Factors Effecting Enzyme Activity

Question 1

what factors affect enzyme activity?

Answer 1

• temperature
• pH
• Substrate and enzyme concentration

Question 2

how do you calculate temperature coeffient of a reaction?

Answer 2

(rate of reaction at temperature x) divided by (rate of reaction at temperature x-10)

Question 3

why do enzymes denature from temperature?

Answer 3

enzymes are proteins so as temperatures get higher, bonds holding proteins together vibrate more. this happens until bonds strain and then break. this results in a change in the tertiary structure of the protein.

Question 4

what happens if an enzyme denatures?

Answer 4

the active site changes shape so it is no longer complementary to the substrate. the substrate can no longer fit so the enzy will no longer function as a catalyst.

Question 5

what does optimum temperature mean?

Answer 5

the temperature at which the enzyme has the highest rate of activity.

Question 6

what is a thermophile?

Answer 6

an organism adapted to living in hot environments.

Question 7

which type of cat demonstrates the effect of temperature on enzymes?

Answer 7

siamese cats

Question 8

how do siamese cats highlight the efect of temperature on enzymes?

Answer 8

the enzyme tryosinase is responsible for catalysing melanin production. siamese cats have a mutation wherby their tryosinase is denatured and inactive at body temperatures, but their tails, feet and extremeties have darker pigments as it is cooler.

Question 9

what bonds hold proteins in their three dimensional shapes?

Answer 9

hydrogen bonding and ionic bonding between amino acid R groups. the bonds result from interactions between the polar and charged R-groups present on the amino acids forming the primary structure.

Question 10

do acidic environments have more or less hydrogen ions?

Answer 10

more

Question 11

what is renaturation?

Answer 11

if the pH changes from the optimum, the active site is altered. renaturation is whereby the normal shape of the enzyme is restored if it goes back to its optimum pH.

Question 12

what happens if the pH changes too much?

Answer 12

the structure of the enzyme will be irreversibly altered. the enzyme has now denatured.

Question 13

why does pH impact the rate fo reaction?

Answer 13

hydrogen ions interact with polar and charged R-groups. changing the pH changes the degree of this interaction.

Question 14

what happens if the pH is too low?

Answer 14

more hydrogen ions are present so less R-groups can interact with each other. this causes bonds to break and the enzyme changes shape.

Question 15

what is the optimum pH for saliva (amylose) ?

Answer 15

7-8

Question 16

what is the optimum temperature for the gastric juice?

Answer 16

1-2

Question 17

what is the optimum temperature for pancreatic juice?

Answer 17

8 - slightly acidic.

Question 18

what happens when substrate concentration increases?

Answer 18

a higher collision rate with active sites so more enzyme-substrate complexes are formed.

Question 19

what happens when enzyme concentration increases?

Answer 19

a higher collision rate as more active sites in a given area.

Question 20

what happens at the vmax?

Answer 20

all active sites are occupied by substrate and enzyme-substrate complexes cant be formed until products are released from active site.

Question 21

what is a limiting factor?

Answer 21

the thing that is limited. if substrate pH is high, there will not be enough active sites - enzyme concentration is limiting factor. if enzyme concentration is raised, there m not be enough substrate.

Question 22

why is catalase good for effects of enzyme activity?

Answer 22

present in plant and animal tissue so it is readily available.

Question 23

what is the role of catalase?

Answer 23

catalyse the breakdown of hydrogen peroxide into water and oxygen.

Question 24

how do you use catalase to investigate the effects of different factors on enzyme activity?

Answer 24

the volume of gas collected in a set length of time will determine the rate of reaction.

Question 25

what is a serial dilution?

Answer 25

a repeated, stepwise dilution of a stock solution of known concentration.

Question 26

why are serial dilutions useful even if the initial concentration is unknown?

Answer 26

the serial dilution concentrations are relative

Question 27

how do you do a serial dilution?

Answer 27

• add 1ml of stock solution into a test tube. add 9ml of distilled water. this gives a 1/10 dilution as 10% is concentrated.
• add 1ml of the 1/10 solution to another test tube. add 9ml of distilled water. this will give a 1/100 dilution as 1% is concentrated.

Question 28

what does the concentration go by down each time for a serial dilution?

Answer 28

divided by 10 each time.