enzymes

Question 1

catalyst

Answer 1

a substance that can speed up a chemical reaction without itself being chemically changed at the end of the reaction

Question 2

catalyse

Answer 2

the process of speeding up the rate of a chemical reaction and the catalyst itself remaining chemically unchanged at the end of the reaction

Question 3

enzymes

Answer 3

proteins that function as biological catalysts

Question 4

activation energy

Answer 4

the energy needed to start a chemical reaction

Question 5

anabolic reaction

Answer 5

reaction that build up complex substances

Question 6

catabolic reaction

Answer 6

reaction that break down complex substances

Question 7

lock and key hypothesis

Answer 7

-enzymes has a specific 3D shape with a depression called the active site
-only substrates with a complementary 3D shape can fit into the enzyme to form an enzyme-substrate complex
-enzyme is lock, substrate is key according to lock and key hypothesis
-when substrate is attached to the active site, a chemical reaction occurs and the substrate is converted to products
-products leave active site, enzyme remains unchanged and can catalyse another reaction

Question 8

characterises of enzymes

Answer 8

-speeds up chemical reactions; lower Ea
-specific in action; active site
-required in minute amounts; remain chemically unchanged and can be used again
-affected by temperature and pH

Question 9

denature

Answer 9

change in 3D structure of an enzyme or any other soluble protein caused by heat or chemicals such as acids or alkalis

Question 10

describe enzyme temperature graph

Answer 10

-enzymes are less active at low temperature; KE of enzyme and substrate is low, frequency of effective collision is low
-as temperature increase, rate of enzyme reaction increases; more KE
-optimum temperature where enzyme is most active [40-45 for most human enzymes]
-rapid decrease in rate of enzyme reaction; active site begins to denature, no longer complementary
-no enzyme reaction; all enzymes have been denatured

Question 11

describe enzyme pH graph

Answer 11

-enzymes are less active at low pH; KE of enzyme and substrate is low, frequency of effective collision is low
-as pH increase, rate of enzyme reaction increases; more KE
-optimum pH where enzyme is most active; most KE
-rapid decrease in rate of enzyme reaction; excessive KE disrupts bond within the enzyme, active site begins to denature, no longer complementary
-no enzyme reaction; all enzymes have been denatured

Question 12

optimum pH for protease in stomach/pepsin

Answer 12

1

Question 13

optimum pH for amylase

Answer 13

6

Question 14

optimum pH for protease in small intestine/trypsin

Answer 14

7.5

Question 15

conditions that can affect rate of enzyme reaction

Answer 15

-pH
-temperature
-concentration