Enzymes UNIT 3 AOS 1

Question 1

Define enzyme?

Answer 1

a biological catalyst that increases the rate of reaction by lowering the activation energy

Question 2

Why are enzymes essential for life?

Answer 2

biochemical reactions of life would happen so slowly without them that the organisms would die

Question 3

What is activation energy?

Answer 3

the molecules in the reaction require a certain amount of energy for the reaction to procees. if the threshold of energy required is not met, the reaction will not proceed

Question 4

What is metabolism?

Answer 4

a sum of all chemical reactions in a living organism

Question 5

anabolic? (endergonic)

Answer 5

chemical reactions that build complicated molecules from simple ones, uses ATP

Question 6

catabolic? (exergonic)

Answer 6

chemical reactions that break down complicated molecules into simple ones, releases ATP

Question 7

what does this mean? “enzymes are highly specific”

Answer 7

an enzyme typically acts on one substrate only. This is due to the specific shape of the active site on the enzyme having to match the shape of the substrate molecule

Question 8

induces fit model?

Answer 8

• states that the substrate induces a change in shape of the enzymes active site as it binds to the enzyme, allowing the enzyme to snugly fit and wrap around the substrate.
• new bonds are formed between the substrate and active site. the bonds weaken making it easier to form the products

Question 9

how does temperature effect rate of reaction?

Answer 9

enzymes have an optimum temp of 37 degrees. If above the enzyme denatures, the active site changes shape, at low temp the enzyme becomes less active due to less kinetic energy. high the temperature more successful collisions, lower the temperature less successful collisions

Question 10

how does pH effect rate of reaction?

Answer 10

enzymes have an optimum pH at which they function best. a change in pH can denature the enzyme, causing the active site to change shape.

Question 11

how does enzyme concentration effect rate of reaction?

Answer 11

if the concentration of enzyme is increased so will the rate of reaction, however after a while the rate of reaction will plateau as a result of running out of substrate

Question 12

how does substrate concentration effect rate of reaction?

Answer 12

as substrate concentration increases so does rate of reaction, however then plateaus as a result of the saturation of enzymes due to too many substrates

Question 13

what is a cofactor?

Answer 13

non-protein that assists in enzyme activity. Can be inorganic or organic particles that are necessary for the function of particular enzymes

Question 14

what are coenzymes?

Answer 14

particular type of cofactor. very small organic molecules that are associated with particular enzymes and are essential for their activity.

Question 15

what are enzyme inhibitors?

Answer 15

certain chemicals that can block or alter the shape of the enzyme active site and stop their reaction

Question 16

what are the four types of inhibitors?

Answer 16

1. Competitive, irreversible: inhibitor blocks active site and doesn’t come out, enzyme can no longer function
2. Non-competitive, irreversible: inhibitor binds to somewhere else on the enzyme changing the shape of the active, inhibitor doesn’t leave and enzyme can’t work anymore
3. Competitive, reversible: inhibitor blocks active site but eventually leaves so enzyme works again
4. Non-competitive, reversible: inhibitor binds somewhere else on the enzyme, making it non functional, however leaves making the enzyme re-functional

Question 17

exergonic reaction?

Answer 17

have a net release of energy to its surroundings. the energy of the product is less than the reactants

Question 18

example of an exergonic reaction?

Answer 18

cellular respiration - organic molecules are broken down to release energy, occurs in autotrophs and heterotrophs

Question 19

endergonic reaction?

Answer 19

absorb energy from their surroundings, the energy of the products is greater than the energy of the reactants.

Question 20

example of endergonic reaction?

Answer 20

photosynthesis - complex compounds are manufactured from carbon dioxide and water, occurs in autotrophs

Question 21

what structure are enzymes?

Answer 21

protein molecules with a 3D tertiary structure, however sometimes have secondary structures

Question 22

how do enzyme catalyse a reaction?

Answer 22

provide a favourable environment for the subtrates to convert to products.

Question 23

where do cofactors and coenzymes come from?

Answer 23

many of these come from our diet, which is why we need small amounts of vitamins and minerals

Question 24

what is feedback inhibition?

Answer 24

occurs when the end product of a reaction interferes with the enzyme that helped produce it. The enzyme then changes its shape and can’t catalyze the reaction anymore

Question 25

how are enzymes involved in metabolic pathways?

Answer 25

chemical reactions involve hundreds of enzymes working in chains, where the product of the reaction is the substrate for the next enzyme. these chains are called metabolic pathways

Question 26

what are the four steps in enzyme catalysing?

Answer 26

1. the enzyme specific to the substrate moves into position
2. enzyme-substrate complex is formed
3. substrate snuggled into active site
4. products separated and enzymes resume original shape

Question 27

why can enzymes be used over and over again?

Answer 27

enzymes are not used up in the reacting and they remain the same at the end of the reaction, although they may be altered temporaily

Question 28

how do enzymes lower activation energy?

Answer 28

Enzymes provide a perfect environment for a substrate to bond too. Enzymes change the shape of the substrate, putting pressure on the bonds. This reduces the amount of activation energy required and therefore the reaction can take place more easier

Question 29

hydrolysis reaction?

Answer 29

involved breaking down of polymers and adding a water molecule. an example of catabolism

Question 30

dehydration reaction?

Answer 30

involved the adding of sub-units and removing a water molecule. an example of anabolism

Question 31

Rational drug design?

Answer 31

the development of a drug that specifically inhibits the active site of an enzyme, preventing a disease/virus from leaving te