An experiment by Khorana and his colleagues translated a synthetic mRNA containing repeats of the trinucelotide UUG.
How many reading frames are possible in this mRNA?

Verified step by step guidance

1. Understand the concept of a reading frame: A reading frame is a way of dividing a sequence of nucleotides in mRNA into consecutive, non-overlapping triplets (codons). Each codon specifies an amino acid during translation.
2. Recognize that mRNA is read in the 5' to 3' direction, and the reading frame depends on where translation starts. For a given sequence, there are three possible reading frames, depending on whether translation starts at the first, second, or third nucleotide.
3. Analyze the given mRNA sequence: The synthetic mRNA contains repeats of the trinucleotide UUG. This means the sequence is something like UUGUUGUUG... and so on.
4. Determine the reading frames: Starting at the first nucleotide (U), the first reading frame would be UUG, UUG, UUG... Starting at the second nucleotide (U), the second reading frame would be UGU, UGU, UGU... Starting at the third nucleotide (G), the third reading frame would be GUU, GUU, GUU...
5. Conclude that there are three possible reading frames in this mRNA sequence, as is the case for any mRNA sequence, regardless of its specific nucleotide composition.

Key Concepts

Reading Frames

A reading frame refers to the way nucleotides in mRNA are grouped into codons, which are sets of three nucleotides that correspond to specific amino acids. Since mRNA can be read in three different ways depending on where the reading starts, each starting point creates a different reading frame. This is crucial for understanding how genetic information is translated into proteins.

Codons

Codons are sequences of three nucleotides in mRNA that specify a particular amino acid during protein synthesis. The genetic code consists of 64 possible codons, which include 61 that code for amino acids and 3 that serve as stop signals. Understanding codons is essential for interpreting how sequences of mRNA translate into functional proteins.

Synthetic mRNA

Synthetic mRNA is artificially created RNA that can be designed to contain specific sequences of nucleotides. In the context of experiments, synthetic mRNA allows researchers to study the translation process and the effects of specific nucleotide sequences on protein synthesis. This is particularly relevant in experiments like those conducted by Khorana, which explore the fundamental aspects of genetic translation.