Proteins (2.9)

Question 1

Describe how amino acids react together to form a polypeptide

Answer 1

Multiple amino acids undergo a condensation reaction, in which H is removed from the amine group and OH from the carboxyl group (H2O). From this a peptide bond is formed between amino acids forming a polypeptide

Question 2

Give a definition of the primary structure of a protein

Answer 2

The linear sequence of amino acids in a peptide or protein

Question 3

Describe how the secondary structure of a protein forms from the primary structure

Answer 3

Hydrogen bonding between primary structures causes secondary structures to form.
Alpha Helixes: a hydrogen bond is formed between the N−H group to the C=O group of the amino acid
Beta sheet: It consists of various beta strands linked by hydrogen bonds between adjacent strands. Three to ten amino acids are combined to create a beta-strand polypeptide.

Question 4

Describe how the tertiary structure of a protein forms from the secondary structure

Answer 4

Combination of alpha helixes and beta sheets. Due to r group interactions and provides 3D shape.
H bonds = maintain shape
Polar interactions = maintain shape
Disulphide bonds = further support as H not strong enough.

Question 5

Explain how the primary structure of a protein determines the functional shape of the protein

Answer 5

The initial amino acid sequencing determines the folding and intramolecular bonding between chains which ultimately determines the proteins 3D shape.

Question 6

Describe the structure of a globular protein

Answer 6

Globular proteins are folded such that their tertiary structure consists of the polar, or hydrophilic, amino acids arranged on the outside and the nonpolar, or hydrophobic, amino acids on the inside of the three-dimensional shape.

Question 7

Explain how the structure of a globular protein determines its function and properties

Answer 7

Due to their outer layer being hydrophilic this arrangement is responsible for the solubility of this protein in water.