Topic 1 - 1.4 Enzymes

Question 1

Describe a catalyst

Answer 1

Is a substance which speeds up a reaction without changing the substances produced or being changed itself.

Question 2

Describe an enzyme.

Answer 2

Enzymes are proteins that have a very specific shape as a result of their primary, secondary, tertiary and quaternary structures. They act as biological catalysts and each enzyme will only catalyse a specific reaction or group of reactions.
They are globular proteins which have bonded in a certain way to have a specific active site to bond with a specific substrate

Question 3

What does it mean that enzymes have specificity?

Answer 3

Is the characteristics of enzymes that means that, as a result of the very specific shapes resulting from their tertiary and quaternary structures, each enzyme will only catalyse a specific reaction or group of reactions

Question 4

What is an anabolic reaction?

Answer 4

Is the reaction that builds up and catalyses the production of new molecules

Question 5

What is a catabolic reaction?

Answer 5

Is a reaction which breaks down substances within a cell

Question 6

What is metabolism?

Answer 6

Is the sum of all the anabolic and catabolic reactions in the body

Question 7

What is a metabolic chain?

Answer 7

Is a series of linked reactions in the metabolism of a cell

Question 8

What are intracellular enzymes?

Answer 8

Are enzymes that catalyse reactions within the cell

Question 9

What are extracellular enzymes?

Answer 9

Are enzymes that catalyse reactions outside of the cell in which they were made

Question 10

What is the activation energy of a reaction?

Answer 10

Is the energy needed for a reaction to begin.

Question 11

What is a substrate?

Answer 11

Is the molecule or molecules on which an enzyme acts

Question 12

Describe the lock and key theory

Answer 12

The active site of an enzyme has a specific shape, on,y one type of substrate will fit into that active site. It is this which give enzymes their specificity. The active site affects the bonds in the substrate making it easier for the substrate to be broken down.

Question 13

Describe the active site of an enzyme.

Answer 13

Is the area of an enzyme that has a specific shape in which the substrate fits

Question 14

What is the induced-fit hypothesis?

Answer 14

It suggests that the active site is more flexible than previously believed. It suggests that once the substrate enters the active site of the enzyme the active site mounds around the substrate to form the substrate complex, once the products leave the enzyme the enzyme reverts back to a ‘normal’ relaxed state.

Question 15

How does an enzyme affect the activation energy of a reaction?

Answer 15

Enzymes lower the activation energy of reactions reducing the amount of energy needed for the reaction to take place.