 5

It has a stepwise breakdown to release small amounts of energy constantly. Low E_a so enzymes can overcome energy easily.

Energy is released by each step at progressively lower levels.

In irreversible reactions, enzyme used can be controlled so this controls the metabolism. Energy used for a catabolic reaction can be carried by active carrier molecules and store for later use, for example, can be used in anabolic reactions.

Question 6

Examples of active carrier molecules and what they carry:

Answer 6

ATP - carry Pi (Phosphate)

NADH, FADH₂ - carry e^- and H

Acetyl CoA - carry acetyl group

Question 7

Definition of metabolism:

Answer 7

1. Comprise of anabolism and catabolism
2. Enzyme reaction of synthesis, breakdown and inter conversion of essential molecules

Question 8

Definition of catabolism: Give examples and locations:

Answer 8

Breakdown of complex substances to smaller ones. Produces energy in the form of ATP

e.g. Glycolysis Lipolysis Glycogenolysis

Location: Mitochondria

Question 9

Definition of anabolism: Give examples and locations:

Answer 9

Simpler substances made to complex ones.

Requires energy in the form of ATP

e.g. Gluconeogenesis Lipogenesis Glycogenesis

Location: Cytosol