Factors Affecting Enzyme Activity

Question 1

What must happen for an enzyme to catalyse a reaction?

Answer 1

Must come into contact with the substrate, and the enzyme must have a complementary shape for the substrate.

Question 2

What factors can affect an enzymes complex structure?

Answer 2

pH and temperature.

Question 3

What can a change in pH and temperature cause for the enzyme?

Answer 3

A change in the shape of their active site. Enzymes are more likely to come into contact with the substrate if temperature and substrate concentration are increased.

Question 4

How can factors affecting enzyme action be investigated?

Answer 4

By measuring the rate of reaction they catalyse.

Question 5

How does temperature affect enzyme activity?

Answer 5

Increasing the temperature increases the KE of the particles. They they move faster and collide more frequently.

Question 6

In an enzyme controlled reaction, what will an increase in temperature result in?

Answer 6

More frequent successful collisions between substrate and enzyme which lead to an increase in the ROR.

Question 7

What is the temperature Coefficient (Q10) of a reaction?

Answer 7

A measure of how much the ROR increases with a 10 degree rise in temperature.

Question 8

In enzyme controlled reaction, Q10 often takes 2. What does this mean?

Answer 8

The ROR doubles with a 10 degree temperature increase.

Question 9

How does Denaturation occur from temperature?

Answer 9

-At higher temperatures, bonds vibrate more.
-As temperature increases, vibrations increase until bonds strain and break.
-Results in a change in the precise tertiary structure of the protein.

Question 10

How does denaturation effect the enzyme?

Answer 10

-Active site changes shape, no longer complementary to substrate.
-Enzyme will no longer function as a catalyst.

Question 11

What is the optimum temperature?

Answer 11

The temperature at which the enzyme has the highest rate of activity. It can vary significantly.

Question 12

What is the optimum temperature for human body enzymes?

Answer 12

Around 40 degrees

Question 13

What is the optimum temperature for Thermophilic Bacteria? (found in hot springs)

Answer 13

70 degrees

Question 14

What is the optimum temperature for Psychrophilic Organisms? (live in cold regions)

Answer 14

Below 5 degrees

Question 15

What happens once the enzyme has denatured above optimum temperature? And what type of change does it have to be?

Answer 15

The decrease in rate of reaction is rapid. Only needs to be a small change in active site to no longer be complementary.

Question 16

Why is loss of activity pretty abrupt?

Answer 16

Happens to all enzyme molecules around the same temperature.

Question 17

What happens with regards to the optimum temperature in an enzyme-controlled reaction?

Answer 17

Temperature coefficient (Q10) no longer applies as enzymes have denatured.

Question 18

Why is the decrease in rate of reaction below optimum temperature less rapid?

Answer 18

Enzymes haven’t denatured, just less active.

Question 19

What happens in Extreme cold environments?

Answer 19

Enzymes controlling metabolic activities of organisms need to be adapted.

Question 20

What are some examples of Extreme Cold environments?

Answer 20

Deep Oceans, High altitudes, Polar regions

Question 21

What are some examples of the adaptations in Extreme Cold Environments?

Answer 21

-More flexible structures, less stable than enzymes that work at higher temperatures.
-Small temp changes will denature them.

Question 22

What are Thermophiles adapted for?

Answer 22

Extreme hot environments

Question 23

What are some examples of Thermophilic environments?

Answer 23

Hot springs, deep sea hydrothermal vents.

Question 24

What are some examples of adaptations for Thermophilic environments?

Answer 24

-Enzymes are more stable due to increased number of bonds in tertiary structures (hydrogen and sulphur bridges)
-The shape of these enzymes are more resistant to change as temperature rises.

Question 25

What does a change in pH refer to?

Answer 25

A change in hydrogen ion concentration.

Question 26

What hold proteins in their precise shapes?

Answer 26

Hydrogen bonds and ionic bonds between amino acid R-groups.

Question 27

What are these bonds a result of?

Answer 27

A change in interactions between polar and charged R-groups.

Question 28

What is the hydrogen ion concentration in a low pH?

Answer 28

More hydrogen ions. (Acid)

Question 29

What is the hydrogen ion concentration in a high pH?

Answer 29

Less hydrogen ions. (Alkaline)

Question 30

What is the optimum pH?

Answer 30

Active site will only be in the right shape at a certain ion concentration.

Question 31

What happens when there is a change from the optimum pH?

Answer 31

Active site is altered. If the pH then returns to optimum then the protein with resume its normal shape again and catalyse the reaction.

Question 32

What is this process called?

Answer 32

Renaturation.

Question 33

What happens when pH changed significantly?

Answer 33

Structure of the enzyme is irreversibly altered and active site will no longer be complementary.

Question 34

What has now happened to this enzyme?

Answer 34

-Denatured -Substrates can no longer bind to active site -Reduces ROR

Question 35

What happens in a Low pH?

Answer 35

R groups can't interact as much with each other which leads to bonds breaking and enzyme shape changing.

Question 36

What happens in a High pH?

Answer 36

Reverse of low. Shape of enzyme will change as pH changes so will only function with a narrow pH range.

Question 37

What happens when the concentration of substrate is increased?

Answer 37

The number of substrate molecules, atoms or ions in a particular area or volume increases.

Question 38

What does this increase lead to?

Answer 38

A higher collision rate with the active sites of enzymes and the formation of more enzyme-substrate complexes.

Question 39

What happens to the number of active sites when the concentration of enzymes increase?

Answer 39

AS number increases in a particular area/volume which leads to the formation of enzyme-substrate complexes at a faster rate.

Question 40

What is it called when the rate of reaction is increased up to its maximum?

Answer 40

Vmax

Question 41

What happens the the Rate of Reaction increases up to its maximum ? (Vmax)

Answer 41

All the active sites are occupied by substrate particles and no more enzyme-substrate complexes can be formed until products are released from active site.

Question 42

How can this Rate of Reaction be increased?

Answer 42

By adding more enzyme or increasing the temperature.

Question 43

What happens if the concentration of the enzyme is increased?

Answer 43

More active sites are available so reaction rate can increase to a higher Vmax.

Question 44

In this scenario, what is the limiting factor? And what will increasing this allow?

Answer 44

Concentration of substrate and increasing this will allow reaction rate to rise until new Vmax is reached.