Enzymes

Question 1

Enzymes

Answer 1

• Globular protein molecules (tertiary level of structure
• Biological catalysts - speed up a chemical reaction without being changed or used up
• Highly specific - an enzyme will catalyse only one reaction
• Activity is affected by pH, temperature, substrate and enzyme concentration
• Lower activation energy
• Reactions are reversible
• Very efficient - only small amounts needed and they can be used over again

Question 2

Intracellular enzymes

Answer 2

Made and work inside the cell
-They are found in the cytoplasm, nucleus, mitochondria and chloroplast.
Example - Enzymes involved in respiration and photosynthesis

Question 3

Extracellular enzymes

Answer 3

Made inside the cell and work outside the cell. Secreted by exocytosis
Example - digestive enzymes made in pancreas work in small intestine

Question 4

Metabolism

Answer 4

A combination of anabolic and catabolic reactions that are catalysed by enzymes

Question 5

Anabolic and Catabolic

Answer 5

Anabolic - 2 or more reactants form a product

Catabolic - a product splits into 2 or more reactants

Question 6

The collision theory

Answer 6

• Molecules move/have kinetic energy

- Successful collision reaction

Question 7

Enzyme structure

Answer 7

• 3D shape due to folding of alpha helix (tertiary structure)
• Active site is made up of a few amino acids and held by temporary bonds forming an enzyme-substrate complex

Question 8

Lock and Key Model

Answer 8

In the same way that a key fits into a lock, so a substrate is thought to fit into a n enzyme’s active site. The enzyme is like the lock, and the substrate is like the key.

Question 9

Induced fit model part 1

Answer 9

Similar to the lock and key model except that the active site changes shape slightly in the presence of the substrate e.g. like how a glove changes shape when a hand is put in.

Question 10

Induced fit model part 2

Answer 10

The changes of shape of both active sites and substrate bring reactive groups of enzyme and substrate close to each other, weakening bonds in the substrate so the reaction takes place at lower activation energy.

Question 11

Lysozyme

Answer 11

Lysozyme is an enzyme found in tears, saliva and mucus that helps to kill bacteria by braking down their cell walls. They then absorb water by osmosis and burst and die.