Protein

Question 1

What elements do proteins contain?

Answer 1

Proteins contain elements C, H, O, and Nitrogen. Some also contain phosphorus (P), sulphur (S), and iron (Fe).

Question 2

Are proteins soluble in water?

Answer 2

Proteins are not soluble in water; they form a colloidal system where particles are suspended evenly (e.g. milk).

Question 3

What is the monomer of proteins?

Answer 3

The monomer of proteins is an amino acid.

Question 4

How are amino acids joined together?

Answer 4

Amino acids are joined by a peptide bond.

Question 5

What is a dipeptide?

Answer 5

A dipeptide is a polymer formed when 2 amino acids are joined.

Question 6

What is a polypeptide?

Answer 6

A polypeptide is a polymer formed when more than 2 but less than 50 amino acids are joined.

Question 7

What is a protein?

Answer 7

A protein is a polymer formed when more than 50 amino acids are joined.

Question 8

How are peptide bonds formed?

Answer 8

Peptide bonds form through dehydration synthesis/dehydrolysis.

Question 9

What is the structure of proteins?

Answer 9

Proteins are made of chains of amino acids that fold into complex 3D structures held in place by disulphide bonds and weak hydrogen bonds.

Question 10

What happens to proteins when they are denatured?

Answer 10

Proteins are sensitive to heat and incorrect pH, which can break the bonds holding their 3D structure, causing them to unfold and change shape.

Question 11

What is the consequence of denaturing a protein?

Answer 11

The protein will no longer be able to carry out its role, and this process is irreversible.

Example: Cooking raw egg white.

Question 12

What are the functions of proteins?

Answer 12

Proteins are important for growth and repair in cells, form the structure of organisms, carry oxygen in red blood cells (haemoglobin), serve as enzymes, provide immunity (antibodies), and act as a source of energy.

Question 13

What are enzymes?

Answer 13

Enzymes are large globular proteins that control metabolic reactions and act as biological catalysts.

Question 14

What is a catalyst?

Answer 14

A catalyst speeds up the rate of a reaction without being changed.

Question 15

How do enzymes affect reaction energy?

Answer 15

Enzymes lower the amount of energy needed for a reaction.

Question 16

How quickly can enzymes work?

Answer 16

Enzymes can catalyse thousands of reactions per second.

Question 17

What are intracellular and extracellular enzymes?

Answer 17

Intracellular enzymes work within cells, while extracellular enzymes are secreted and work outside of cells.

Question 18

What is the lock and key model?

Answer 18

The lock and key model explains enzyme specificity, where the enzyme is the lock and the substrate is the key, fitting perfectly at the active site.

Question 19

What happens when an enzyme and substrate bind?

Answer 19

When they bind, an activated enzyme-substrate complex is formed, and the chemical reaction takes place.

Question 20

What happens to enzymes after a reaction?

Answer 20

After the reaction, the enzyme is unchanged and can catalyse another reaction.

Question 21

Can enzymes be denatured?

Answer 21

Yes, enzymes can be denatured by high temperatures and incorrect pH, which changes their shape and active site, rendering them inactive.

Question 22

What is the optimal temperature for enzymes in the human body?

Answer 22

The optimal temperature for enzymes in the human body is 37°C.

Question 23

What happens to enzymes below their optimal temperature?

Answer 23

Below the optimal temperature, enzymes are inactive but not permanently affected.

Question 24

What happens to enzymes above their optimal temperature?

Answer 24

Above the optimal temperature, enzymes will denature, decreasing their activity permanently.

Question 25

What pH do most enzymes work at?

Answer 25

Most enzymes work at pH-neutral, but extreme pH changes can cause denaturation.

Question 26

How do substrate and enzyme concentrations affect reaction rates?

Answer 26

Higher concentrations of substrates and enzymes speed up the reaction rate.

Question 27

What are some uses of enzymes in biological washing powders?

Answer 27

Biological washing powders contain enzymes like lipase and protease that break down stains and work at low temperatures under 40 degrees.

Question 28

What is the function of protease in meat tenderisers?

Answer 28

Protease in meat tenderisers breaks down protein.

Question 29

What enzymes are used to soften and brighten cotton fabrics?

Answer 29

Cellulases are used to soften and brighten the colours of cotton fabrics.

Question 30

How is lactose-free milk produced?

Answer 30

Lactose-free milk is produced by adding lactase to pre-digest lactose for lactose-intolerant individuals.