Enzymes

Question 1

What type of proteins are enzymes?

Answer 1

Globular proteins

Question 2

What are enzymes?

Answer 2

Biological catalysts that speed up the ROR while remaining chemically unchanged

Question 3

What does intracellular mean?

Answer 3

Enzymes are produced and function inside the cell

Question 4

What does extracellular mean?

Answer 4

Secreted by cels and catalyse reactions outside cells

Question 5

What is an example of extracellular enzymes?

Answer 5

Digestive enzymes in the gut

Question 6

What happens at the active site?

Answer 6

The substrate binds

Question 7

What type of protein are enzymes?

Answer 7

Globular proteins

Question 8

What is an example of an intracellular enzyme?

Answer 8

Catalase

Question 9

What does catalase do?

Answer 9

Converts hydrogen peroxide into water and oxygen- preventing damage to cells or tissues

Question 10

What is an example of an extracellular enzyme?

Answer 10

Amylase

Question 11

What does amylase do?

Answer 11

Carbohydrate digestion- hydrolyses starch into simple sugars

Question 12

Why is digestion usually carried out by extracellular enzymes?

Answer 12

The macromolecules being digested are too large to enter the cell

Question 13

Where is amylase secreted from?

Answer 13

The salivary glands and the pancreas for the digestion of starch in the mouth and small intestine

Question 14

What is the definition of an enzyme?

Answer 14

Tertiary proteins that catalyse reactions by providing an alternative pathway with a lower Ea by the orientation of substrates

Question 15

What is the shape of the active site determined by?

Answer 15

The sequence of the amino acids in the primary structure and the R groups- the folding into the secondary and tertiary structure

Question 16

Lock and key theory?

Answer 16

Enzyme active site is a fixed shape
Random collisions between substrate and enzyme- forms ESC
Once ESC has formed, the substrate distorts in shape (lowering the Ea), the products are released and the active site is empty- can be reused again

Question 17

Lock and key theory?

Answer 17

Enzyme active site is a fixed shape
Random collisions between substrate and enzyme- forms ESC
Once ESC has formed, the substrate distorts in shape (lowering the Ea), the products are released and the active site is empty- can be reused again

Question 18

Induced fit theory?

Answer 18

Active site is induced (changes shape) to mould around the substrate
Puts strain on the bonds and weakens them- therefore lower Ea for the reaction to occur
Products are formed and released- the active site reverts back to its original shape

Question 19

Temperature?

Answer 19

Too low- not enough KE for successful collisions- less ESC’s
Too high- enzyme denatures- AS changes shape- no ESC’s formed
The bonds holding the AA in the 3D tertiary structure in the AS are broken- AS changes shaped

Question 20

PH?

Answer 20

Enzyme will denature
Too high- too many H+ ions
Too low= too many OH- ions
Fewer ESC’s- decreased ROR
Interfere with the charges on the AA in the AS— the hydrogen and ionic bonds will break

Question 21

Substrate concentration?

Answer 21

At the low concentration, the substrate conc is the limiting factor
Fewer substrate molecules are available to collide with the enzyme- fewer ESC’s- decreased ROR
When the graph plateaus- the increased substrate concentration- the enzyme concentration is the new limiting factor- the AS becomes saturates- the reaction cannot occur any faster

Question 22

Enzyme conc?

Answer 22

Empty AS due to insufficient substrate- more enzyme than substrate- not enough substrate to collide with the AS

Question 23

Competitive- what shape is the inhibitor?

Answer 23

The same or very similar tothe substrate- therefore it is complementary and can bind to the AS

Question 24

What does the competitive inhibitor prevent?

Answer 24

The substrate from binding and the reaction from occurring

Question 25

What will happen if more substrate is added to a competitive inhibitor?

Answer 25

This will out-compete the inhibitor- knocking them out of the AS

Question 26

Where do non-competitive inhibitors bind to the enzyme at?

Answer 26

The allosteric site

Question 27

What does the non-competitive inhibitor cause to the active site?

Answer 27

To change shape- the substrate can no longer bind (regardless of how much substrate is added)

Question 28

What do non-competitive inhibitors cause to the structure of the enzyme?

Answer 28

Causes the 3D (tertiary) structure of the enzyme to change shape- fewer ESC’s formed