Enzymes, uncertainty

Question 1

What are enzymes

what effects enzyme action

Answer 1

Biological catalysts and globular proteins

temperature and PH

Question 2

How do enzymes bind to substrates and what do they form

Answer 2

They bind to a complementary active site by colliding at the right speed and orientation and forms an
Enzyme substrate complex

Question 3

What leads to enzyme specificity

Answer 3

the tertiary structure (determines the active site)

specificity of an enzyme is a result of the complimentary nature

Question 4

What is a catabolic and an anabolic reaction

Answer 4

Catabolic = breakdown of complex molecules into simpler products e.g. respiration

anabolic = building of more complex molecules from simpler ones

Question 5

What is the induced fit model

Answer 5

-enzyme and substrate interact with each other
- The enzyme and its active site can change shape slightly as the substrate binds
- The changes in shape are called conformal changes
-Ensures an ideal binding arrangement
- Maximises ability to catalyse reactions

Question 6

how does temperature effect enzyme reaction

Answer 6

• Have specific optimum temperature
• Lower temperature - less kinetic energy - less enzyme substrate complexes formed - lower rate of reaction
• Higher temperature - Higher kinetic energy - more enzyme substrate complexes formed - higher rate of reaction
• if temp too high or too low bonds in the tertiary structure break changing it meaning the enzymes denature

Question 7

What goes on the X and Y axis of a graph

Answer 7

X = IV
Y = DV

Question 8

what is interpolation and extrapolate mean

Answer 8

interpolation- Reading of values in between existing data points
extrapolate - Going beyond the range of points to read values

Question 9

How do you work out the percentage error

Answer 9

percentage error=
(uncertainty/measured value) x 100

Question 10

How does pH affect enzyme action

Answer 10

• Enzymes have an optimum pH
• Hydrogen and ionic bonds holding together the tertiary structure can break
• Bellow and above optimum pH solutions with excess H+ ions (acids) and excess OH- ions (alkali) will cause bonds to break
• Alters the shape of the active site

Question 11

How can the pH be calculated be calculated if we know the H+ value

Answer 11

pH =
-log^10 (H+)

Question 12

What does a pH buffer do

Answer 12

inhibits the change of pH

Question 13

How does enzyme concentration effect enzyme action

Answer 13

• higher the enzyme concentration in a reaction, the greater number of active sites and likelihood of enzyme-substrate complex formation
• As long as there’s sufficient substrate available the rate of reaction will increase

Question 14

How does substrate concentration affect enzyme action

Answer 14

• More substrate molecules increase the likelihood of enzyme-substrate complexes forming
• if enzyme concentration remains fixed but the amount of substrate rises past a certain point, all available active sites will become saturated and any further increase of the substrate will not increase the rate of reaction
• When active sites of enzymes any added substrate will have no active site to bind too

Question 15

What do enzyme inhibitors do?

Answer 15

Enzyme activity can be reduced or stopped, temporarily by a reversible reaction

Question 16

What are the different types of enzyme inhibitors and explain what they do

Answer 16

competitive - Have a similar shape to the substrate, they compete with the substrate for the active site blocking it so substrates cannot bind and create ES- complexes

non-competitive - Inhibitors bind to the allosteric site altering the shape of the active site preventing a substrate form binding

Question 17

What do reversible inhibitors do

Answer 17

• can act as regulators in metabolic pathways because metabolic reactions b=must be tightly controlled and balanced
• Its controlled by using the end product of a ES-complex by it becoming a non competitive inhibitor

Question 18

What happens to a competitive and non-competitive inhibitor when the substrate concentration is increased?

Answer 18

. competitive - The rate of reaction will still increase. increasing the concentration of substrates will reverse the effects of the competitive inhibitor as the substrate will out-compete it for active sites
. non-competitive -Will not effect the rate of reaction. Substrates will still not be able to bind to the active site

Question 19

What happens if the concentration of inhibitors increases

Answer 19

Rate of reaction will decrease because less Es-complexes can be formed. If the concentration still continues to rise the reaction will stop completely