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. Write the DNA sequence of both alleles, including strand polarity.

Key Concepts

Dideoxynucleotide Sequencing

Dideoxynucleotide sequencing, also known as 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. By analyzing these fragments through gel electrophoresis, researchers can deduce the sequence of the original DNA strand based on the size of the fragments.

Codons and Genetic Code

Codons are sequences of three nucleotides in DNA or RNA that correspond to specific amino acids or stop signals during protein synthesis. The genetic code is universal and dictates how sequences of nucleotides are translated into proteins. Understanding codons is essential for interpreting the DNA sequence and predicting the resulting protein structure and function.

Strand Polarity

Strand polarity refers to the orientation of the DNA strands, which are antiparallel and have distinct 5' and 3' ends. The 5' end has a phosphate group, while the 3' end has a hydroxyl group. This polarity is crucial for DNA replication and transcription, as enzymes that synthesize DNA and RNA can only add nucleotides to the 3' end of a growing strand, influencing how sequences are read and written.