Enzymes

Question 1

What is a catalyst?

Answer 1

A substance that increases the rate of a chemical reaction but does not get used up/changed/altered

Question 2

What is an enzyme?

Answer 2

A protein molecule made by cells and acts as a catalyst

Question 3

How are enzymes made?

Answer 3

By protein Synthesis

Question 4

What are intracellular enzymes?

Answer 4

Only work inside of cells

Question 5

What are extracellular enzymes?

Answer 5

Only work outside of cells (either in environment or in lumen)

Question 6

What is specificity?

Answer 6

The relationship between an enzyme and the only type of molecule that fits into its active site

Question 7

What are active sites made of?

Answer 7

A few amino acids within a polypeptide

Question 8

What two things do eynzymes catalyse?

Answer 8

The breakdown and buildup of biological molecules

Question 9

What three things can you infer from the name of an enzyme?

Answer 9

First part is the substrate, second is the reaction, and should end in ‘ase’

Question 10

What do we know about carbohydrase?

Answer 10

The substrate is carbohydrates, the reaction is hydrolysis, and it is an enzyme (its a hydrolase enzyme - catalyses hydrolysis)

Question 11

If an enzyme is less specific?

Answer 11

Can catalyse a number of reactions of the same type

Question 12

How specific is subtilisin - breaks peptide bonds between any AA?

Answer 12

Not very

Question 13

How specific are trypsin and chymotrypsin?

Answer 13

Quite, only breaks bonds between certain AA, chymotrypsin (more specific)

Question 14

What is an enzyme-substrate complex?

Answer 14

Complex formed when a substrate fits into an enzymes active site

Question 15

Lock and key hypothesis?

Answer 15

Active site is complementary in shape to the substrate like a lock (enzyme) and key (substrate)

Question 16

Enzyme-product complex?

Answer 16

Complex formed in the active site after the reaction is complete but before product(s) leaves

Question 17

Induced-fit hypothesis?

Answer 17

Active site of an enzyme changes shape during binding of a substrate molecule, putting a strain on the substrate molecule and contributing to the reaction

Question 18

Activation energy?

Answer 18

Energy needed to overcome the energy barrier to allow a reaction to occur

Question 19

How do enzymes effect the activation energy of a reaction?

Answer 19

Provide alternative pathway with a lower activation energy

Question 20

Model of activation energy?

Answer 20

Energy barrier is the hump at the top of a hill, AE is the energy needed to push a ball over the hump (EB) and down the hill (the reaction), with an enzyme the energy barrier and energy needed is decreased (smaller hump) m

Question 21

Investigating enzyme activity for milk protein solution with protease?

Answer 21

10cm3 of milk solution to tube 1, 10cm3 of protease to test tube 2, put both in 25 degrees water bath for 5 mins, mix together the two tubes, time how long it takes for cloudiness to disappear

Question 22

Rate of reaction?

Answer 22

1/time taken for substrate to disappear or product to to appear

Question 23

Why put enzyme and substrate both in bath separate?

Answer 23

To equilibrate them

Question 24

Optimum temp?

Answer 24

Temp when ROR is at max and a decrease or increase in temp will decrease the ROR

Question 25

Increase in temp?

Answer 25

Increase KE of molecules, mols move faster, chance of collisions is higher, more successful collisions occur = more product formed

Question 26

How do enzymes denature?

Answer 26

Molecules vibrate, increased KE and vibration strains the enzyme and weakens hydrogen and ionic bonds which hold the tertiary structure, once tertiary structure alters = active site is not complementary

Question 27

Temp coefficient?

Answer 27

Ratio between the ROR of two different temps for the same reaction (ROR at x + 10 degrees/ROR at x degrees =Q10)

Question 28

What is ph?

Answer 28

Concentration of H+ ions in a solution (A decrease of 1 PH is a x10 difference in H+ ions)

Question 29

How does ph effect enzymes?

Answer 29

Due to the active sites hydrogen bonds, a big change in H+ ions will break some of the AS bonds, enzyme can lose shape and get denatured also far away from neutral

Question 30

How does ph differ from temperature when denaturing enzymes?

Answer 30

Reversible

Question 31

When might PH cause a permanent denature?

Answer 31

When at extreme PH

Question 32

How does low substrate concentration effect ROR?

Answer 32

Few substrate molecules, fewer collisions, fewer enzyme substrate complex' formed

Question 33

How does high enzyme concentration effect the ROR?

Answer 33

More AS' available for substrates to fit in, more enzyme-substrate complexes form,

Question 34

What is an issue with increasing substrate or enzyme concentration?

Answer 34

At some point there will be a limiting factor (whichever is not being increased) where there is not enough of the other reactant to collide with, or it is at its max ROR at that temp/ph