A portion of a polypeptide contains the amino acids Trp-Lys-Met-Ala-Val. Write the possible mRNA and template-strand DNA sequences. (Hint: Use A/G and T/C to indicate that either adenine/guanine or thymine/cytosine could occur in a particular position, and use N to indicate that any DNA nucleotide could appear.)

Verified step by step guidance

1. span>Identify the codons for each amino acid in the polypeptide sequence: Trp (Tryptophan), Lys (Lysine), Met (Methionine), Ala (Alanine), and Val (Valine).
2. span>Trp is encoded by the codon UGG. Lys is encoded by AAA or AAG. Met is encoded by AUG. Ala is encoded by GCU, GCC, GCA, or GCG. Val is encoded by GUU, GUC, GUA, or GUG.
3. span>Write the possible mRNA sequences using the identified codons: UGG for Trp, AAA/AAG for Lys, AUG for Met, GCU/GCC/GCA/GCG for Ala, and GUU/GUC/GUA/GUG for Val.
4. span>Determine the template-strand DNA sequences by replacing each mRNA nucleotide with its complementary DNA nucleotide: A with T, U with A, G with C, and C with G.
5. span>Use A/G and T/C to indicate positions where either adenine/guanine or thymine/cytosine could occur, and use N to indicate any nucleotide could appear, based on the degeneracy of the genetic code.

Key Concepts

Genetic Code

The genetic code is a set of rules that defines how the sequence of nucleotides in DNA and RNA corresponds to the sequence of amino acids in proteins. Each amino acid is encoded by a specific triplet of nucleotides called a codon. Understanding the genetic code is essential for translating polypeptide sequences back into their corresponding mRNA and DNA sequences.

Transcription

Transcription is the process by which the information in a DNA sequence is copied into a complementary RNA sequence. During this process, RNA polymerase synthesizes mRNA from the DNA template strand, replacing thymine (T) with uracil (U). This concept is crucial for determining the mRNA sequence from the given polypeptide.

Complementary Base Pairing

Complementary base pairing refers to the specific pairing of nitrogenous bases in nucleic acids: adenine (A) pairs with thymine (T) in DNA and uracil (U) in RNA, while guanine (G) pairs with cytosine (C). This principle is fundamental for deducing the template DNA strand from the mRNA sequence, as it ensures accurate pairing during transcription and replication.