ENZYMES

Question 1

Enzymes (biological catalysts)

Answer 1

proteins that speed up metabolic reactions by lowering activation energy, without being used up in the reaction

Question 2

specificity enzymes

Answer 2

each enzyme is specific to a particular substrate due to enzyme active site

Question 3

enzyme structure

Answer 3

globular proteins with specific tertiary structure that determines its active sites shape

Question 4

lock and key hypothesis

Answer 4

substrate is complimentary to enzyme active site
substrate fits perfectly like a lock

Question 5

induced fit hypothesis

Answer 5

enzymes active site slightly changes shape to accommodate for the substrate
this facilitates the reaction

Question 6

factors affecting enzyme activity

Answer 6

• temp
• pH
• substrate conc
• enzyme conc
• inhibitors

Question 7

low temperature affect on enzyme activity

Answer 7

molecules have little kinetic energy
so few successful collisions between enzymes and substrates
activation energy required isnt reached
so enzyme-substrate complexes formed slow

Question 8

too high temp affect on enzyme activity

Answer 8

thermal energy put in
breaks h bonds in enzymes tertiary structure
enzyme structure is disrupted
active site changes shape (enzyme denatures)
enzyme no longer complimentary to active site
no more reactions

Question 9

affect of too acidic or alkaline pH on enzyme activity

Answer 9

h+ (acid) or OH- (alkaline) ions from conditions disrupts h bonds and ionic bonds in enzyme
enzymes active site changes shape
so enzyme denatures
limiting reaction rate

Question 10

substrate concentration limiting

Answer 10

as enzyme conc increases the rate of reaction increases, until substrate is limiting so the rate levels out (plateaus)

Question 11

competitive inhibitors

Answer 11

molecules that compete with the substrate for binding to the enzyme’s active site.
inhibitor has similar shape to substrate
so they bind to active site
reducing the rate of reaction
but eventually the rate of reaction is the same as without the inhibitor (graph with inhibitor plateaus at rate that is the same as without inhibitor)

Question 12

non competitive inhibitors

Answer 12

inhibitors bind to allosteric site on enzyme
causing a change in shape of active site
so the enzyme is no longer complimentary
denaturing it
dropping the rate of reaction

Question 13

intracellular enzymes

Answer 13

enzyme works inside cell
e.g: catalase breaks down h2o2 to h2o and o2 in perixosomes

Question 14

extracellular enzymes

Answer 14

secreted outside of cell
e.g: amylase is secreted from pancreas but breaks starch into maltose in intestines

Question 15

enzyme cofactors

Answer 15

non-protein molecules required for function of protein

Question 16

inorganic cofactors

Answer 16

metal ions that assist enzymes with catalysing reactions

Question 17

organic cofactors

Answer 17

organic molecules (e.g vitamins) that temporarily bind to enzyme to assist catalysing reactions
(e.g Vitamin K helps blood-clotting enzymes)

Question 18

prosthetic groups

Answer 18

tight and permanently covalently bound cofactors that are attached to enzymes
(e.g heme group is in haemoglobin and contains iron to help oxygen bind)

Question 19

enzymes use in industry

Answer 19

biosensors to measure blood glucose
waste water treatment
baking uses amylase to help bread rise
lactase breaks down lactose in milk for lactose-free milk
protease in detergent to clean blood from clothes
insulin can be lab made
alcohol fermentation using amylase