Proteins

Question 1

Structure of Transport Proteins

Answer 1

-Contain hydrophobic and hydrophilic amino acids.

-So it folds to form a channel.

Question 2

Structure of structural proteins.

Answer 2

Long polypeptide chains lying parallel to each other.

With crosslinks between them.

Question 3

Role of structural proteins

Answer 3

Provide support to animal cells

Question 4

Properties of globular enzymes

Answer 4

-Roughly spherical due to tight folding of polypeptide chains

-Soluble

Question 5

Roles of globular enzymes

Answer 5

-Metabolism, breaking down food.

-Synthesising larger molecules.

Question 6

Which molecule and bond does the condensation reaction of two amino acids form?

Answer 6

-Dipeptide

-Peptide bond

Question 7

What is the chain of more than two amino acids bonded together with peptide bonds called?

Answer 7

Polypeptide chain

Question 8

Groups contained within Amino Acids

Answer 8

-Amine group (NH2)

-Carboxyl group (COOH)

-R group

Question 9

Globular Protein structure

Answer 9

-specific 3D shape

-tertiary and quaternary structure

-FOLD SO HYDROPHILIC GROUPS ARE ON THE OUTSIDE, HYDROPHOBIC ON THE INSIDE.

Question 10

Describe the formation of a dipeptide.

Answer 10

A condensation reaction between two amino acids.

One molecule of water is released

A peptide bond is formed between the adjacent amine group and carboxyl group of the amino acids.

Question 11

What is the primary structure of proteins?

Answer 11

The order of amino acids in a polypeptide chain, joined together by peptide bonds.

Question 12

What is the secondary structure of proteins?

Answer 12

The folding or coiling of the polypeptide chain into alpha helices or beta pleated sheets, held together by Hydrogen bonds.

Question 13

What is the tertiary structure of proteins?

Answer 13

The overall 3D shape of a single polypeptide chain, formed when the secondary structure folds further.

It is maintained by bonds within the R groups of amino acids.

Question 14

What is the quaternary structure of proteins?

Answer 14

The structure formed when multiple polypeptide chains are held together by bonds to form a functional protein.

Question 15

Which bonds may be present within the tertiary and quaternary structure of proteins?

Answer 15

Hydrogen bonds

Ionic bonds

Disulphide bridges

Question 16

Describe the properties of disulphide bridges

Answer 16

Very strong

Split using reducing agents

Found anywhere where there are two Sulphur atoms

Question 17

Describe the Biuret test for the presence of proteins within a sample.

Answer 17

Add Biuret reagent to the food sample.

For a positive result, the light blue solution will change colour to violet.