Answer

The diagram below is of a section of DNA.

(i) Complete the diagram by entering the letter for each base on the corresponding DNA strand. Thymine and Guanine are shown by the letters T & G.

A and C opposing T & G respectively

Image

[ 1 ]

(ii) State the name of the bases represented by the letters A & C.

C: Cytosine

A: Adenine

[ 1 ]

(iii) Identify the components of DNA represented by the letters X and Y.

X: Hydrogen bonds

Y: Sugar-Phosphate backbone (do not allow just 'backbone')

[ 2 ]

(iv) Nucleic bases are described as purines and pyrimidines. State which bases are purines and which are pyrimidines.

Purines: Adenine & Guanine

Pyrimindines: Thymine & Cytosine

[ 2 ]

(vi) Nucleic bases are sometimes referred to as nitrogenous bases. Explain this statement.

They contain Nitrogen

[ 1 ]

(vii) In the space below, draw and label an amino acid.

Image

Note: 'a' is not required

[ 2 ]

(viii) Amino acids are linked by a special bond to form the primary structure of a protein. Name this bond and state how the primary structure determines the nature of the final protein.

Name of bond: peptide

Primary structure: number, order, type (of) amino acids

[ 2 ]

[Total: 11 ]