Enzymes

Question 1

What are enzymes

Answer 1

They are biological catalysts that speed up chemical reactions without being changed

Question 2

What is a catalyst

Answer 2

A chemical that increases the rate of reaction but remains unchanged at the end of the reaction

Question 3

What is an active site

Answer 3

The area of an enzyme where a substrate will bind

Question 4

What is a substrate

Answer 4

A molecule upon which an enzyme will act

Question 5

What is lock and key model

Answer 5

The model used to describe the binding of specific substances to specify enzymes

Question 6

What is monosaccharide

Answer 6

A single sugar molecule

Question 7

What is disaccharide

Answer 7

2 single sugar molecule bonded together

Question 8

What is polysaccharide

Answer 8

Multiple sugar molecules bonded together

Question 9

What is a anabolic reaction

Answer 9

Building larger molecules from smaller molecular

Question 10

What is a catabolic reaction

Answer 10

Breaking down larger molecules into smaller molecules

Question 11

How will a higher temperature increase the rate of reaction and cause denaturation

Answer 11

The enzymes will gain kinetic energy and so there will be more frequent collision between the enzyme and substrate which will increase the rate of reaction. This will happen until the optimal temperature. After that point the bonds holding the enzyme will start to break. This will cause the active site to lose its shape, thus the enzyme becomes denatured and doesn’t bind with the substrate anymore.

Question 12

Describe how an enzyme can break down a substrate

Answer 12

The reaction would be called a catabolic reaction. The enzyme will bind with the enzyme at the active site. It will break the bonds of the substrate turning it into smaller soluble bits.

Question 13

What is activation energy

Answer 13

Its the amount of energy needed to start a chemical reaction.

Question 14

What is the aim of the practical of enzymes and temperature

Answer 14

To investigate how enzymes activity can be affected by changes in temperature

Question 15

Equipment list

Answer 15

Pieces of fresh and boiled liver Scalpel
Weighing scales
Hydrogen peroxide
Distilled water Test tubes Ruler
Stop watch

Question 16

Risk assessment

Answer 16

Goggles - Hydrogen peroxide is an irritant and corrosive. It could damage the eyes.

Question 17

Method

Answer 17

1. Take one piece of fresh liver and one piece of boiled liver.
2. Cut them to make sure they are the same size/mass (this may have been done for you).
3. Place each piece in a separate test tube.
4. Add the 5ml of hydrogen peroxide to each test tube and start the stopwatch.
5. After 5 minutes record the height of the froth produced.
6. Repeat the experiment.

Question 18

What happens in this practical

Answer 18

Catalase is an enzyme found in living tissue. Its role is to break down the toxic waste product Hydrogen peroxide into oxygen and water.(froth)

Question 19

Conclusion

Answer 19

As the temperature increases he enzyme activity increases until an optimal temperature. This is shown in the results as the fresh liver has a mean foam height of 15.73cm and the boiled liver has a mean foam height of 8.87cm

Question 20

How does an enzyme become denatured

Answer 20

The binds holding the enzyme together break causing the active site to change shape, therefore the substrate will no longer fit into the active site causing the enzyme to become denatured

Question 21

What is the aim of the practical of enzymes and pH

Answer 21

Investigate how enzyme activity can be affectedby changes in pH

Question 22

Equipment list

Answer 22

•test tubes
•a test tube rack of buffered solutions covering a range of pH
•water bath
•spotting tiles
•5cm3 measuring cylinder
•pipettes
•a stop clock
•starch solution
•amylase solution
•iodine solution

Question 23

Method

Answer 23

1.Place one drop of iodine solution into each depression on the spotting tile.
2.In a clean test tube, add 2 ml of starch to 2ml of buffered pH solution.
3.Add 2ml amylase to the starch and buffered pH solution and begin timing immediately.
4.Every 30 seconds remove a drop of the mixture and put this into one of the iodine depressions. Watch for a colour change.
5.Continue until the mixture remains orange when added to the buffer solution.
6.Record your results

Question 24

Method

Answer 24

1.Place one drop of iodine solution into each depression on the spotting tile.
2.In a clean test tube, add 2 ml of starch to 2ml of buffered pH solution.
3.Add 2ml amylase to the starch and buffered pH solution and begin timing immediately.
4.Every 30 seconds remove a drop of the mixture and put this into one of the iodine depressions. Watch for a colour change.
5.Continue until the mixture remains orange when added to the buffer solution.
6.Record your results