Factors Affecting Enzymes 4.2

Question 1

Temperature

Answer 1

As the temperature increases, the substrates and enzymes have more kinetic energy so more successful collisions occur and the rate of the reaction increase.

Question 2

Q10

Answer 2

This is the temperature coefficient which is a measure of the change in rate by every rise in 10 degrees. It usually doubles.

Question 3

Optimum Temperature

Answer 3

This is the temperature where the rate of the enzyme is the highest or at its Vmax. This means the most ES complexes are being made.

Question 4

What happens when the temperature gets too high?

Answer 4

The enzyme will denature. This occurs because when the temperature gets high, the enzyme vibrates which puts a strain on the bonds within the tertiary structure of the enzyme and they break so the shape of the enzyme and its active site change. This means it’s unable to bind the substrate as it doesn’t have a complementary shape.

Question 5

What happens in an extreme hot environment?

Answer 5

The enzymes are adapted to have more bonds joining their tertiary structure together so that it is more stable and won’t be broken as easily.

Question 6

What happens in an extreme cold environment?

Answer 6

The enzymes are adapted so their active site is more flexible and can bind to more substrates successfully. They are less stable, so can be broken easier.

Question 7

Describe the graph of temperature against rate

Answer 7

When the temperature is low, the enzymes and substrates don’t have a lot of kinetic energy so the rate is low, but as the temperature increases, so does the rate. When it reaches the optimum temperature, the rate of reaction is at it’s highest, but as the temp keeps rising, the enzyme denatures so the rate falls quickly as the enzyme can’t bind to the substrates.

Question 8

pH

Answer 8

This is the concentration of hydrogen ions when there are a lot of hydrogen ions, it’s acidic and when there aren’t a lot of hydrogen ions, its alkali

Question 9

Optimum pH

Answer 9

This is when there’s a certain concentration of hydrogen ions in the solution that is ideal for the enzyme to be at it’s fastest rate. If the pH strays a little bit, the enzyme will denature, but as soon as the pH goes back to optimum, it will renature.

Question 10

Describe the graph of pH against rate

Answer 10

At its optimum temperature, there is a high rate reaction, however as the pH gets further from the optimum temperature, the rate of reaction decreases more and more. It will eventually get to zero.

Question 11

What happens if the pH gets too high?

Answer 11

There will be too many hydrogen ions so they will interact with the charged and polar R groups which means they can’t interact with each other so the tertiary structure of the enzyme will be permanently changed, therefore it will be denatured and unable to bind to the substrate.

Question 12

What happens if the pH gets too low?

Answer 12

There won’t be enough hydrogen ions so the shape of the enzyme will change and it will be denatured, only able to bind to the substrate at a narrow pH.

Question 13

Substrate concentration

Answer 13

The more substrates there are, the faster the rate of the reaction as there is a greater rate of successful collisions.

Question 14

Describe the graph of substrate concentration

Answer 14

As the substrate concentration increases, the rate of the reaction increases, but the graph levels off when it reaches the Vmax which is when all of the enzymes are bound to a substrate.

Question 15

Enzyme concentration

Answer 15

As the enzyme concentration increases, so does the rate of the reaction.

Question 16

Describe the graph of enzyme concentration

Answer 16

As the enzymes increase so does the rate of the reaction, but then all of the substrates are the limiting factor as they are used up so it falls dramatically, vertically.

Question 17

How do you calculate rate?

Answer 17

substrate conc/ time or 1/time

Question 18

How do you investigate factors affecting the rate of enzyme activity?

Answer 18

You can use catalase and hydrogen peroxide in a conical flask. Inject the catalase and have a tube to let the products flow into the water. Oxygen is produced as a product so will form bubbles, count the number of bubbles in a certain time to get the rate. You can alter the temperature, pH etc…

Question 19

Serial dilutions

Answer 19

This is to see the effect of different substrate or enzyme concentrations. Start with 100% stock and take 1ml of it and put it in 9ml of water. Then take 1ml of this product and put it into 9ml of water. Do this 4 more times until you get lots of concentrations.