Chapter 5: Enzymes

Question 1

Alimentary canal

Answer 1

the part of the digestive system through which food passes as it moves from the mouth to the anus.

Question 2

Enzymes

Answer 2

Proteins that are involved in all metabolic reactions and are not changed by the reaction.

Question 3

Substrate

Answer 3

the substance that an enzyme causes to react

Question 4

Complementary

Answer 4

with a perfect mirror-image shape.

Question 5

Active site

Answer 5

the part of an enzyme molecule to which the substrate temporarily binds.

Question 6

Buffer Solution

Answer 6

A liquid that has a known pH and that keeps that pH steady all the time.

Question 7

Why are enzymes important? (2)

Answer 7

-Without enzymes the reactions would take place very slowly or not at all.
-Enzymes ensure that the rates of chemical reactions are great enough to sustain life.

Question 8

How are enzymes produced?
(4)

Answer 8

-They are produced in the cells based on the instructions that are carried in the cell genome.
-The enzymes are therefore made up of amino acids,
-Most of them have 100 to 1000 amino acids.
-The amino acids are joined together in long chain which is then Folded to produce a unique structure.

Question 9

Important- (6)

Answer 9

-Enzymes are also found in the plants, for example in germinating seeds they digest the food stores for the growing seedling.
-Many seeds contain stores of starch.
-As the seed slacks up water, the enzyme amylase becomes active.
-Amylase catalyses the reaction in which starch breaks down to maltose.
-Starch is insoluble, but maltose is soluble so it can easily be transported to the embryo in the seed.
-The embryo uses it to provide energy for growth.

Question 10

Enzymes that breakdown substances (9)

Answer 10

Catalase
Amylase
Maltose
Protease
Lipase
Sucrase
Pepsin
Carbohydrases
Lactase

Question 11

Enzyme that converts

Answer 11

Isomerase-
the enzyme that catalyses the conversion of glucose into fructose.

Question 12

Enzymes that build substances (2)

Answer 12

Protease
Phosphorylase

Question 13

Catalase

Answer 13

the enzyme that catalyses the breakdown hydro peroxide to water and oxygen.

Question 14

Amylase

Answer 14

the enzyme that catalyses the breakdown starch to maltose

Question 15

Maltose

Answer 15

the enzyme that catalyses the breaks down maltose to sucrose and glucose

Question 16

Protease

Answer 16

the enzyme that catalyses the breaks down proteins to amino acids.

Question 17

Lipase

Answer 17

the enzyme that catalyses the breakdown lipids to glycerol and fatty acids.

Question 18

Sucrase

Answer 18

the enzyme that catalyses the breaks down sucrose to fructose and glucose.

Question 19

Pepsin

Answer 19

the enzyme that catalyses the breaks down proteins to peptides.

Question 20

Carbohydrases

Answer 20

the enzyme that catalyses the breaks down carbohydrates.

Question 21

Lactase

Answer 21

the enzyme that catalyses the breaks down lactose to galactose and fructose.

Question 22

Protease 2

Answer 22

the enzyme that help to make large molecules (proteins) from small molecules (amino acids).

Question 23

Phosphorylase

Answer 23

the enzyme that helps to make large molecules (starch) from small molecules (glucose).

Question 24

Why is catalase important? (3)

Answer 24

-It is necessary because hydrogen peroxide is produced by many of the chemical reactions which take place inside cells.
-Hydrogen peroxide is a very dangerous substance that must be broken down immediately.
-It is the fastest enzyme known, it can break down 44 million hydrogen peroxide molecules in one second.

Question 25

Lock and Key Mechanism (5)

Answer 25

-All enzymes have a particularly shaped dent, called the active site where the reaction takes place.
-The enzyme is very specifically shaped for the reaction they catalyze.
-It works by letting the substrate (with a complementary shape to the enzyme’s shape) temporarily bind into the enzyme’s active site and form the enzyme-substrate complex.
-Here the substrate is changed into new substances called products.
-The products leave the active site and the enzyme is ready to receive another substrate

Question 26

What is enzyme specificity? (2)

Answer 26

-Each enzyme can only catalyse reactions with one type of substrate.
-This is described as enzyme specificity.

Question 27

Factors effecting Enzyme Activity
Temperature
0 degrees
(4)

Answer 27

-There is no activity here.
-low temperatures causes less kinetic energy in the molecules
-hence they move more slowly and the enzyme and substrates collide less frequently.
-They rarely enter the active site and only a few substrates are converted into products.

Question 28

Temperature increases
5+ 3

Answer 28

(Graph shows increase in activity)

Highest point here is the optimum.
-As temperature increases, kinetic energy increases,
-Causing the enzymes and substrates to move faster
-More effective collisions are frequent.
-Thus more substrate molecules collide into the active site and turn into products . -Optimum
Rate of Enzyme activity is fastest.

Question 29

After optimum
(5)

Answer 29

(Graph shows a decrease in activity)
-Kinetic energy causes the enzymes to be shaken apart.
-Molecules lose their shape and causes the active site to not be a true complementary to its substrate.
-Hence the substrate cannot fit into the disfigured active site,
-No enzyme substrate complex is formed and the products are not produced.
-The enzyme is said to be denatured.

Question 30

pH (3)

Answer 30

-the change in the pH also alters the shape of an enzyme.
-The optimum pH for an enzyme depends on where it normally works.
-For eg- the optimum pH for pepsin which is found in the stomach is around 2.

Question 31

Substrate Concentration (3)

Answer 31

-As the amount of substrate increases the rate of reaction increases
-however once all the active sites of the enzymes are occupied,
-The rate of reaction reaches a constant.

Question 32

Enzyme Concentration

Answer 32

The rate of reaction increase with an increase in the concentration of enzymes.

Question 33

Lipase (pancreas)

Answer 33

8.0

Question 34

Lipase (stomach)

Answer 34

4.0 - 5.0

Question 35

Lipase (castor oil)

Answer 35

4.7

Question 36

Pepsin

Answer 36

2

Question 37

Trypsin

Answer 37

7.8 - 8.7

Question 38

Urease

Answer 38

7.0

Question 39

Maltase

Answer 39

6.1 - 6.8

Question 40

Amylase (pancreas)

Answer 40

6.7 - 7.0

Question 41

Amylase (malt)

Answer 41

4.6 - 5.2

Question 42

Catalase

Answer 42

7.0