Har Gobind Khorana and his colleagues performed numerous experiments translating synthetic mRNAs. In one experiment, an mRNA molecule with a repeating UG dinucleotide sequence was assembled and translated.

If the genetic code were overlapping rather than nonoverlapping, how would the result of this experiment be different?

Verified step by step guidance

1. Understand the concept of overlapping vs. nonoverlapping genetic code. In a nonoverlapping code, each nucleotide is part of only one codon, whereas in an overlapping code, a single nucleotide could be part of multiple codons.
2. Consider the mRNA sequence with a repeating UG dinucleotide: UGUGUGUG... In a nonoverlapping code, this sequence would be read as UGU, GUG, UGU, GUG, etc.
3. In an overlapping code, the reading frame would shift by one nucleotide for each new codon. For example, the sequence could be read as UGU, GUG, UGU, GUG, etc., but also as GUG, UGU, GUG, UGU, etc.
4. Analyze how the overlapping reading frame would affect the resulting polypeptide. Each nucleotide would contribute to multiple codons, potentially leading to a different sequence of amino acids.
5. Reflect on the implications of overlapping codes on genetic diversity and protein synthesis. Overlapping codes could result in more complex and varied proteins from a single mRNA sequence.

Key Concepts

Genetic Code

The genetic code is a set of rules that defines how the sequence of nucleotides in mRNA is translated into amino acids, the building blocks of proteins. It consists of codons, which are groups of three nucleotides that correspond to specific amino acids. Understanding the genetic code is essential for interpreting how mRNA sequences dictate protein synthesis.

Overlapping vs. Nonoverlapping Code

In a nonoverlapping genetic code, each nucleotide is part of only one codon, meaning that the reading frame shifts after every three nucleotides. In contrast, an overlapping code allows for nucleotides to be shared between adjacent codons, potentially leading to different amino acid sequences. This distinction is crucial for predicting how changes in mRNA sequences affect protein translation.

Translation Process

Translation is the process by which ribosomes synthesize proteins based on the sequence of mRNA. During translation, tRNA molecules bring specific amino acids to the ribosome, matching their anticodons with the mRNA codons. The way the genetic code is structured—overlapping or nonoverlapping—directly influences the resulting protein's amino acid sequence and function.