2.1.4 Enzymes

Question 1

What are the properties about enzymes?

Answer 1

• tertiary structure
• specific
• enzyme structure is affected by high temps and extreme pH

Question 2

What are the similarities between intracellular and extracellular enzymes?

Answer 2

both made within the cell

Question 2

What is an enzyme?

Answer 2

biological catalysts that are used in metabolic reactions; lower the activation energy; not used up in the reaction

Question 3

What are the differences between intracellular and extracellular enzymes?

Answer 3

extracellular = released out of the cell via exocytosis as they don’t work inside the cell

Question 4

What is an example of intracellular enzymes?

Answer 4

catalase - breakdown hydrogen peroxide into oxygen

Question 5

What is an example of extracellular enzymes?

Answer 5

amylase = breakdown carbohydrates
trypsin = breakdown proteins

Question 6

What is the lock and key hypothesis?

Answer 6

the enzyme is the lock and the substrate is the key
in order for the substrate to bind to the active site of the enzyme, it must have the correct specific and complementary shape to ‘fit’ the active site for to for a ESC.

Question 7

What is the induced for hypothesis?

Answer 7

when a substrate binds to the active site of the enzyme, the active site also changes shape slightly

Question 8

What is the effect of temperature on enzyme activity?

Answer 8

As the temp increases, the enzyme and substrate gain kinetic energy; there are more successful collisions between the substrate and active site ; there are more ESC

Question 9

What occurs after the optimum temperature on enzyme activity?

Answer 9

Due to gaining a lot of kinetic energy the molecules in the enzyme move more; and this breaks the hydrogen and ionic bonds; denatures the enzyme; the active site is no longer complementary or specific in shape to the substrate; the tertiary structure of the enzyme changes; fewer ESC formed

Question 10

What is the effect of low pH on enzyme activity?

Answer 10

at a low pH the H+ attract the negative R groups in the hydrogen and ionic bonds; causing the hydrogen and ionic bonds to break; this changes the tertiary structure of the enzyme; the active site is no longer complementary or specific in shape to substrate; fewer ESC formed

Question 11

What is the effect of substrate concentration on enzyme activity?

Answer 11

as the substrate concentration increases there are more successful collisions between active site and substrate; there are more ESC formed; until all the active site are saturated; enzyme concentration becomes limiting factor

Question 12

What is a coenzyme?

Answer 12

• organic molecule
• has a specific and complementary shape to enzymes active site
• needed to activate the enzyme
• not permanently bound to enzyme
• involved in the reaction
• as number of coenzymes increase, rate of reaction increases
• e.g NAD and FAD

Question 13

What are prosthetic groups?

Answer 13

non-protein group permanently bound to the protein = aids function

Question 13

What is a co-factor?

Answer 13

• inorganic molecule
• permanently bound to enzyme
• helps the enzyme form a specific and complementary shape to substrate
• doesn’t take part in the reaction

Question 14

Give an example of a co-factor and where it is used?

Answer 14

Cl- ion is a cofactor for amylase

Question 15

Give an example of a prosthetic group and where it is found?

Answer 15

Zn2+ as a prosthetic group for carbonic anhydrase

Question 16

Give example of a source of coenzymes?

Answer 16

Vitamins

Question 17

What are competitive inhibitors?

Answer 17

substrate competes with inhibitor;
both the substrate and the inhibitor have a specific and complementary shape to the active site;
there will be fewer ESC’s;
more substrate reduces the chance of the inhibitor getting into the active site

Question 18

What are non-competitive inhibitors?

Answer 18

the inhibitor fits into an allosteric site;
this changes the shape of the active site;
substrate is no longer complementary to the active site;
fewer ESC’s formed;

Question 19

What is end product inhibition?

Answer 19

the end product binds to the enzymes allosteric site and changing the shape of the active site preventing it from binding to any more substrate

Question 20

What are inactive precursors?

Answer 20

an inactive enzyme that is made active until a change occurs e.g transcription factor