Enzymes

Question 1

what type of proteins are enzymes

Answer 1

globular

Question 2

what are the 2 main types of reactions that enzymes catalyse

Answer 2

anabolic and catabolic

Question 3

what are anabolic reactions

Answer 3

smaller molecules synthesise into larger molecules (requires energy)

Question 4

what are catabolic reactions

Answer 4

breakdown of larger molecules into smaller ones (releases energy)

Question 5

what is metabolism

Answer 5

the sum of all reactions that take place within a cell/organism

Question 6

what does the induced fit hypothesis suggest

Answer 6

the active site of the enzyme changes shape slightly as the substrate binds with it - which puts a strain on the bonds of the substrate molecule and lowers the activation energy for the reaction

Question 7

what interactions are included in the tertiary structure of a protein

Answer 7

hydrogen bonds, ionic bonds, disulfide bridges and hydrophobic interactions

Question 8

what are intracellular enzymes

Answer 8

site of action is within the cell (majority of enzymes)

Question 9

give examples of intercellular enzymes

Answer 9

phosphorylases, catalase and ATPase

Question 10

what are extracellular enzymes

Answer 10

site of action is outside the cells

Question 11

give examples of extracellular enzymes

Answer 11

amylase, maltase and trypsin

Question 12

how does temp affect enzyme activity

Answer 12

as temp increases, so does kinetic energy, more successful collisions, more e-s-c are formed
beyond optimum, strains on bonds break meaning tertiary structure changes and enzyme becomes denatured

Question 13

what is temperature coefficient, Q10

Answer 13

a measure of how much the rate of reaction increases with a 10^C increase in temp

Question 14

what is the optimum temp of thermus aquaticus and its biological uses

Answer 14

70^C
used in PCR

Question 15

what is the optimum temp of psychophiles and their biological uses

Answer 15

0-10^C
detergent industry

Question 16

what is the optimum temp of thermophiles and their biological uses

Answer 16

50-80^C
washing powder

Question 17

what is the optimum temp of the human stomach and its biological use

Answer 17

37^C
break down of food molecules

Question 18

how does pH affect enzyme activity

Answer 18

when pH differs slightly from optimum, active sit changes shape due to bonds breaking, if optimum pH is restored, it resumes its normal shape (renaturation)
if it differs significantly, it changes irreversibly (denaturation)

Question 19

suggest the optimum pH of salivary amylase

Answer 19

7

Question 20

suggest the optimum pH of pancreatic lipase

Answer 20

7-8

Question 21

suggest the optimum pH of pepsin

Answer 21

2

Question 22

suggest the optimum pH of pancreatic amylase

Answer 22

7

Question 23

suggest the optimum pH of trypsin

Answer 23

7-8

Question 24

how does substrate concentration affect enzyme activity

Answer 24

as substrate conc increases there are more successful collisions for more e-s-c form
however at a certain point, the point of saturaction, Vmax is reached and so substrate conc has no further affect

Question 25

how does enzyme concentration affect enzyme activity

Answer 25

Vmax can be increased if the enzyme conc is increased as there are more active sites for substrate molecules to occupy - rate of reaction increases until a new Vmax is reached

Question 26

how does competitive inhibition work

Answer 26

both the competitive inhibitor and the substrate have a similar shape to the active site so the c.i can bind to active site preventing the substrate from binding and forming an e-s-c only binds temporarily so effect is reversible

Question 27

give examples of competitive inhibition

Answer 27

statins aspirin

Question 28

how does non competitive inhibition work

Answer 28

n.c.i binds to enzyme at allosteric site causing the tertiary structure of the enzyme to change (bonds are disrupted) enzymes active site is no longer complementary to substrate (binds permanently0

Question 29

give examples of non competitive inhibition

Answer 29

organophosphates proton pump inhibitors (PPIs)

Question 30

how does end product inhibition work

Answer 30

the substrate forms an e-s-c and product is formed this product may directly act as an n.c.i meaning the enzymes active site is no longer complementary and reaction is inhibited

Question 31

give an example of end product inhibition

Answer 31

PFK (phosphofructokinase) - during glycosis

Question 32

what is a cofactor

Answer 32

a non-protein component of an enzyme that helps them carry out their catalytic function

Question 33

what are the 2 types of cofactors

Answer 33

inorganic cofactors coenzymes

Question 34

give examples of inorganic cofactors

Answer 34

iron ions, calcium ions, chloride ions, zinc ions

Question 35

what are prosthetic groups

Answer 35

inorganic ions that tightly bind to an enzyme to activate them

Question 36

give an example of a prosthetic group

Answer 36

zinc ions tightly binding to carbonic anhydrase to activate its role in metabolising CO2

Question 37

what are coenzymes

Answer 37

organic molecules which do NOT bind permanently to enzymes

Question 38

give examples of coenzymes

Answer 38

vitamin B3 (used to synthesise coenzyme NAD) vitamin B5 (used to synthesise coenzyme A)

Question 39

what do CL- ions bind to

Answer 39

amylase

Question 40

what do ZN2+ ions bind to

Answer 40

carbonic anhydrase

Question 41

what are precursor enzymes

Answer 41

enzymes that are produced in an inactive form

Question 42

how can precursors be activated

Answer 42

action of another enzyme environmental conditions

Question 43

why is it important that pepsinogen ( a precursor) is not activated until it enters the stomach

Answer 43

to prevent it from digesting the stomachs own cells