Proteins

Question 1

Polypeptides

Answer 1

Amino acids are the monomers that join together to form polymers called polypeptides (proteins).

Question 2

Structure of proteins

Answer 2

Proteins are made up of amino acids.
Dipeptides are formed from the condensation of two amino acids.
Polypeptides are formed by the condensation of many amino acids

Question 3

R group

Answer 3

The R group is different in each amino acid.
The R group determines how the amino acid interacts and bonds with other amino acids in the polypeptide.

Question 4

How many different amino acids

Answer 4

20

Question 5

Fours groups surrounding the central carbon atom in an amino acid

Answer 5

Amine group
Carbóxyl group
Hydrogen atom
R group

Question 6

Function of protein (antibodies)

Answer 6

Antibodies are made up of polypeptide chains.
Antibodies are used in the immune response.
Antibodies are diverse proteins.
Each antibody has a different sequence of amino acids.

Question 7

Transport proteins

Answer 7

Transport proteins include channel proteins.
transport molecules across the cell membrane.
transport molecules that are too large to diffuse freely or molecules that carry a charge.

Question 8

Structural proteins

Answer 8

are long, strong polypeptide chains.
connected by cross-links that hold the chains parallel to each other.
E.g. Collagen and keratin.

Question 9

Monomer

Answer 9

One amino acid

Question 10

Dipeptide

Answer 10

Two amino acids

Question 11

Polypeptide

Answer 11

More than two amino acids

Question 12

Glycine

Answer 12

Exception contains no carbon only one hydrogen atom

Question 13

Amino acids

Answer 13

Linked together by condensation reactions to form dipeptides and polypeptides. A molecule of water is released during the reaction. Bonds formed between amino acids are called peptide bonds .
Reverse reaction happens hydrolysis when dipeptides and polypeptides are broken down

Question 14

Primary structure

Answer 14

This is the sequence of amino acids in the polypeptide chain

Question 15

Secondary structure

Answer 15

Polypeptide chain doesn’t remain flat and straight. Hydrogen bonds form between the amino acids in the chain. This makes it automatically coil into a alpha or beta pleated sheet

Question 16

Tertiary structure

Answer 16

Coiled or folded chain is often folded or pleated more. More bonds form between different parts of the polypeptide chain including hydrogen and ionic bonds.
Disulfide bridges form whenever two molecules of the amino acid cysteine come close together - the sulphur atom in one cysteine bonds to the sulphur atom in the other

Question 17

Quaternary structure

Answer 17

The way these polypeptide chains are assembled together

Question 18

Biuret test for proteins

Answer 18

1. Test solution needs to be alkaline so first add a few drops of sodium hydroxide solution
2. Then add some copper sulfate solution
   If protein is present the solution turns purple if there is none it stays blue