Question

n experiment to decipher the genetic code, a poly-AC mRNA (ACACACAC...) is synthesized. What pattern of amino acids would appear if this sequence were to be translated by a mechanism that reads the genetic code as a doublet without overlaps?

Answer 1

The pattern of amino acid will be of a polypeptide with a single type of amino acid. Generally translation of proteins depends on the triplet codon of bases,with complementary anti -codons of the tRNA. Thus A-U, C-G.

Therefore, in a doublet without overlaps of mRNA (ACACACAC) only one form of polypeptide chain of amino acids(UG UG UG UG) will be produced as shown below.

ACACACAC⇔UGUGUGUG.

Answer 2

The question lacks options, the options are:

A) Two different polypeptides would be produced, each one composed of a single type of amino acid.

B) The resulting polypeptide would be composed of two alternating types of amino acids.

C) The resulting polypeptide would be composed of a single type of amino acid.

D) Two different polypeptides would be produced, each one composed of two alternating types of amino acids.

The answer is C

Step-by-step explanation:

Genetic code consists of nuceleotide sequences which are read in order to synthesize a polypeptide (future protein). The mRNA which is produced by transcription of DNA is translated in the ribosome. The translation involves reading of the nucleotide sequence in the RNA molecule. The sequence is read as a doublet means that the nucleotide bases are read two at a time. Each two nuceleotides encodes a particular amino acid.

In the poly mRNA molecule with sequence (ACACACAC....), the nucleotides are read two at a time without overlaps i.e. without omitting or covering up any nucleotide base. This means that the nucleotides will be translated into an amino acid sequence (polypeptide) with only one type of amino acid (AC- AC - AC.....).