1.4

Question 1

define catalyst

Answer 1

a substance that speeds up a reaction without changing the substances produced or being changed its self

Question 2

define enzyme

Answer 2

proteins that have specific shapes which act as biological catalyst controlling rate of the reactions taking place in an organism

Question 3

what type of a protein in an enzyme

Answer 3

globular

Question 4

what factors effect enzymes and why

Answer 4

pH and temperature as they affect the intramolecular bonds within the protein

Question 5

what is an anabolic reaction

Answer 5

a reaction that synthesises new molecules in a cell

Question 6

what is a catabolic reaction

Answer 6

a reaction which breaks down substances within a cell

Question 7

what is metabolism

Answer 7

the sum of anabolic and catabolic processes in a cell

Question 8

what is a metaboilc chain/pathway

Answer 8

a series of linked reactions in the metabolism of a cell

Question 9

what are intracellular enzymes

Answer 9

enzymes that catalyse reactions within the cell

Question 10

what are extracellular enzymes

Answer 10

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

Question 11

what is activation energy

Answer 11

the minimum amount of energy required to initiate a reaction

Question 12

how does an enzyme work

Answer 12

specific shape complementary to one substrate
substrate binds to active site which affects the bonds in the substrate making them easier to break
reacting substances are brought closer together making it easier for bonds to form between them
when the products are made they no longer fit in the enzyme so they are released

Question 13

what is the induced fit hypothesis

Answer 13

the active site is considered to have a more flexible shape and once the substrate enters the active site the shape if modified to form an active complex then relaxes when the products are released

Question 14

what are the control variables when looking at the effect of an enzyme on rate of reaction

Answer 14

conc of substrate & enzyme
temperature
pH

Question 15

what is molecular activity/turnover number

Answer 15

the number of substrate molecules transformed per minute by a single enzyme molecule

Question 16

what are enzyme inhibitors

Answer 16

substances that slow down enzymes or stop them from working

Question 17

what are the 2 main reversible inhibitors

Answer 17

competitive inhibitor
non-competitive inhibitor

Question 18

what is a competitive inhibitor

Answer 18

the inhibitor molecule is a similar shape to the substrate and they compete for the active site of the enzyme so level of inhibition is effected by conc of substrate and inhibitor

Question 19

what is a non-competitive inhibitor

Answer 19

inhibitor which forms a complex with enzyme or enzyme substrate complex by binding elsewhere on the enzyme (not to the active site) so only the concentration of inhibitors effects level of inhibition

Question 20

how does a irreversible inhibitor work and give examples

Answer 20

combines with the enzyme by permanent covalent bonds to groups vital for catalysis to occur causing the enzyme to become inactivated permanently
examples; poisons such as arsenic, cyanide and mercury

Question 21

what are regulatory enzymes

Answer 21

enzymes which have a site separate to the active site where another molecule can bind to have either a binding or inhibitory effect
they are found in complex metabolic pathways such as photosynthesis and respiration

Question 22

what is end-product inhibition and give an example

Answer 22

regulatory enzyme which is found near the beginning of pathways which is inhibited by on of the end products
example: PKF controls rate of respiration which is involved in the production of ATP