Enzymes

Question 1

what are enzymes?

Answer 1

biological catalyst which speed up the rate of chemical reactions without lowering the activation energy

Question 2

Why are enzymes different shapes?

Answer 2

because it is made from a unique sequence of amino acids

Question 3

Why is the shape of the enzyme important?

Answer 3

vital for its function

Question 4

what is the active site?

Answer 4

part of an enzyme where molecules (substrate) can fit during a reaction

Question 5

if the shape of the active site is changed..?

Answer 5

Then the enzyme will not work as the enzyme will be denatured

Question 6

what type of proteins are enzymes?

Answer 6

globular proteins, tiertiary structure

Question 7

what is the activation energy?

Answer 7

the minimum amount of energy required for a reaction to start

Question 8

other functions of proteins?

Answer 8

biological catalysts, control the rate of metabolic reactions

Question 9

explain enzyme activity using the lock and key model?

Answer 9

an enzyme has a specific active site. the substrate will have a complimentary shape and size to the enzymes active site and fit in/binds to the enzymes active site. The enzymes active site will break down the substrate into smaller molecules.

Question 10

limitations of the lock and key model?

Answer 10

Enzymes are not a fixed shape like a ‘lock’. It explains how other molecule affect enzyme action (by binding away from the active site). It explains how activation energy is lowered (by
changing shape the enzyme puts a strain on the
substrate molecule and distorts the bonds)

Question 11

explain enzyme activity using the induced fit model?

Answer 11

the enzyme has a specific active site. the substrate will be complimentary and fit into the active site.This is the inital binding. then the enzyme changes shape and the substrate will fit more closely and strongly to the active site. This is called the induced fit. and the enzyme will break down the substrate then release the products.

Question 12

factors effecting the rate of enzyme-controlled reactions?

Answer 12

temperature, pH, enzyme concentration, substrate concentration and inhibitors

Question 13

Explain how temperature effects the rate of reaction?

Answer 13

increasing temperature increases the kinetic energy of the molecule so there is faster movement. Collisions between enzyme and substrate or more frequent and energetic the rate of reaction increases.

Question 14

explain how temperature effects the rate of reaction? (high temperature)

Answer 14

The enzyme molecule vibrates so much that the weak bonds maintaining the tertiary structure are broken hydrogen and ionic bonds cannot reform so the shape of the molecule changes and the active site can no longer function. It is denatured

Question 15

explain how pH effects the rate of reaction?

Answer 15

Changing pH alters the amount of hydrogen and hydroxyl ions these are attracted to the charges on the amino acids in the polypeptide to strong bonds altering the enzyme shape

Question 16

what pH does intracellular enzymes work best in?

Answer 16

7.3-7.45

Question 17

what pH do extracellular enzymes work best in?

Answer 17

at extreme pH e.g pepsin =pH2

Question 18

what is the pH of chymotrypsin?

Answer 18

pH8

Question 19

explain how substrate concentration effects the rate of reaction?

Answer 19

As substrate concentration increases so does the rate of reaction as more collisions can occur between substrate and enzyme until all the active sites of failed. when all the artists sites have filled the rate is limited by enzyme concentration and can only be increase if more enzyme is added

Question 20

explain how enzyme concentration effects the rate of reaction?

Answer 20

As enzyme concentration increases so does the rate of reaction as more collisions can occur between substrate and enzyme until all the substrate is used. there are many enzymes with empty active sites but the substrate concentration is the limiting factor.

Question 21

what are enzyme inhabitors?

Answer 21

slow down or stop enzyme reactions

Question 22

explain competitive enzyme inhibition on the rate of reaction ?

Answer 22

• the 3d tiertiary structure of proteins gives enzymes the specific shape of an active site. - competitive inhibitors are similar in shape to the substrate and bind to enzymes active sites. this prevents the substrate from binding to the active site and no enzyme substare complexes form. instaed a enzyme-inhibitor complex is formed. this decreases the ROR. The ROR increases with a hgher substrate concentration

Question 23

explain non-competitive enzyme inhibition on the rate of reaction?

Answer 23

the 3D tertiary structure of proteins give enzymes the specific shape of an active. the enzyme also has another active site away from the original called the allosteric site. the non-competitive inhibitor is not similar in shape to the substrate and binds away from the from the active site to the allosteric site. this changes the shape of the active site so the substrate cannot bind to the active site so no enzyme-substrate complexes are formed. this decreases the rate of reaction.

Question 24

what are the uses of inhibitors?

Answer 24

many enzyme inhibitors are natural poisons so inhibitors in venom can irreversibly block enzymes which cause death and paralysis

Question 25

ph caluclations?

Answer 25

pH = -log[H+]

Question 26

what is the definition of pH?

Answer 26

pH is equal to the negative log of the hydrogen ion concentration of a solution