Digital Biology Fridays
sporte | August 25, 2006Like biology, all bioinformatics is based on the idea that living things shared a common ancestor. I have posted, and will post other articles that test that notion, but for the moment, we're going to use that idea as a starting point in today's quest.
If we agree that we have a common ancestor, then we can use that idea as a basis to ask some interesting questions about our genomes. For, example, we know that genomes change over time - we've looked at single nucleotide changes here and here, and we've seen that large chunks of DNA can move around here.
So, it's interesting to consider…
sporte | August 18, 2006The past few Fridays, we've been comparing human mitochondrial DNA with the mitochondrial DNA of different apes.
We started doing this here, where you can find directions for getting started.
And, we've found some interesting things.
In this installment, we found that humans have practically an entire mitochondrial genome stuck in chromosome 17.
Last week, we found that human mitochondrial DNA is more similar to that of chimpanzees than to gorillas. We found that 90.6% of the bases in human mitochondrial DNA match bases in the Bonobo chimp and 90.7% match bases in the Chimpanzee.
This…
sporte | August 11, 2006During these past couple of weeks, we've been comparing mitochondrial DNA sequences from humans and great apes, in order to see how similar the sequences are.
Last week, I got distracted by finding a copy of a human mitochondrial genome, that somehow got out of a mitochondria, and got stuck right inside of chromosome 17! The existence of this extra mitochondrial sequence probably complicates some genetic analyses. One of my readers also asked an interesting question about whether apes have a similar mitochondrial sequence in their equivalent of chromosome 17, and how it compares. We will…
sporte | August 4, 2006Last week, we decided to compare a human mitochondrial DNA sequence with the mitochondrial sequences of our cousins, the apes, and find out how similar these sequences really are.
The answer is: really, really, similar.
And you can see that, in the BLAST graph, below the fold.
A quick glance shows that the ape with the most similar mitochondrial sequence is Pan paniscus, the pigmy chimpanzee. Next, is Pan troglodytes, the chimp that we see in movies, and last we have Gorilla gorilla.
Then we have a really curious, and unexpected, matching sequence.
Click the picture to see a larger…
sporte | July 28, 2006We've had a good time in the past few last weeks, identifying unknown sequences and learning our way around a GenBank nucleotide record. To some people, it seems that this is all there is to doing digital biology. They would, of course, be wrong.
We can do much, much more than identifying DNA sequences and obtaining crucial information, like who left their DNA behind on that little blue dress.
Today, we're going to a deeper question about who we are and who are our relatives.
Drumroll, okay, here it comes:
How similar are DNA sequences between humans and apes?
Your assignment is to find…
sporte | July 21, 2006"Hey Rocky, watch me pull a rabbit out of my hat!"
I realized that I should add just a bit more information to last answer on gene identification, so here it is.
After the last installment, Diego commented:
but still you do not know exactly what part of your DNA sequence is matching to the annotated protein.
Ahh, but we do.
And I was negligent in not showing you.
There are multiple ways to view the GenBank record that we arrived at while following links from our matching sequence.
A very handy way, especially if you're looking at where sequences align to a larger subject sequence, like…
sporte | July 21, 2006Welcome back!
If you've just joined us, we're in the middle of a quest to find the identity of an unknown nucleotide sequence. To summarize our results so far, we used this sequence to do a blastn search of GenBank, using all the default settings at the NCBI. You can see the beginning of the project here.
And we had some rather curious results.
It appeared that our sequence matched sequences from very diverse organisms, like Dengue virus, E. coli, and Simian Immunodeficiency virus. Very strange!
There was another curious word, too, that appeared in the descriptions for each of the results…
sporte | July 14, 2006Last week, we embarked on an adventure with BLAST.
BLAST, short for Basic Alignment Search Tool, is a collection of programs, written by scientists at the NCBI (1) that are used to compare sequences of proteins or nucleic acids. BLAST is used in multiple ways, but last week my challenge to you, dear readers, was to a pick a sequence, any sequence, from a set of 16 unknown sequences and use BLAST to identify that sequence.
This week, we'll examine the results.
I did the experiment, too, with a completely different unknown sequence that's pasted below. This sequence is not part of the data…