The two gels illustrated contain dideoxynucleotide DNA-sequencing information for a wild-type segment and mutant segment of DNA corresponding to the N-terminal end of a protein. The start codon and the next five codons are sequenced. Identify the template and nontemplate strands of DNA.

Key Concepts

Template and Nontemplate Strands

In DNA, the template strand is the one that serves as a guide for RNA synthesis during transcription, while the nontemplate strand, also known as the coding strand, has the same sequence as the RNA produced (except for thymine being replaced by uracil). Identifying these strands is crucial for understanding how genetic information is transcribed and translated into proteins.

Dideoxynucleotide Sequencing

Dideoxynucleotide sequencing, or Sanger sequencing, is a method used to determine the nucleotide sequence of DNA. It involves incorporating dideoxynucleotides, which terminate DNA strand elongation, allowing for the generation of fragments of varying lengths that can be analyzed to reveal the sequence of the template strand. This technique is essential for comparing wild-type and mutant DNA segments.

Codons and Start Codon

Codons are sequences of three nucleotides in mRNA that correspond to specific amino acids during protein synthesis. The start codon, typically AUG, signals the beginning of translation and is crucial for the correct assembly of the protein. Understanding codons is vital for interpreting the genetic information encoded in the DNA sequence and its implications for protein function.