module 2 - 2.1.4 - enzymes

Question 1

What are enzymes?

Answer 1

-globular proteins
-interact with substrates to make te reaction happen faster

Question 2

meaning of activation energy?

Answer 2

the amount of energy needed to start a reaction

Question 3

meaning of active site?

Answer 3

an area in the tertiary structure that has a specific shape that is complementary to the substrate.

Question 4

What is the lock and key hypothesis?

Answer 4

1.only the specific substrate will fit into the complementary active site
2.this forms an enzyme-substrate complex
3.the substrate then reacts and forms products making a enzyme-product complex
4,products are then released leaving the enzyme unchanged

Question 5

How does the enzyme hold the substrate to increase the rate of reaction?

Answer 5

• held so the right atom groups are close enough to react
  -R groups of the active site will interact with the substrate forming temporary bonds

Question 6

What is the induced fit hypothesis?

Answer 6

1, substrate enters active site with a weak interaction
2, forms an enzyme substrate complex
3,the weak interactions cause a change in the tertiary structure of the enzyme , this puts a strain on the substrates
4,this lowers the activation energy and products are released

Question 7

How do enzymes increase the rate of reaction?

Answer 7

they lower the activation energy

Question 8

What are intracellular enzymes?

Answer 8

enzymes that work in the cell

Question 9

Two examples of intracellular enzymes?

Answer 9

1. lactase= breaks down lactose into glucose and galactose

2.catalase= breaks hydrogen peroxide down into water and oxygen = found in plants and humans

Question 10

Extracellular enzymes?

Answer 10

enzymes that work outside the cell that made them

Question 11

Why are extracellular enzymes needed?

Answer 11

nutrients needs to enter cells but are too large so need to be broken down.
enzymes are released from the cell to break the nutrients down

Question 12

Examples of extracellular enzymes?

Answer 12

1. amylase= secreted by salivary glands, catalyses the hydrolysis of starch into maltose
   2.tryspin

Question 13

Factors that impact enzymes?

Answer 13

1. temperature
   2.PH
   3.enzyme concentration
2. substrate concentration

Question 14

What happens to the rate of reaction with enzymes when the temperature increases?

Answer 14

1,increases the kinetic energy of the particles
2,this makes the particles move more and collide more often
3,this will mean there are more successful collisions of substrates and enzymes
4,= an increased rate of reaction

Question 15

What does temperature coefficient Q10 mean?

Answer 15

a measure of how much the rate of reaction increases with a 10 degree raise in temperature

Question 15

What is denaturing?

Answer 15

1,at a high temp the bonds holding the protein (enzyme) together vibrate more
2,as the temp increases the bonds strain and eventually break
3, the breaking of the bonds change the shape of the tertiary structure
4,it is then denatured

Question 16

optimum temperature meaning?

Answer 16

the temperature where the enzyme has the highest rate of reaction

after the optimum temp enzyme denatures and rate of reaction decreases rapidly

Question 17

What are enzymes like that are meant to be in cold temps?

Answer 17

• have more flexible structures
  = less stable
  -small temp changes can denature them

Question 18

What are enzymes like that are meant to be in hot temps?

Answer 18

=more stable
=more resistant to change of temps so less likely to denature

Question 19

What happens to the enzyme when the PH is not at the optimum?

Answer 19

active site is likely to change shape
=reduces rate of reaction

Question 20

What happens to rate of reaction if the conc of substrates or enzymes increases?

Answer 20

more successful collisions between the active sites and substrates so increase of rate of reaction

Question 21

What is the role of inhibitors?

Answer 21

To slow down a reaction so excess product is not made

Question 22

What are the two types of inhibitors?

Answer 22

1.competitive
2. non-competitive

Question 23

How does competitive inhibition work?

Answer 23

1.a similar shaped molecule to the active sire can fit into the active site
2.blocks the substrate from attaching to the active site
3.enzyme can not catalyse
4.substrates and inhibitors compete for the active site
5.reduce amount of substrates attaching to the active sire
=decrease in rate of reaction

Question 24

How do competitive inhibitors impact the rate of reaction?

Answer 24

=decreases rate of reaction

Question 25

Examples of competitive inhibitors?

Answer 25

-statins =reduces blood cholesterol levels
-aspirin=reduces chemical for pain

Question 26

How does non-competitive inhibition work?

Answer 26

1.the inhibitor binds to somewhere else other than the active site making a allosteric site
2.this causes tertiary of the enzyme to change changing the shape of the active site
3.substrates no longer complementary so cannot bind

Question 27

How do non-competitive inhibitors change the rate of reaction?

Answer 27

=decreases the rate of reaction as less available active sites

Question 28

examples of non-competitive inhibitors?

Answer 28

1.insectisides= needed for nerve impulses
2.proton pump= reduces production of excess acid in the stomach

Question 29

end - product inhibition?

Answer 29

This is when the products of an enzyme inhibit the enzyme that produced them

Question 30

Roles of cofactors?

Answer 30

transfer atoms/groups from one reaction to another by a pathway

Question 31

Whats a coenzyme?

Answer 31

when a cofactor is an organic molecule

Question 32

How are inorganic cofactors obtained?

Answer 32

via the diet through minerals
=iron,calcium,chloride

Question 33

How are coenzymes obtained?

Answer 33

via vitamins in the diet
=vitamin B3 , vitamin B5

Question 34

What are prosthetic groups?

Answer 34

=cofactors
=required for certain enzymes to carry out catalytic functions

Question 35

Are cofactors essential?

Answer 35

no

Question 36

are coenzymes essential?

Answer 36

yes

Question 37

whats a precursor activator?

Answer 37

an inactive enzyme

Question 38

What do precursor activators do?

Answer 38

temporarily bind to an enzyme and alter its active site