Question

Why is redundancy built in the DNA code? Can a triplet codon for more than one amino acid or can amino acids be synthesized by more than one triplet of codons? How many codons code for 20 amino acids?

Why does mRNA have to be processed in eukaryotes and what does involve?

What translates the DNA message and how? Explain what tRNA does. How is it possible to have 45 tRNA but 61 mRNA to code for the same amino acids?

Explain how a ribosome works to generate a protein. Be sure to start with 2 ribosomal subunits coming together, and include the A,P,E sites in your explanation.

Answer 1

Redundancy in case of genetic code means that an amino acid is coded by ore than one codon. There are 64 codons that code for only 20 amino acids. This is a good thing because if there is a small mistake during transcription, there is a chance that through the redudancy similar codons could both code for the same amino acid. So even though there was a mistake in the base pair sequence, the amino acid sequence may be unaffected.

Yes a triplet codon can code for more than 1 amino acid.

64 codons code for 20 amino acids.

RNA processing in eukaryotes include capping, polyadenylation and splicing.

Capping is a process of in which modification of the 5’ ends takes place. Methylated guanisine is added to the 5‘ end of the RNA. The cap has four functions. It regulates nuclear export of RNA, it prevents degradation by exonucleases, it helps in promoting translation, it promotes excision of 5’ intron.

Polyadenylation is the addition of several adenosine nucleotides to the 3’ end of mRNAs called poly A tail. It also protects the mRNA from enzymatic degradation on the 3’ end, helps in nuclear export and translation.

Splicing is a process in which small interrupting sequences called introns are removed and the newly formed RNA is edited to form a final matured RNA.