Faculteit der Natuurwetenschappen, Wiskunde en Informatica

Zoek in de site...

Murder at the Airport

Exercise 4:

Click on the line to get more details about the results. The following screen appears:


This screen gives you the so-called hitlist, the list of protein sequences found in the SwissProt database that are similar to suspect1. From left to right, every line shows the following output for each one of the hits:

  • Nr: The number of the result. Number 1 always shows the best hit, and so on
  • ID: This is the code of the protein sequence from the database. The first part of the code (casa1) is the name of the protein, the second part contains the (shortened) name of the organism, in this case bovine.
  • Coverage: The coloured line shows which part of your query sequence (suspect1) matches the database sequence (the grey background). On the first line, you can see that your query sequence matches the casa1_bovin sequence over its entire length.
  • Description: a brief description of the database sequence matching your query
  • Hsps, Bitscore en E-value: Values calculated by BLAST to give you an idea about the reliability of the result. The best hit is always on top.

Exercise 5:

Let’s have a look at the first hit, casa1_bovin. Click on the coloured bar, then on the two-coloured bar. Analyze the results.


As you can see, the sequence of suspect1 is 100% identical to the sequence of casa1_bovin, the alpha-S1-casein protein (all 199 amino acids are identical). Thus, you have successfully identified one of the four proteins. You now see a so-called alignment of the two amino acid sequences. Q (query) is the sequence that you have entered, in this case suspect1. S is the protein sequence from the database that looks most like suspect1, in this case casa1_bovin. The line between these two sequences contains the letters of all amino acids that are identical in Q and S. If not all amino acids are identical, you will see gaps.

Click on casa1_bovin to go to the database record and see all known data about this protein, in order to find out if this protein could be involved in the death of the tourist.


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