Forward and Reverse DNA Sequence Editing and Alignment

Forward and Reverse DNA Sequence Editing Tutorial

Introduction to DNA Sequences

• The tutorial focuses on editing and aligning forward and reverse DNA sequences for BLAST analysis. It emphasizes the importance of having AB1 files from sequencing technology.

Analyzing the Forward Sequence

• The biotic software is used to visualize the chromatogram of the forward sequence, allowing assessment for contamination and ambiguous bases. Users are encouraged to scroll through the sequence for a thorough review.

• Initial observations indicate that up to 540 bases in the forward sequence are correct, while there are issues with bases at both ends, particularly noting that 31 bases at the beginning contain ambiguities.

Editing the Forward Sequence

• The user deletes incorrect bases from both ends: 31 ambiguous bases at the start and any data beyond 540 correct bases at the end, ensuring a clean sequence for further analysis.

Transitioning to Reverse Sequence Editing

• Similar steps are taken with the reverse sequence; it starts with identifying incorrect bases (initially noted as 51). After careful examination, it is determined that 517 bases are more accurate for editing purposes.

• The user marks positions where edits need to be made, deleting incorrect sections just like in the forward sequence process. This ensures consistency across both sequences.

Combining Forward and Reverse Sequences

• To align both sequences in parallel directionality, users utilize a reverse complement option within their software tools, converting the reverse sequence accordingly. This step is crucial for subsequent analyses.

• After combining both sequences by pasting them together in one file, users prepare this aligned sequence for future reference and BLAST analysis by copying it into Microsoft Word or similar applications.

Final Analysis Results

• Upon conducting a BLAST analysis on the combined aligned sequence, results show a perfect match with tumor protein p53 mRNA indicating an E-value of 0.0 and percentage identity of 100%. This confirms successful alignment and accuracy of edited sequences before concluding this segment of work.