proteins

Question 1

What percentage of the human body is protein?

Answer 1

18%

Question 2

Name some examples of the functions of proteins.

Answer 2

Enzymes, structural proteins, signalling proteins, storage proteins, antibodies in the blood, transport proteins.

Question 3

What features do all amino acid’s have?

Answer 3

They all have an Amine group at one end, and a carboxyl group at the other.

Question 4

What is the variable part of an amino acid?

Answer 4

The R group

Question 5

How many types of amino acid occur in life?

Answer 5

20 occur in life – this refers to the amount of R groups

Question 6

What is the simplest R group?

Answer 6

Glycine which is simply one hydrogen

Question 7

What amino acid R group does every protein start with?

Answer 7

Methionine, shown by the simple capital M

Question 8

What properties can R groups have?

Answer 8

They can be: nonpolar, hydrophobic, polar, hydrophilic, ionic etc

Question 9

What is the name for two amino acids joined together?

Answer 9

To amino acid is joined together by peptide bond are called a dipeptide.

Question 10

What is a protein?

Answer 10

A molecule consisting of one or more polypeptide chain.

Question 11

Where is a peptide bond formed?

Answer 11

A peptide bond is formed between the Amine group of one amino acid and the carboxyl end of the other.

Question 12

What is a simple protein?

Answer 12

A simple protein is a protein containing amino acids only.

Question 13

What is a conjugated protein?

Answer 13

Containing a non-amino acid part which is called a prosthetic group.

Question 14

What is meant by the term primary structure?

Answer 14

The order of amino acid’s within a protein

Question 15

What is meant by secondary structure? And what are the two types?

Answer 15

Secondary structure is when the polypeptide chain begins to fold it can do this in two ways: the first is an alpha helix, the second is called a beta pleated sheet.

Question 16

What bonds are involved in the secondary structure?

Answer 16

Hydrogen bonds form between nonadjacent amino acids - this holds the secondary structure in place.

Question 17

What is meant by the tertiary structure?

Answer 17

The overall three-dimensional shape of a polypeptide chain after it has coiled in multiple ways.

Question 18

Name the types of bonds that hold the tertiary structure in place.

Answer 18

Bond between R groups include: Ionic bonds, hydrogen bonds, disulphide bonds, and hydrophobic interactions.

Question 19

Describe the term fibrous protein.

Answer 19

Fibrous proteins consist of parallel polypeptide chain is cross-linked at intervals to form long fibres or sheets. Fibrous proteins are usually in soluble in water and physically tough which suits them for them mainly structural functions.

Question 20

Describe what is meant by the term globular protein.

Answer 20

Are globular protein is when the polypeptide chain is tightly folded to form a spherical shape. Many globular proteins are folded so that the hydrophobic groups on the inside of the molecule and the hydrophilic groups face outwards, making these proteins soluble in water.

Question 21

What is meant by the term quaternary structure?

Answer 21

When a protein is made up of more than one polypeptide chain.

Question 22

Give some information about the structure and function of insulin.

Answer 22

It is a globular protein.
It is a hormone that regulates blood glucose concentration.
It is soluble as it is transported in blood and as a precise shape to fit specific receptors.
It only has a tertiary structure.

Question 23

Give some information about the structure and function of haemoglobin.

Answer 23

It has a good quaternary structure made of four polypeptides.
This consists of two alpha and to beta subunits.
Each sub unit contains a prosthetic haem group. This is able to combine reversibly with oxygen.
It is soluble and globular as in blood it is used for transport.

Question 24

Give some information about the structure and function of catalase.

Answer 24

Catalase is an enzyme, which increases reaction rates in specific reactions.
It has a Quaternary structure and also contains four haem groups.
Iron 2 ions in these haem groups allow it to interact with hydrogen peroxide and speed up its decomposition.

Question 25

Give some information on the structure and function of keratin

Answer 25

It is a fibrous protein present in skin hair and nails
It contains a lot of disulphide bonds making it very strong and inflexible.
The more sulphur it contains the less flexible it will be.

Question 26

Give some information on the structure and function of elastin.

Answer 26

Elastin is a fibrous protein found in elastic fibres such as the walls of blood vessels or the alveoli.
It has a structure that allows it to expand and return to normal shape again.
It is a quaternary protein made from many stretchy molecules called tropoelastin.
Many soluble tropoelastin link to form a large insoluble molecule.
each one contains alternate hydrophobic and lysine rich areas - these form hydrophobic interactions and covalent bonds

Question 27

Give some information on the structure and function of collagen.

Answer 27

Courage is a fibrous protein found in connective-tissue such as skin tendons and ligaments.
Different forms of collagen exist but all are made up of three polypeptide wound together in a ropelike structure.
Collagen has flexibility.
Polypeptide chains form the triple helix, every third amino acid is glycine which is small so allows it to pack closely together.