Introduction to metabolism

Question 1

Define metabolism.

Answer 1

The sum of chemical reactions continuously taking place in the body to maintain its proper function.

Question 2

Explain the basic concepts of cellular metabolism.

Answer 2

-Cellular metabolism involves complex sequences of controlled biochemical reactions, better known as metabolic pathways.

• These processes allow organisms to grow and reproduce, maintain their structures, and respond to environmental changes.

Question 3

Explain anabolism.

Answer 3

• The synthesis of substances which consumes energy. E.g Glucose to glycogen.
• Three steps in anabolism:
  1. Form precursors.
  2. Form complex molecules.
  3. Link these complex molecules together

Question 4

Explain catabolism.

Answer 4

-The breakdown of nutrients/ substances which releases energy. E.g Carbohydrates to glucose.

-Three stages:
1. Hydrolysis of complex molecules to their building blocks.
2. Conversion of building blocks to acetyl co-A
3. Oxidation of acetyl co-A; oxidative phosphorylation.

Question 5

Explain chemical reactions.

Answer 5

• Chemical reactions of metabolism are organised into metabolic pathways, in which one chemical is transformed into another by a sequence of enzymes.

-

Question 6

Explain metabolic pathways.

Answer 6

• A sequence of enzyme catalysed reactions that lead to the conversion of a substance into a final product.
• Consists anabolic and catabolic pathways.
• Enzyme inhibition or activation is used to control metabolic pathways & respond to changing needs.

Question 7

Explain energy transfer.

Answer 7

-The process of generating energy (ATP) from nutrients.

• ΔG (change in free energy) is the energy available to do work.
• Δ G is positive: Unfavourable reaction – biological process that requires energy - Endergonic reactions
• ΔG is negative – Favourable reaction – biological process releases energy - Exergonic reactions

Question 8

Outline the metabolic map that inter-relates carbohydrate, amino-acid and lipid metabolism

Answer 8

• The breakdown and synthesis of carbohydrates, proteins, and lipids connect with the pathways of glucose catabolism.
• The simple sugars are catabolized during glycolysis.
• The fatty acids from fats connect with glucose catabolism through acetyl CoA.
• The amino acids from proteins connect with glucose catabolism through pyruvate, acetyl CoA, and components of the citric acid cycle.