Difference between revisions of "Jwoodlee Week 3"

Revision as of 18:34, 21 September 2015

Electronic Lab Notebook

ssh into my.cs.lmu.edu using your username, and enter your password.

Complement of a Strand

locate the file in ~dondi/xmlpipedb/data, and enter the following command:

cat prokaryote.txt | sed “y/actg/tgac”

This will yield prokaryote.txt’s complementary DNA strand.

Reading Frames

These sets of commands are more complicated than Complement of a Strand. This is essentially what I had to accomplish:

take sequence file, replace the t’s with u’s, break up the sequence into groups of 3, use genetic-code.sed as the translation “chart”, and then eliminate extra nucleotides if there are any. For the different reading frames I will just delete the first one or two nucleotides

After lots of googling I came up with this basic outline in terminal:

cat prokaryote.txt | sed "s/t/u/g" | sed "s/.../& /g" | sed -f genetic-code.sed

For different reading frames, insert sed “s/^.//g” or "s/^..//g" after prokaryote.txt, and of course in order to use a different DNA sequence prokaryote.txt would be different. The following commands will be written exactly and should return the correct output. Enter these commands into terminal after navigating to nfs/home/dondi/xmlpipedb/data/.

+1
cat prokaryote.txt | sed "s/t/u/g" | sed "s/.../& /g" | sed -f genetic-code.sed | sed "s/[acug]//g"

+2
cat prokaryote.txt | sed "s/^.//g" | sed "s/t/u/g" | sed "s/.../& /g" | sed -f genetic-code.sed | sed "s/[acug]//g"

+3 
cat prokaryote.txt | sed "s/^..//g" | sed "s/t/u/g" | sed "s/.../& /g" | sed -f genetic-code.sed | sed "s/[acug]//g"

In order to do these frames, I transcribed the DNA using sed "y///" and then reversed them in order to translate them from the proper side. (5' --> 3')

-1
cat prokaryote.txt | sed "y/actg/tgac/" | rev | sed "s/t/u/g" | sed "s/.../& /g" | sed -f genetic-code.sed | sed "s/[acug]//g"

-2
cat prokaryote.txt | sed "y/actg/tgac/" | rev | sed "s/t/u/g" | sed "s/^.//g" | sed "s/.../& /g" | sed -f genetic-code.sed | sed "s/[acug]//g" 

-3
cat prokaryote.txt | sed "y/actg/tgac/" | rev | sed "s/t/u/g" | sed "s/^..//g" | sed "s/.../& /g" | sed -f genetic-code.sed | sed "s/[acug]//g" 

Checked with Expasy translation tool.

XMLPipeDB Match Practice

For your convenience, the XMLPipeDB Match Utility (xmlpipedb-match-1.1.1.jar) has been installed in the ~dondi/xmlpipedb/data directory alongside the other practice files. Use this utility to answer the following questions:

1. What Match command tallies the occurrences of the pattern GO:000[567] in the 493.P_falciparum.xml file?
   • How many unique matches are there?
   • How many times does each unique match appear?
2. Try to find one such occurrence “in situ” within that file. Look at the neighboring content around that occurrence.
   • Describe how you did this.
   • Based on where you find this occurrence, what kind of information does this pattern represent?
3. What Match command tallies the occurrences of the pattern \"Yu.*\" in the 493.P_falciparum.xml file?
   • How many unique matches are there?
   • How many times does each unique match appear?
   • What information do you think this pattern represents?
4. Use Match to count the occurrences of the pattern ATG in the hs_ref_GRCh37_chr19.fa file (this may take a while). Then, use grep and wc to do the same thing.
   • What answer does Match give you?
   • What answer does grep + wc give you?
   • Explain why the counts are different. (Hint: Make sure you understand what exactly is being counted by each approach.)

BIOL 367, Fall 2015, User Page, Team Page