enzymes DEFINITELY IN EXAM

Question 1

2 models of enzyme action

Answer 1

lock and key model

induced fit model

Question 2

define lock and key model

Answer 2

substrate has to fit perfectly in the active site

Question 3

define induced fit model

Answer 3

enzyme changes shape as it binds to the substrate

Question 4

suggest 2 reasons why we can’t just make our cells ever warmer to increase rate of reactions

Answer 4

• heating our cells would require a lot of energy
• higher temperatures damage our cells
• higher temperature speed up non useful reactions

Question 5

explain how increasing temperature causes an enzymes to denature

Answer 5

• high temperatures start to break the holding the enzymes together
• enzyme and it’s active site changes shape
• the enzymes active site will no longer be complementary to the substrate

Question 6

factors that affect enzymes

Answer 6

• after 37 degrees Celsius most enzymes start to change (denature)
  active site of enzymes changes too so the substrate doesn’t fit active site
  optimum temperature= optimum rate of enzymes
• pH
  optimum pH depends on what part of the body the enzyme works in
  most enzymes work best at pH of 7
  in stomach the enzymes work best at a pH of 2

Question 7

how do you figure out the rate of reaction

Answer 7

rate of reaction = how much a product or reactant changes by/ time it took change

Question 8

1. what enzyme is starch broken down by
2. where is this enzyme found in the body
3. what product is formed after starch is broken down

Answer 8

1. amylase
2. salivary glands, pancreas, small intestine
3. simple sugars
   maltose (into maltase into glucose)

Question 9

1. what enzyme are proteins broken down by
2. where is this found enzyme in the body
3. what product is formed after protein is broken down

Answer 9

1. protease
2. stomach, pancreas, small intestine
3. amino acid

Question 10

1. what enzyme are lipids broken down by
2. where is this enzyme found in the body
3. what products are formed after protein is broken down

Answer 10

1. lipase
2. pancreas, small intestine
3. glycerol and fatty acids

Question 11

how does bile help with the digestion of lipids

Answer 11

• bile emulsifies the lipids

- which increases the surface area for lipase enzymes to break them down

Question 12

what is the role of bile

Answer 12

bile is made in the liver and stored in the gall bladder
it is alkaline to neutralise the stomach acid
it emulsifies fat to form small droplets which increase the surface area.
the alkaline conditions and large surface area increase the rate of fat breakdown by lipase
helps to speed up the digestion of lipids (IS NOT AN ENZYME- bile emulsifies the lipids, increases the surface area of the lipid droplets and increases the rate of lipid breakdown by lipase)

Question 13

what is an enzyme

Answer 13

a biological catalyst that speeds up reactions

Question 14

what are proteins long chains of

Answer 14

proteins long chains of amino acids

Question 15

describe a lipid molecule

Answer 15

lipid molecule consists of a molecule of glycerol attached to 3 molecules of fatty acids

Question 16

for most human body enzymes what is optimum temperature

Answer 16

37 degrees Celsius