Enzymes

Question 1

Metabolism

Answer 1

The rate at which chemical reactions take place in the body

Question 2

Turnover number

Answer 2

How many molecules of substrate an enzyme can convert into product per unit of time

Question 3

Active site

Answer 3

The specific 3D site on an enzyme molecule to which the substrate binds by weak chemical bonds.

Question 4

Activation energy

Answer 4

The energy needed to start a chemical reaction, by breaking the existing bonds in the molecule.

Question 5

Optimum temperature

Answer 5

The temperature at which the rate of enzyme-catalysed reactions is highest.

Question 6

Cofactors

Answer 6

Non-protein molecules which modify the chemical structure of an enzyme so that it may function more effectively

Question 7

Prosthetic groups

Answer 7

Organic molecules which form a permanent attachment to the enzyme

Question 8

Coenzymes

Answer 8

Small, non-protein, organic molecules, not permanently attached to the enzyme and help enzymes and substrates bond with each other.

Question 9

Activators

Answer 9

Inorganic metal ions which form a temporary attachment to the enzyme and alter the active site so a reaction is more likely to take place

Question 10

Inhibitor

Answer 10

A substance that slows down or stops the rate of enzyme-controlled reactions

Question 11

Metabolic pathway

Answer 11

A series of enzyme controlled reactions

Question 12

Multi-enzyme pathway

Answer 12

Where each reaction in a metabolic pathway is catalysed by a different enzyme

Question 13

End product inhibition

Answer 13

Where the multi-enzyme pathway is controlled by the end product

Question 14

Negative feedback

Answer 14

The output from a system affects the input

Question 15

Anabolic reaction

Answer 15

Building up of molecules e.g. protein synthesis

Question 16

Catabolic reaction

Answer 16

Breaking down of molecules e.g. digestion

Question 17

Enzyme specificity

Answer 17

An enzyme is specific for its substrate

Question 18

Enzyme-Substrate complex

Answer 18

Temporary structure formed during an enzyme-catalysed reaction in which the substrate and enzyme temporarily bind so that the substrate is close enough to react

Question 19

Competitive inhibition

Answer 19

A reduction in the rate of enzyme-controlled reactions by a molecule or ion that has a complementary shape to the active site, similar to the substrate, and binds to the active site, preventing the substrate from binding.

Question 20

Allosteric site

Answer 20

A site other than the active site

Question 21

Non-competitive inhibition

Answer 21

An atom, molecule or ion that reduces the rate of an enzyme by binding at a position other than the active site, altering the shape of the active site and preventing the substance from successfully binding to it.

Question 22

Immobilised enzyme

Answer 22

Enzyme molecules bound to an inert material, over which the substrate molecules move.

Question 23

Biosensor

Answer 23

A device that combines a biomolecule, such as an enzyme, with a transducer, to produce an electrical signal which measures the concentration of a chemical.

Question 24

Denaturation

Answer 24

The permanent damage to the structure and shape of a protein molecule e.g. an enzyme, due to, for example, high temperatures of extreme pH

Question 25

Inactivation

Answer 25

Reversible reduction of enzyme activity at low temperature as molecules have insufficient kinetic energy to form enzyme-substrate complexes

Question 26

Limiting factor

Answer 26

A factor where increasing its value increases the rate of reaction

Question 27

Saturated enzyme

Answer 27

When all the enzyme’s active sites are occupied by substrate.