In the course of the Drosophila melanogaster genome project, the following genomic DNA sequences were obtained. Try to assemble the sequences into a single contig.

5' TTCCAGAACCGGCGAATGAAGCTGAAGAAG 3'
5' GAGCGGCAGATCAAGATCTGGTTCCAGAAC 3'
5' TGATCTGCCGCTCCGTCAGGCATAGCGCGT 3'
5' GGAGAATCGAGATGGCGCACGCGCTATGCC 3'
5' GGAGAATCGAGATGGCGCACGCGCTATGCC 3'
5' CCATCTCGATTCTCCGTCTGCGGGTCAGAT 3'

Go to the URL provided in Problem 14, and using the sequence you have just assembled, perform a blastn search in the 'Nucleotide collection (nr/nt)' database. Does the search produce sequences similar to your assembled sequence, and if so, what are they? Can you tell if your sequence is transcribed, and if it represents protein-coding sequence? Perform a tblastx search, first choosing the 'Nucleotide collection (nr/nt)' database and then limiting the search to human sequences by typing Homo sapiens in the organism box. Are homologous sequences found in the human genome? Annotate the assembled sequence.

Key Concepts

Genome Assembly

Genome assembly is the process of piecing together short DNA sequences into longer contiguous sequences, known as contigs. This is crucial in genomics, especially when working with fragmented data from sequencing projects. The goal is to reconstruct the original genome as accurately as possible, which involves aligning overlapping sequences and resolving ambiguities.

BLAST (Basic Local Alignment Search Tool)

BLAST is a bioinformatics tool used to compare an input sequence against a database of sequences to find regions of similarity. The 'blastn' search specifically compares nucleotide sequences, helping to identify homologous sequences across different organisms. This tool is essential for determining the functional and evolutionary relationships of genes and can indicate whether a sequence is transcribed or protein-coding.

Homologous Sequences

Homologous sequences are DNA, RNA, or protein sequences that share a common ancestry, often due to evolutionary processes. In the context of the question, identifying homologous sequences in the human genome can provide insights into gene function and conservation across species. This is important for understanding the biological significance of the assembled sequence and its potential role in human genetics.