Intro to Metabolism

Question 1

What is metabolism

Answer 1

• Refers to all the chemical processes going on continuously inside your body that allow life and normal functioning.
• These processes include those that break down nutrients from our food, and those that build and repair our body.
• The metabolic rate measures the amount of energy used to maintain life
• An organism must ingest a sufficient amount of food to maintain its metabolic rate if the organism is to stay alive for very long.

Question 2

What is Catabolism and Anabolism

Answer 2

• Our metabolism is complex- put simply it has 2 parts, which are carefully regulated by the body to make sure they remain in balance.
• Catabolism: the breakdown of food components (such as Carbohydrates, proteins and dietary fats) into their simpler forms, which can then be used to provide energy and the basic building blocks needed for growth and repair.
• Anabolism: the part of metabolism in which our body is built or repaired. Anabolism requires energy that ultimately comes from our food. When we eat more than we need for daily anabolism, the excess nutrients are typically stored in our body as fat.

Question 3

Comparing catabolism and anabolism

Answer 3

Catabolism:
- Breaks down big complex molecules into smaller, easier to absorb molecules
- Releases energy
- Required to perform different activities in living entities
- Examples:
- Proteins breaking down to amino acids
- Glycogen breaking down into glucose
- Triglycerides breaking down into fatty acids

Anabolism:
- Builds molecules required for the body’s functionality
- Requires energy
- Required for maintenance, growth and storage
- Examples:
- Formation of polypeptides from amino acids
- Glucose forming glycogen for storage

Question 4

Enzymes and Metabolism

Answer 4

• Specific proteins in body control the chemical reactions of metabolism
• Thousands of metabolic reactions happen at the same time- all regulated by the body- to keep our cells healthy and working

Question 5

Features of Enzymes

Answer 5

1. Are proteins
   
   2. Catalyse (speed up) chemical reactions
   3. Are not used up in the reaction (they can be recycled)
   4. Are reaction- specific (one enzyme, one reaction)
   5. Each enzyme works under specific conditions e.g. pH & temperature
   6. Work by lowering the activation energy
   7. Thought to work on and lock- key principle
   8. Can work in systems with coenzymes & cofactors
   9. Denatured when heated beyond optimal temp

Question 6

6. Activation energy

Answer 6

• Energy needed to start a chemical reaction

Question 7

7. Lock- key model

Answer 7

• An analogy to explain the specific action of an enzyme with a single substrate
• Substrate- molecules which enzymes act on
• Active site- where the substrate attaches to form an enzyme- substrate complex
• The enzyme can either weaken or form chemical bonds, resulting in the substrate breaking down or joining of two substrates together
• The enzyme is unaltered during the reaction and is free to catalyse another reaction

Question 8

9. Denaturing enzymes

Answer 8

• The active site is the specific portion an enzyme that attaches to the substrate
• The specific shape of the active site must be maintained if the protein is to function properly
• If the shape of the active site is altered (e.g. by heating) or blocked (e.g. by a poison) the enzyme will no longer function and is said to be denatured.