A DNA sequence encoding a five-amino acid polypeptide is given below.
...ACGGCAAGATCCCACCCTAATCAGACCGTACCATTCACCTCCT...
...TGCCGTTCTAGGGTGGGATTAGTCTGGCATGGTAAGTGGAGGA...

Give the polypeptide sequence, and identify the N terminus and C terminus.

Verified step by step guidance

1. Identify the coding strand of the DNA sequence. The coding strand is the one that is not used as a template for transcription and is usually given in the 5' to 3' direction.
2. Transcribe the coding strand into mRNA by replacing each thymine (T) with uracil (U).
3. Divide the mRNA sequence into codons, which are groups of three nucleotides.
4. Use the genetic code to translate each mRNA codon into its corresponding amino acid. Remember that the translation starts at the start codon (AUG) and continues until a stop codon is reached.
5. Determine the N terminus and C terminus of the polypeptide. The N terminus is the start of the polypeptide chain, corresponding to the first amino acid translated, and the C terminus is the end of the chain, corresponding to the last amino acid before the stop codon.

Key Concepts

DNA and RNA Transcription

DNA sequences are transcribed into messenger RNA (mRNA) during the process of transcription. This involves the synthesis of an RNA strand complementary to the DNA template, which carries the genetic information needed for protein synthesis. Understanding this process is crucial for translating DNA sequences into polypeptide sequences.

Translation and Amino Acids

Translation is the process by which the mRNA sequence is decoded to synthesize a polypeptide chain, which is a sequence of amino acids. Each set of three nucleotides (codon) in the mRNA corresponds to a specific amino acid. Recognizing the codon-amino acid relationship is essential for determining the final polypeptide sequence from the given DNA.

Polypeptide Structure: N Terminus and C Terminus

Polypeptides have distinct ends known as the N terminus and C terminus. The N terminus is the end of the polypeptide with a free amino group, while the C terminus has a free carboxyl group. Identifying these termini is important for understanding the orientation and functional properties of the polypeptide.