A section of mRNA transcribed from a eukaryotic gene that codes for a structural polypeptide is shown below:
mRNA: 5'- AUG - CCG - UGC - GUC - 3'
A point mutation occurred in the template DNA strand, resulting in the third mRNA codon changing from UGC (cysteine) to UUC (phenylalanine).
The genetic code lookup for the relevant codons is as follows:
AUG codes for MethionineCCG codes for ProlineUGC codes for CysteineUGU codes for CysteineUUC codes for PhenylalanineUUU codes for PhenylalanineName the type of covalent bond present in the primary structure of a protein that links successive amino acids.
Outline the role of RNA polymerase in the transcription of this mRNA molecule.
State the base sequence of the anticodon on the tRNA molecule that pairs with the mutated codon UUC.
Explain how a mutation that changes the third codon from UGC to UGU would affect the final tertiary structure of the protein. Refer to the degeneracy of the genetic code.
In contrast, a mutation changing UGC to UUC replaces cysteine (which forms covalent disulfide bridges) with phenylalanine (a hydrophobic amino acid). Explain how this substitution can alter the tertiary structure and biological activity of the protein.