Enzymes & rate of reaction

Question 1

What are enzymes?

Answer 1

Enzymes are tertiary proteins, meaning they are a specific shape. They’re biological catalysts, as they’re found in nature and accelerate chemical reactions.

Question 2

What is collision theory?

Answer 2

This is how reactions work. It states that all molecules must collide with sufficient force to kick start a reaction.

Question 3

What is meant by activation energy?

Answer 3

The minimum energy required to cause a reaction/process to occur.

Question 4

How do enzymes affect activation energy?

Answer 4

Having enzymes present, reduces the minimum activation energy needed for a reaction.

Question 5

What is the lock and key model?

Answer 5

This is where the substrate fits perfectly into the active site of an enzyme.

|_____ []Substrate

Question 6

What is the induced fit model?

Answer 6

This is where the active site will mold around the substrate so it can bind to it.

Question 7

What the binding process of enzymes?

Answer 7

• The enzyme collides with the substrate molecule.
• The substrate binds to the active site.
• An enzyme substrate complex is now formed.
• The substrate is broken down.
• The products are released from the active site.
• The enzyme is free to collide with the next substrate molecule.

Question 8

What is the amylase practical?

Answer 8

This is when a solution is tested for starch and glucose, through the addition of iodine. If starch is present the solution will turn dark and if glucose is present the solution will stay orange.

Question 9

Explain the process of the amylase practical?

Answer 9

• Take 2 test tubes, one with amylase solution and one with starch solution.
• Place both test tubes in a water bowl and leave them until they reach the same temperature. This should be measured with a thermometer.
• Then pour the solutions into each other and leave them in the water bath for 1 minuet.
• Put 3 drops of iodine in each dimple of a dimple tray.
• Every minuet, put some of the mixture in a dimple.
• Repeat this with multiple different temperatures.

Question 10

What is a controlled variable?

Answer 10

This is something that remains constant and is unchanged throughout.

Question 10

What is an independent variable?

Answer 10

This is something that is intentionally changed or manipulated.

Question 11

What is a dependant variable?

Answer 11

This is something that is measured and is affected by the independent variable.

Question 12

What is meant by the rate of reaction?

Answer 12

This is the speed at which a reaction takes place.

Question 13

How do you work out the rate of a reaction?

Answer 13

You measure how the concentration of a product increases over time or how the substrate concentration decreases over time.

Substrate —————> Product
(Enzyme)

Question 14

What phrases could you use to describe the rate of a reaction?

Answer 14

• Starts quick.
• Slows down.
• Plateaus off.
• Stops.

Question 15

What does a steep line in a graph say about the rate of reaction?

Answer 15

This indicates the reaction is faster.

Question 16

How can you increase the rate of reaction?

Answer 16

• You could increase the substrate and enzyme concentration so more complexes are formed.
• You could increase the temperature as this would increase the kinetic energy of the molecules, increasing the amount of collisions as the particles are moving faster. However, if the temperature is too high the enzymes will denature.
• You could increase the PH.

Question 17

How would you calculate the rate of reaction using a graph?

Answer 17

• Find the point at which the line stops being straight, and draw a line downwards.
• This downwards line should stop at the same point at which the line started. Then draw a line from this point, towards the y axis, forming a triangle.
• Then work out the value of △x and △y.
• △x = The point at which the triangle meets the y axis.
• △y = The point at which the triangle stops being straight according to the y axis, take away the point at which the line stops being straight according to the x axis.
• Then to work out the rate of reaction per second do △y / △x.