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.
What is the sequence of the resulting polypeptide?

Verified step by step guidance

1. Understand the problem: The mRNA sequence consists of repeating UG dinucleotides. Translation involves reading the mRNA sequence in codons (groups of three nucleotides) to determine the corresponding amino acids in the polypeptide chain.
2. Break the repeating UG sequence into codons: Since the sequence is repeating UG (UGUGUG...), the codons formed will alternate between UGU and GUG. This is because translation reads the mRNA in groups of three nucleotides.
3. Determine the amino acids corresponding to each codon: Use the genetic code table to find the amino acids. For example, UGU codes for cysteine (Cys), and GUG codes for valine (Val).
4. Analyze the pattern of the polypeptide sequence: Since the mRNA sequence alternates between UGU and GUG, the resulting polypeptide will alternate between cysteine (Cys) and valine (Val).
5. Conclude the sequence of the polypeptide: The polypeptide will consist of a repeating pattern of cysteine (Cys) and valine (Val), corresponding to the alternating codons in the mRNA sequence.

Key Concepts

mRNA and Codons

Messenger RNA (mRNA) is a type of RNA that carries genetic information from DNA to the ribosome, where proteins are synthesized. The mRNA sequence is read in sets of three nucleotides called codons, each of which corresponds to a specific amino acid. Understanding how codons are formed from nucleotide sequences is essential for predicting the resulting polypeptide.

Translation Process

Translation is the process by which ribosomes synthesize proteins using the information encoded in mRNA. During translation, the ribosome reads the mRNA codons and matches them with the appropriate transfer RNA (tRNA) molecules that carry specific amino acids. This process results in the formation of a polypeptide chain, which eventually folds into a functional protein.

Genetic Code

The genetic code is a set of rules that defines how sequences of nucleotides in mRNA are translated into amino acids. It consists of 64 codons that specify 20 different amino acids, with some amino acids being encoded by multiple codons. Understanding the genetic code is crucial for determining the sequence of the resulting polypeptide from a given mRNA sequence.