Enzymes and Energy Carriers

Metabolism

Sum of all chemical reactions that take place in an organism

• Catabolic Reaction (Large Molecules à Smaller Molecules eg Respiration)
• Anabolic Reaction (Smaller Molecules à Larger Molecules eg Photosynthesis)

 

Sources of Energy

The sun is the primary source of all energy. In photosynthesis, solar energy form the chemical bonds of carbohydrates

Cellular energy is the energy in chemical bonds. This energy is released in respiration to allow metabolism.

 

Enzyme

A protein/biological catalyst that alters the speed of a reaction without being used up in the reaction

 

Substrate

Substance with which an enzyme reacts

 

Product

The substance the enzyme forms after reacting with the substrate

 

Catabolic Enzyme

Amylase – Breaks down starch to maltose

 

Anabolic Enzyme

DNA Polymerase – Forms and repairs DNA

 

 

Factors Affecting Enzyme Activity

 

Temperature

• Humans: 37°C
• Plants: 20-30°C

pH

• Optimum pH is 7
• Pepsin in the stomach has an optimum pH of 2

A denatured enzyme has lost its shape and can no longer carry out its function.

 

Immobilised Enzymes

Bioprocessing

The use of enzyme-controlled reactions to make a produt

 

Bioreactor

A vessel or container in which living cells or their products are used to make a product

 

Enzymes that are attached to each other or to an inert substance are known as immobilised enzymes.

Advantages include

• Can be reused
• Easily separated from product
• Cheaper, no loss of efficiency

 

 

Advanced Enzymes and Energy Carries

Active Site

        Part of an enzyme that combines with the substrate

 

 

Induced fit Model-Mechanism of Enzyme Action

1. Substrate combines with active site of enzyme
2. Active site is cause to slightly change shape
3. Bonds in substrate are altered so that the product is formed
4. Products leave active site

 

Role of Energy Carriers

ATP – Adenosine Triphosphate

• High energy molecule – energy stored in phosphate bonds.
• Energy released when the phosphate bond is broken:

ATP => ADP + P + Energy

• Supplies energy for muscle contraction, nerve impulses

 

ADP – Adenosine Diphosphate

• Low energy molecule
• Uses energy and combines with a phosphate to form ATP

 

NAD⁺ - Nicotinamide Adenine Dinucleotide

• Used in respiration, low energy molecule
• Transfers electrons and hydrogen ion

                 NAD⁺ +2e^- + H⁺ => NADH (High Energy)

 

NADP⁺ - Nicotinamide Adenine Dinucleotide Phosphate

• Low energy molecule used in photosynthesis
• Transfers electrons and hydrogen ions

                NADP⁺ + 2e^- + H⁺ => NADPH (High Energy)

 

Remember: NADPH - Photosynthesis