Reading frame

Definition

A reading frame is a way of dividing the sequence of nucleotides in a DNA or RNA molecule into a set of consecutive, non-overlapping triplets. Each triplet, known as a codon, codes for a specific amino acid during protein synthesis.

5 Must Know Facts For Your Next Test

1. There are three possible reading frames for any given nucleotide sequence.
2. The correct reading frame is determined by the start codon (AUG) during translation.
3. A shift in the reading frame can result in a completely different sequence of amino acids, often leading to nonfunctional proteins.
4. Mutations that insert or delete nucleotides can cause frameshift mutations, altering the entire downstream amino acid sequence.
5. In eukaryotic cells, the reading frame is established in the cytoplasm when mRNA interacts with ribosomes.

Review Questions

• What determines the correct reading frame during translation?
• How can insertion or deletion mutations affect the reading frame?
• Why are frameshift mutations often more harmful than point mutations?

Related terms

Codon: A sequence of three nucleotides that together form a unit of genetic code in a DNA or RNA molecule.

Start Codon: The codon (AUG) that signals the start of translation and sets the reading frame.

Frameshift Mutation: A genetic mutation caused by insertions or deletions of nucleotides that change the reading frame.