1.7 +1.8 + 1.9 Enzymes + factors that affect enzyme action

Question 1

definition of enzyme:

Answer 1

a biological catalyst that speeds up chemical reactions without being used up

Question 2

how does a catalyst speed up rate of reaction?

Answer 2

It provides a lower activation energy pathway, allowing the chemical reaction to occur with less energy

Question 3

why are enzymes important to mammals?

Answer 3

Mammals are usually not hot enough to be able to provide the energy required for chemical reactions
And enzymes provide a lower activation energy, allowing chemical reactions to occur even if there’s less energy available

Question 4

what is the active site?

Answer 4

where the substrate binds

Question 5

what determines the shape of the enzyme?

Answer 5

the highly specific tertiary structure of the protein

Question 6

enzyme induced fit theory:

Answer 6

• shape of the substrate is complementary to the active site of the enzyme
• when the substrate binds to the enzyme, it forms an enzyme-substrate complex
• this causes the active site to change slightly by induced fit
• increasing rate of reaction

Question 7

how do enzymes help in condensation reactions?

Answer 7

• in the active site the molecules are physically held close together
• allowing new chemical bonds to be formed more easily
• molecules are physically close together, less repulsion between molecules
• activation energy reduced

Question 8

how do enzymes help in hydrolysis reactions?

Answer 8

• in the active site, strain is put on the chemical bonds in the substrate molecule
• meaning bonds are more easily broken
• activation energy is reduced

Question 9

factors that affect enzyme reaction:

Answer 9

high temperature
pH
substrate concentration
enzyme concentration

Question 10

how does temperature increase enzyme action?

Answer 10

increase in temperature
= increase in molecules KE
= more successful collisions between substrate and active site
= more ES complexes made
= increase rate of reaction

Question 11

what happens to enzymes when the temperature goes past optimum?

Answer 11

further increase of temperature
= enzymes vibrate
= causing bonds to break in the tertiary structure
= shape of active site changes (no longer complimentary to substrate)
= no ES complexes made
= decrease in rate of reaction

Question 12

how does enzyme concentration increase enzyme action?

Answer 12

increase number of enzymes
= increase number of active sites
= increase rate of reaction

then substrate is the limiting factor

Question 13

how does substrate concentration increase enzyme action?

Answer 13

increase substrate concentration
= more E.S complexes
= increase rate of reaction

enzyme concentration is the limiting factor
= no free active sites
- all enzymes are involved in E.S complexes

Question 14

enzyme inhibitors:

Answer 14

molecules that bind to an enzyme and stop it form functioning by stopping E.S complexes from forming

Question 15

competitive inhibitors:

Answer 15

molecules that compete for the active site and have similar shape to substrate

Question 16

non-competitive inhibitors:

Answer 16

bind to the enzyme away from the active site (to the allosteric site)
causes site to change shape
no longer able to bind to active site
enzyme will be non functional

Question 17

comp vs non-comp inhibitors

Answer 17

comp inhibitors can be overcome by an increase in substrate concentration
however
non-comp inhibitors cannot, as they permanently change the active site