B4 : Enzymes

Question 1

Catalyst

Answer 1

speeds up the rate of reaction

Question 2

Product

Answer 2

result of reaction

Question 3

Reactant

Answer 3

what is going to react

Question 4

Reactions in our body

Answer 4

enzymes catalyse every reaction in our body

Question 5

Enzymes

Answer 5

• Proteins
• Biological catalysts in metabolic reactions
• Specific (only a selective substrate they function with)
• Contain an active site
• Activity is affected by temperature, pH, and substrate concentration

Question 6

Substrate

Answer 6

molecule that an enzyme reacts with

Question 7

Lock and key

Answer 7

• A substrate will fit into an enzymes active site like a lock and a key
• No other substrate will work with an enzyme
• Each enzyme has a special shape with an area, the active site onto which the substrate molecules bind
• Very few amino acids form the active site making it a small component of a large molecule

Question 8

How enzymes work

Answer 8

• Biological catalysts that speed up the rate of metabolic reactions without being used up themselves.

Question 9

Catabolism

Answer 9

Reactions where larger molecules are broken down into smaller molecules by enzymes

Question 10

Anabolism

Answer 10

Reactions where small molecules are built up into larger more complex molecules by enzymes

Question 11

Induced fit hypothesis

Answer 11

• Modern interpretations suggest that in the presence of a substrate, the active site of an enzyme may change in order to fit the substrates shape
• The enzyme will wrap around the substate

Question 12

Denaturing of Enzymes

Answer 12

• Denaturing is the loss of biological properties (enzymes can no longer speed up the rate of reaction)
• Structure can be altered/denatured in extreme temperature and pH
• The active site is altered and changes shape which disables the ability for a substrate to bind to it therefore it cannot act as a catalyst
• Enzymes have an optimum temperature where it is the most efficient and when the temperature is higher than the optimum temperature the enzymes may denature stopping the reaction
• Enzymes have an optimum pH where it is the most efficient. pH level that is too high or too low will lead to the denaturing of enzymes

Question 13

Enzyme Graph

Answer 13

• Uncatalysed reaction/reaction without enzyme should be higher than the catalysed reaction
• Height from peak of the graph to the beginning of the reaction is the activation energy. Enzymes catalyse reactions by lowering activation energy so catalysed graph should have smaller activation energy
• Start of reaction is at the peak
• Smart and end at the same place
• If the graph is under the original beginning of the graph, it is exothermic reaction which is releasing heat and thermal energy, if it is above it is an endothermic reaction which absorbs heat and thermal energy
• The y-axis of the start of the graph to the end of the graph is the overall change in energy
• Free energy (all energy involved with reaction) against course of reaction

Question 14

Energy needed in enzymes

Answer 14

• Chemical reactions need energy to start them off called activation energy
• Energy is needed to break the existing chemical bonds inside molecules
• In the body, enzymes lower the activation energy of a reaction and so reduce the input of energy needed and allow reactions to take place at lower temperature