3.1.4.1 GENERAL PROPERTIES OF PROTEINS

Question 1

What are proteins made out of?

Answer 1

Amino acids held together by peptide bonds

Question 2

What determines a proteins function?

Answer 2

• sequence
• type and number of amino acids

Question 3

What are amino acids and how many of them are there?

Answer 3

• monomers of proteins
• 20 amino acids found in proteins common to all living organisms

Question 4

What is the general structure of an amino acid?

Answer 4

A central carbon atom bonded to:
- an amine group -NH2
- a carboxylic acid group- COOH
- a hydrogen atom
- an R group

Question 5

What is an R group on an amino acid?

Answer 5

The only difference between amino acids and

Question 6

How is a peptide bond formed?

Answer 6

1. A hydroxyl (-OH) is lost form the carboxylic group of one amino acid and a hydrogen atom is lost from the amine group of another amino acid
2. The remaining carbon atom from the first amino acid bonds to the nitrogen atom of the second amino acid

Question 7

What kind of reaction is the formation of a peptide bond?

Answer 7

Condensation reaction

Question 8

What are dipeptides?

Answer 8

Formed by the condensation of two amino acids

Question 9

What are polypeptides?

Answer 9

Formed by the condensation of many (3 or more) amino acids

Question 10

What are the four levels of protein structure?

Answer 10

1. Primary
2. Secondary
3. Tertiary
4. Quaternary

Question 11

Describe the structure of a primary level of protein structure:

Answer 11

Order of amino acids in a polypeptide chain

Question 12

Describe the structure of secondary level protein structure:

Answer 12

B- sheet
Folding alpha helixes

Question 13

Describe the structure of a tertiary level protein:

Answer 13

B-sheets fold up to become 3D
Can be globular of fibrilous

Question 14

Describe the structure of a quaternary level protein:

Answer 14

Association of two or more polypeptide charges and non- protein groups, to form a 3D structure

Question 15

What type of bonds are in a primary level protein?

Answer 15

Peptide bonds

Question 16

What type of bonds are in a secondary level protein?

Answer 16

Hydrogen bonds

Question 17

What type of bonds are in a tertiary and quaternary level protein?

Answer 17

Ionic forces, disulphide bridges, hydrogen bonds, London forces

Question 18

Where do the bonds form in a primary level protein?

Answer 18

Between amine and carboxylic groups of amino acids

Question 19

Where do bonds form in a secondary level protein?

Answer 19

Resides of amine and carboxylic groups in the chain of amino acids

Question 20

Where do bonds form in a tertiary and quaternary level protein?

Answer 20

Between R groups- type of bond/ IM force depends in properties of R group

Question 21

Example of a globular protein?

Answer 21

Haemoglobin

Question 22

Example of a fibrous protein?

Answer 22

Collagen

Question 23

Why is it possible to form millions of different proteins?

Answer 23

20 amino acids- can form in loads of different orders

Question 24

Are globular proteins soluble in water?

Answer 24

Yes

Question 25

Are globular proteins soluble in water?

Answer 25

Yes

Question 26

Why are globular proteins being soluble good?

Answer 26

They can be easily transported around around organisms involved in metabolic reactions

Question 27

Do globular proteins have specific shapes?

Answer 27

Yes due to the folding of the protein due to the interactions between the R groups and therefore have specific shapes

Question 28

Do globular proteins have specific shapes?

Answer 28

Yes due to the folding of the protein due to the interactions between the R groups and therefore have specific shapes

Question 29

Why are the specific shapes of globular proteins good?

Answer 29

Enzymes can catalyse specific reactions and immunoglobulins can respond to specific antigens

Question 30

What is a conjugated protein?

Answer 30

Contains a prosthetic group- haemoglobin contains haem

Question 31

What are fibrous proteins?

Answer 31

Long strands of polypeptide chains that have cross-linkages due to hydrogen bonds

Question 32

Do fibrous proteins have a structure?

Answer 32

They have little or no tertiary structure

Question 33

Are fibrous proteins soluble or insoluble in water?

Answer 33

Insoluble due to the large number of hydrophobic R groups

Question 34

Shape of fibrous proteins:

Answer 34

Long strands

Question 35

Function of fibrous proteins:

Answer 35

Structural

Question 36

Examples of fibrous proteins:

Answer 36

Collagen, keratin, myosin

Question 37

Function of globular proteins:

Answer 37

Functional/ physiological

Question 38

Example of globular proteins:

Answer 38

Haemoglobin, enzymes