1.6 Proteins

Question 1

What chemical groups are attached to the central carbon atom in an amino acid?

Answer 1

-amino group
-carboxyl group
-hydrogen atom
-R (side) group

Question 2

What is a peptide?

Answer 2

two or more amino acids joined together by peptide bonds

Question 3

What is a protein?

Answer 3

long chains of amino acids held together by peptide bonds

Question 4

Define the primary structure of a protein?

Answer 4

the sequence of amino acids linked together to form a polypeptide chain

Question 5

what does the order of deoxyribonucleotide bases in a gene determine?

Answer 5

the amino acid sequence of a particular protein

Question 6

What happens in the secondary structure of the protein?

Answer 6

the protein or polypeptide is given the two-dimensional form of an alpha-helix or a beta-pleated sheet

Question 7

What happens in gobbler proteins such as enzymes?

Answer 7

the long chain of amino acids becomes folded into a three-dimensional functional shape or tertiary structure

Question 8

What bonds are found in the tertiary structure of proteins?

Answer 8

-disulphide bonds
-ionic bonds
-hydrogen bonds

Question 9

What is the test for proteins?

Answer 9

Biurets test

Question 10

How is the burets test performed?

Answer 10

-add equal volumes of sodium hydroxide and the sample
-add a few drops of very dilute copper(II) sulphate solution and mix gently
-purple colourisation means a positive indication for peptide bonds