Proteins

Question 1

What are proteins made from?

Answer 1

Proteins are made from long chains of smaller molecules called amino acids. These long chains are folded into particular shapes.

Question 2

What happens if the shape of an enzyme changes?

Answer 2

If the shape of an enzyme changes, it may no longer work (it is said to have been ‘denatured’)

Question 3

What are enzymes?

Answer 3

Enzymes are biological catalysts. There are optimum temperatures and pH values at which their activity is greatest. Enzymes are also proteins.

Question 4

What are proteins?

Answer 4

Proteins are polymers. They are built up in cells in monomers called amino acids join together end to end.

Question 5

What is glycine?

Answer 5

Glycine is an amino acid

Question 6

What is alanine?

Answer 6

Alanine is an amino acid.

Question 7

How many naturally occurring amino acids are there?

Answer 7

There are only about 20 different amino acids. However, each protein molecule has hundreds, or even thousands, of them joined together in a unique sentence (this gives each protein its own individual properties)

Question 8

What is particularly important for antibodies and enzymes?

Answer 8

The particular shape that a protein molecule has allows other molecules to fit into it.

Question 9

What is the name of the place where substrate molecules fit?

Answer 9

The active site

Question 10

How can enzymes be denatured?

Answer 10

Enzymes can be denatured by high temperatures or extremes of pH.

Question 11

Why is it wrong to say that enzymes have been killed?

Answer 11

It’s is wrong to say that an enzyme has been killed. Although enzymes are made by living things, they are proteins and not alive. You must say ‘denatured’.

Question 12

What happens to enzymes as the temperature increases?

Answer 12

As the temperature increases, so does the rate of reaction. But very high temperatures denature enzymes.

Question 13

How can changes in pH affect enzymes?

Answer 13

Changes in pH alter an enzyme’s shape. Different enzymes work best at different pH values. The optimum pH for an enzyme depends on where it normally works.

Question 14

Which enzymes work best inside cells?

Answer 14

The enzymes involved in respiration, photosynthesis and protein synthesis work inside cells. Other enzymes are produced by specialized cells and released from them.

Question 15

Where is amylase produced?

Answer 15

Salivary glands, pancreas and small intestine

Question 16

Where is protease produced?

Answer 16

Stomach, pancreas and small intestine

Question 17

Where is lipase produced?

Answer 17

Pancreas and small intestine

Question 18

What is the function of amylase?

Answer 18

Amylase catalyses the breakdown of starch into sugars in the mouth and small intestine.

Question 19

What is the function of protease?

Answer 19

Proteases catalyse the breakdown of proteins into amino acids in the stomach and small intestine

Question 20

What is the function of lipase?

Answer 20

Lipase catalyse the breakdown of fats and oils into fatty acids and glycerol in the small intestine.

Question 21

What acid does the stomach produce?

Answer 21

It produces hydrochloric acid.

Question 22

How is the stomach producing hydrochloric acid useful?

Answer 22

It helps begin digestion, and it kills many harmful microorganisms that might have been swallowed along with the food.

Question 23

When do the enzymes in the stomach work best?

Answer 23

The enzymes in the stomach work best in acidic conditions - in other words, at a low pH.

Question 24

When do the enzymes in the small intestine work best?

Answer 24

The enzymes in the small intestine work best in alkaline conditions, but the food is acidic after being in the stomach.

Question 25

What does bile do?

Answer 25

A substance called bile neutralises the acid to provide the alkaline conditions needed in the small intestine.

Question 26

Where is bile produced and stored?

Answer 26

Bile is produced in the liver and stored in the gall bladder.

Question 27

What are the three most common enzymes?

Answer 27

Lipase - breaks down fats
Protease - breaks down proteins
Carbohydrase - breaks down carbohydrates

Question 28

What is protease used for?

Answer 28

To pre-digest proteins during the manufacture of baby foods.

Question 29

What is lipase used for?

Answer 29

Used together with protease in biological detergents to break down (digest) the substances in stains into smaller, water soluble substances

Question 30

What is carbohydrase used for?

Answer 30

To convert starch syrup, which is relatively cheap, into sugar syrup, which is more valuable - for example, as an ingredient in sports drinks.

Question 31

What is isomerase used for?

Answer 31

To convert glucose syrup into fructose syrup - fructose is sweeter than glucose, so it can be used in smaller amounts in slimming foods.

Question 32

Are enzymes cheap or expensive to make?

Answer 32

Many enzymes are expensive to produce. Enzymes allow reactions that normally need expensive, energy-demanding equipment to happen at normal temperatures and pressures.