cc4 - enzymes

Question 1

metabolism

Answer 1

sum of all the enzyme controlled chemical reactions taking place in a cell

Question 2

2 main types of reactions that make up metabolism

Answer 2

anabolic
catabolic

Question 3

anabolism

Answer 3

set of metabolic pathways that synthesise complex molecules from smaller, simpler ,molecules

Question 4

catabolism

Answer 4

set of metabolic pathways that breakdown complex molecules into smaller, simple molecule

Question 5

enzyme

Answer 5

biological catalyst used to speed up rate of intracellular + extracellular biochemical reactions
not used up or permanently altered

Question 6

intracellular enzyme

Answer 6

enzyme that acts within cells
e.g: catalase

Question 7

extracellular enzyme

Answer 7

enzyme secreted by cells + functions outside of cells
e.g: amylase

Question 8

active site of enzyme

Answer 8

region of enzyme that is complementary to shape of a specific substrate
substrate binds + reaction takes place

Question 9

why is active site described as specific

Answer 9

3D structure of each enzyme (including active site) is unique due to presence of different side chains + branches
only specific substrates complementary to active site can bind

Question 10

activation energy

Answer 10

minimum amount of energy required for a reaction to take place

Question 11

catalysis

Answer 11

increase in rate of chemical reaction using a catalyst (such as an enzyme)
catalyst lowers activation energy of reaction

Question 12

lock and key model

Answer 12

1. substrate + active site of enzyme come into contact
2. substrate binds, enzyme-substrate complex forms
3. reaction takes place, products formed in enzyme-product complex
4. products released from active site
   active site now free to bind to another substrate

Question 13

induced fit hypothesis

Answer 13

model of enzyme action stating that once a specific substrate binds to active site, enzyme undergoes subtle conformational changes
puts strain on substrate, lowering activation energy for reaction

Question 14

factors affecting rate of enzyme-controlled reaction

Answer 14

temperature
pH
substrate concentration
enzyme concentration

Question 15

how temperature affects rate of enzyme-controlled reactions

Answer 15

as temp increases, molecules have more kinetic energy
molecules moved faster + collide more frequently
more ES complexes form
tate of reaction increases
rate peaks at optimum temperature

Question 16

how increasing temp above optimum affects rate of enzyme-controlled reaction

Answer 16

increased vibration break H + ionic bonds in tertiary structure
active site changes shape, enzyme is denatured
no more ES complexes form
rate of reaction decreases

Question 17

how pH affects rate of enzyme-controlled reactions

Answer 17

enzymes have optimum pH
pH shifts from optimum
H + ionic bonds in tertiary structure are altered
interaction of polar + charged R groups changes
active site changes shape, enzyme is denatured
rate of reaction decreases

Question 18

buffer

Answer 18

molecules maintaining constant pH in a solution when small volumes of acid (H+) or base (OH-) are added

Question 19

how substrate concentration affects rate of enzyme-controlled reaction

Answer 19

if enzyme concentration is fixed, rate of reaction increases proportionally to substrate concentration
once all active sites are full, rate of reaction remains constant (graph plateaus)
enzyme concentration is limiting factor

Question 20

how enzyme concentration affects rate of enzyme-controlled reaction

Answer 20

if substrate concentration is fixed, rate of reaction increases proportionally to enzyme concentration
when all substrates occupy active sites, rate of reaction plateaus (substrate concentration is limiting factor)

Question 21

competitive inhibitor

Answer 21

molecule which competed for active site of enzyme, blocking it + preventing substrate from binding

Question 22

is competitive inhibition temp or permanent

Answer 22

generally temp
some cases (e.g: aspirin) may be permanent

Question 23

how increasing substrate concentration affects competitive inhibition

Answer 23

increase in substrate concentration
more substrate than inhibitor
rate of reaction increases

Question 24

non-competitive inhibitor

Answer 24

inhibitor binds to different part of enzyme (allosteric site)
tertiary structure of enzyme (including active site) changes shape
active site no longer complementary to substrate
substrate can’t bind + enzyme is inhibited

Question 25

is non-competitive inhibition temp or permanent

Answer 25

permanent

Question 26

how increasing substrate concentration affects non-competitive inhibition

Answer 26

won’t overcome effect of non-competitive inhibitor

Question 27

immobilised enzymes

Answer 27

enzymes attached to inert, insoluble material over which substrate passes + reaction takes place

Question 28

example of application of immobilised enzyme

Answer 28

biosensors

Question 29

why immobilised enzymes important in industrial processes

Answer 29

enable enzymes to be reused
improves enzyme stability in variable/extreme temps + pHs
increases efficiency of reactions