Why are well-defined reading frames critical in protein synthesis? A. Without a well-defined reading frame, the resulting protein would be transported to the cell surface. B. Without a well-defined reading frame, the ribosome is unable to bind to the mRNA. C. Without a well-defined reading frame, the peptide made from a given sequence could be completely different. D. Without a well-defined reading frame, the mRNA would be transcribed back into DNA.

The correct answer is option C. "Without a well-defined reading frame, the peptide made from a given sequence could be completely different".

Explanation:

In molecular biology, the reading frame is defined as the way a nucleotide sequence is divided in triplets, at which each group of three nucleotide (codons) is translated into an amino acid. Well-defined reading frames are critical in protein synthesis, because any change in the reading frame would result in a peptide completely different of the one desired. A clear example of the importance of a well-defined reading frame is seen in frameshift mutations, at which nucleotide insertions or deletions causes leads to the synthesis of a completely different and non functional protein.

Option (C).

Explanation:

Reading frames represent a way of reading the sequence of nucleotides in a DNA or RNA molecule into a set of non-overlapping, constitutive triplets.

These triplets are known as genetic codes or codons. There are total 64 codons, out of which 61 code for particular amino acids and three codons provide stop signaling.

So, if a reading frames change in a RNA molecule, it will lead to change in codon sequence and formation of a completely different peptide.

Thus, the correct answer is option (C).