The amino acid sequence of a portion of a polypeptide is
N...Cys-Pro-Ala-Met-Gly-His-Lys...C

What is the mRNA sequence encoding this polypeptide fragment? Use N to represent any nucleotide, Pu to represent a purine, and Py to represent a pyrimidine. Label the 5′ and 3′ ends of the mRNA.

Key Concepts

Genetic Code

The genetic code is a set of rules that defines how the sequence of nucleotides in DNA and RNA is translated into the amino acid sequence of proteins. Each amino acid is encoded by a specific sequence of three nucleotides, known as a codon. Understanding the genetic code is essential for determining the mRNA sequence that corresponds to a given polypeptide.

Transcription

Transcription is the process by which the information in a gene's DNA sequence is copied into messenger RNA (mRNA). During transcription, RNA polymerase synthesizes mRNA by pairing complementary RNA nucleotides with the DNA template strand. This process is crucial for producing the mRNA that encodes the polypeptide fragment in the question.

Codon-Amino Acid Relationship

The relationship between codons and amino acids is fundamental in molecular biology. Each codon in mRNA corresponds to a specific amino acid or a stop signal during protein synthesis. By knowing the amino acid sequence of a polypeptide, one can deduce the corresponding mRNA codons, which is necessary for answering the question about the mRNA sequence encoding the given polypeptide.