Assuming the genetic code is a triplet, what effect would the addition or loss of two nucleotides have on the reading frame? The addition or loss of three, six, or nine nucleotides?

Verified step by step guidance

1. Understand that the genetic code is read in triplets, known as codons, each of which codes for a specific amino acid.
2. Recognize that adding or removing nucleotides in numbers not divisible by three (e.g., one or two nucleotides) will cause a frameshift mutation, altering the reading frame and potentially changing every subsequent codon.
3. Consider that the addition or loss of two nucleotides will shift the reading frame, leading to a completely different sequence of amino acids from the point of mutation onward.
4. Realize that adding or removing nucleotides in multiples of three (e.g., three, six, or nine nucleotides) will not cause a frameshift, as the reading frame remains intact, though it may result in the addition or deletion of one or more amino acids.
5. Conclude that while frameshift mutations can have drastic effects on protein function, the addition or loss of nucleotides in multiples of three may have less severe effects, depending on the specific amino acids involved.

Key Concepts

Reading Frame

The reading frame refers to the way nucleotides in DNA or RNA are grouped into codons, which are sets of three nucleotides that correspond to specific amino acids during protein synthesis. The reading frame is crucial because it determines how the sequence is interpreted by ribosomes. A shift in the reading frame can lead to entirely different amino acid sequences, potentially resulting in nonfunctional proteins.

Frameshift Mutation

A frameshift mutation occurs when nucleotides are added or deleted from the genetic sequence, altering the reading frame. If one or two nucleotides are added or lost, the entire downstream sequence is misread, leading to a completely different set of amino acids. In contrast, the addition or loss of three nucleotides typically results in the addition or loss of one amino acid without shifting the reading frame.

Codon and Genetic Code

A codon is a sequence of three nucleotides that encodes a specific amino acid or a stop signal during protein synthesis. The genetic code is the set of rules by which information encoded in genetic material is translated into proteins. Understanding codons is essential for grasping how mutations, such as those caused by nucleotide additions or deletions, can affect protein structure and function.