Enzymes

Question 1

What is an enzyme

Answer 1

An enzyme is a protein which acts as a biological catalyst

Question 2

What are enzymes made up of

Answer 2

Enzymes are made up of protein molecules (made up of amino acids folded to produce a specific shape

Question 3

How many times can an enzyme be used

Answer 3

An enzyme is reusable

Question 4

What are the factors that affect enzymes

Answer 4

Enzymes are affected by temperature and pH.

Question 5

What does it mean if it said an enzyme is specific

Answer 5

Each enzyme catalyses one particular reaction

Question 6

What is a catalyst

Answer 6

A catalyst is a substance which speeds up the rate of reaction but it is not used up or changed itself.

Question 7

What do enzymes do during digestion

Answer 7

During digestion, enzymes break down large, insoluble food molecules into smaller, soluble ones which can be absorbed through the small intestine wall to enter the bloodstream

Question 8

State the two types of enzymes

Answer 8

Anabolic enzymes (build up)
Catabolic enzyme (breaks down)

Question 9

Why do enzymes only catalyse one specific reaciton

Answer 9

Enzymes only catalyse one specific reaction.

This is because, an enzyme’s active site has a specific shape.

Foran enzyme to work (for the reaction to occur), the shape of the enzyme’s active site has to be complimentary to the shape of one particular substrate, so that the substrate can bind to (fit into) the enzymes active site) and an reaction can occur

If the substrate doesn’t match the enzyme’s active site (if they are not complimetnary), then the reaction won’t be catalysed

______
For an enzyme to work(for the reaction to occur), the substrate has to fit into (bind to) its active site.

Question 10

Describe the lock and key theory

Answer 10

1) The shape of the enzyme’s active site is complimentary to the shape of one particular substrate.
2) The two bind together to form an enzyme substrate complex.
3) The reaction between them takes place rapidly (to produce smaller molecules)
4) The products are released from the enzyme’s active site.
The enzyme molecule is unchanged and can be reused.

Question 11

Where is amylase produced

Answer 11

Salivary glands, pancreas and small intestine

Question 12

Where is protease produced

Answer 12

Stomach, pancreas and small intestine

Question 13

Where is lipase produced

Answer 13

Pancreas and small intestine

Question 14

What is starch broken down into by the amylase enzyme

Answer 14

Sugars e.g. glucose

Question 15

What is protein broken down into by the protease enzyme

Answer 15

amino acids

Question 16

What are lipids broken down into by the lipase enzyme

Answer 16

fatty acid and glycerol.

Question 17

Where can enzymes be found?

Answer 17

Enzymes can be found in animals, plants and micro-organisms

Question 18

Describe and explain the trend in a temperature/rate of reaction enzyme graph

Answer 18

As the temperature increases, the rate of reaction increases. This is because as the temperature increases, the enzyme and the substrate are moving faster (have more kinetic energy), so there are more collisions per second (more frequent collisions) between the substrate and the active site.

At a certain temperature, the enzyme is working as fast as possible. This is called the optimum temperature.
At this point, there is the maximum frequency of successful collisions between the substrate and the active site

As the temperature increases beyond the optimum, the rate of reaction rapidly decreases to zero (the enzyme has denatured and has stops working)

This is because at high temperatures, the long amino acid chains begin to unravel and as a result the shape of the active site changes. Now the substrate no longer fits perfectly into the active site. The active site is denatured.
The enzyme can no longer catalyse the reaction

The too low/too high or too high temperature would break the bonds in the enzyme and change the shape of the enzyme’s active site.
The enzyme would denature
This would mean the substrate would no longer fits perfectly into the active site.

The enzyme can no longer catalyse the reaction (the enzyme wouldn’t work anymore)

Question 19

What is the optimum temperature of most human enzymes

Answer 19

37 degrees celcius which is human body temperature

Question 20

How does pH effect enzymes

Answer 20

The enzyme has an optimum pH where rate of reaction is maximum.
If the pH is made more acidic or more alkaline then the rate of reaction drops to zero.

This is because, a change in pH affects the shape of the active site of an enzyme.
The Shape of the active site of an enzyme comes from forces between the different parts of the protein molecule. These forces hold the folded chains in place. A change in pH can affect these forces, changing the shape of the molecule. As a result, the specific shape of the active site is lost, so the enzyme no longer acts as a catalyst, and becomes denatured.

Question 21

Describe how temperature affects the enzyme function
Use the graph

Answer 21

Initially, as the temperature increases, the rate of enzyme activity also increases, up to 40 degrees celcius, which is optimum temperature. After 40 degrees celcius, as the temperature increases the rate of enzyme activity decreases

Question 22

Describe how high temp and very low/high pH affect enzymes

________________________________

Explain what effect a very low pH or high pH or a very high temperature would have on the activity of the enzyme

Answer 22

The too low/too high or too high temperature would break the bonds in the enzyme and change the shape of the enzyme’s active site.

The enzyme would denature
This would mean the substrate would no longer fits perfectly into the active site.

The enzyme can no longer catalyse the reaction (the enzyme wouldn’t work anymore)

Question 23

What do enzymes control

Answer 23

Enzymes control metabolism (the sum of all the reactions in a cell or in the body)

Question 24

Define active site

Answer 24

The site on an enzyme where the substrate (reactants) bind