M2 chapter 4: enzymes

Question 1

what is an enzyme?

Answer 1

protein that speeds up the rate of a chemical reaction. biological catalysts

Question 2

what is a biological catalyst?

Answer 2

found in living organisms

Question 3

what is a catalyst?

Answer 3

a substance which speeds up a chemical reaction without being used up in the reaction itself

Question 4

what are intracellular enzymes?

Answer 4

enzymes that works inside a cell eg catalyse

Question 5

what are extracellular enzymes?

Answer 5

enzymes that work outside a cell eg amylase and trypsin

Question 6

what is the structure of enzymes?

Answer 6

globular proteins
have an active site which substrate binds to.
active site shape determined by proteins tertiary structure

Question 7

what is a enzyme substrate complex?

Answer 7

a temporary molecule formed when the substrate with a specific complementary shape binds to the enzyme

Question 8

how do enzymes speed up reactions?

Answer 8

they lower the activation energy needed for a reaction so they can happen at lower temperatures speeding up the rate of reaction

Question 9

how does the enzymes lower the activation energy?

Answer 9

-if substrate molecule needs to break down the active site puts strain on the bonds between molecules so it can break more easily
-if substrate molecules need to bond together the active site pulls them closer together reducing repulsion making it easier to bond

Question 10

what is the lock and key model?

Answer 10

The active site of an enzyme is structured to fit a specifically shaped substrate. Once the substrate binds to the active site, the enzyme will facilitate the reaction and release products of the reaction.

Question 11

what is the induced fit model?

Answer 11

a substrate binds to an active site and both change shape slightly, creating an ideal fit for catalysis.

Question 12

what factors affect enzyme activity?

Answer 12

temperature
pH
substrate concentration
enzyme concentration

Question 13

how does temperature effect enzyme activity?

Answer 13

increase rate of reaction as more heat means more kinetic energy so the molecules move faster. this means the enzyme and substrates are more likely to collide and form an enzyme substrate complex

Question 14

what is the optimum temperature for enzymes?

Answer 14

37 degrees Celsius

Question 15

what else in the reaction does the temperature also increase?

Answer 15

energy of collisions meaning each collision is more likely to be a successful collision

Question 16

what happens if the temperature gets too high?

Answer 16

reaction will stop because the enzyme molecules will vibrate too much which causes bonds which holds the enzymes shape to break

Question 17

what is a Q10 value?

Answer 17

shows how rate of reaction changes when temperature in creases by 10 degrees

Question 18

what effect does pH have on rate of reaction?

Answer 18

enzymes operate the fastest at an optimum pH usually pH 7.

Question 19

what happens to enzyme activity when the pH goes above and below the optimum pH?

Answer 19

Above and below the optimum pH the H+ and the OH- ions break the hydrogen bonds which hold the enzymes tertiary structure in place. denaturing the enzyme

Question 20

what effect does enzyme concentration have on enzyme activity?

Answer 20

more enzymes in a solution increases the rate of reaction because their is more enzymes for the substrate to collide with.

Question 21

what is a saturation point?

Answer 21

when all the active sites are full so a higher concentration of enzymes or substrates wouldn’t make a difference

Question 22

what effect does substrate concentration have on enzyme activity?

Answer 22

more substrate in a solution increases the rate of reaction because their is more substrate to collide with the active site

Question 23

what is a cofactor?

Answer 23

a non protein substrate bound to an enzyme

Question 24

what is a inorganic cofactor?

Answer 24

works by helping the enzyme and substrate bind together . it isn’t used up or changed in anyway

Question 25

what is a organic cofactor?

Answer 25

Aka a coenzyme
participates in the reaction so is changed by it
move chemical groups between enzymes as carriers

Question 26

what is a prosthetic group?

Answer 26

a cofactor which is tightly bound to the enzyme.
eg: zinc ions are a prosthetic group for carbonic anhydrase

Question 27

what are enzyme inhibitors?

Answer 27

bind to enzyme to stop them from working
2 types- competitive and non competitive

Question 28

what do competitive inhibitors do?

Answer 28

compete with substrate to bind to active site as it is the similar shape to block it
if high conc of inhibitor little substrate will bind to enzyme

Question 29

what would a higher concentration of substrate effect a competitive inhibitor in a reaction?

Answer 29

faster rate of reaction to a certain point as more substrate can compete with the inhibitors to bind to the active site

Question 30

what do non competitive inhibitors do?

Answer 30

bind to enzymes away from active site at allosteric site. cause active site to change shape so substrate can’t bind to it

Question 31

what effect does a higher concentration of substrate have on a non competitive inhibitor?

Answer 31

no difference as the substrate can’t bind to the active site

Question 32

what makes a inhibitor irreversible?

Answer 32

strong covalent bonds

Question 33

what makes a inhibitor reversible?

Answer 33

weak hydrogen and ionic bonds

Question 34

what sort of drugs are inhibitors?

Answer 34

antiviral drugs such as reverse transcriptase
antibiotics such as penicillin

Question 35

what are metabolic poisons?

Answer 35

interfere with metabolic reactions in cells and can cause damage and death

Question 36

what are some examples of metabolic poisons?

Answer 36

cyanide
malonate
arsenic

Question 37

what is product inhibition?

Answer 37

when a product inhibits the enzyme that has catalysed its formation.

Question 38

what is end product inhibition?

Answer 38

final product in metabolic pathway inhibits an enzyme that acts earlier on in pathway.
this regulates the pathway and controls the amount of end product made

Question 39

Are product and end production inhibition reversible?

Answer 39

yes as levels of product decrease so do the levels of inhibition therefore enzyme can function again and more product can be made.