I began this series last week with a question about a DNA sequence that was published and reported to be one the first beta-lactamases to be found in Streptococcus pneumoniae. Mike has a great post about one of problems with this paper. I think the data themselves are awfully suspicious ...
Here's a fun puzzler for you to figure out. The blast graph is here: The table with scores is here, click the table to see a bigger image: And here is the puzzling part: Why is the total score so high? If you want to repeat this for yourself, go ...
Like 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 ...
Last year I wrote about an experiment where I compared a human mitochondrial DNA sequence to primate sequences in the GenBank. Since I wanted to know about the differences between humans, gorillas, and chimps, I used the Entrez query 'Great Apes' to limit my search to a set of sequences ...
As many of you know, I'm a big fan of do-it-yourself biology. Digital biology, the field that I write about, is particularly well-suited to this kind of fun and exploration. Last week, I wrote some instructions for making a phylogenetic tree from mitochondrial genomes. This week, we'll continue our analysis ...
Many of you might take this for granted, and I know it seems amazing today, but I when first started teaching, our access to scientific literature was pretty limited. I could go to the UW and use Grateful Med to search Medline, but we didn't have anything like it at ...
Last 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 ...
tags: How does grass grow in the extremely hot soils of Yellowstone National Park? The quest continues. Read part I, part II, part III, and part IV to see how we got here. And read onward to see where will we go. In our last episode, I discovered a new ...
How does grass grow in the extremely hot soils of Yellowstone National Park? Could a protein from a virus help plants handle global warming? Okay, that second sentence is wild speculation, but we will try to find the answer to our mystery by aligning our protein sequence to a sequence ...
During 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 ...
"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 ...
The 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 ...
I've had some requests for some more molecular puzzles since the last one that I posted (see A DNA puzzle ). One person liked it so much he even blogged about it. So, here's one for you to chew on over the weekend. This puzzle is a variation of an ...
Today, we're going to look for rainbows in double-stranded DNA and see what they can tell us about DNA structure. First, we're going to get a structure for a double-stranded molecule of DNA and open it in Cn3D. 1K9L If you want to do this at home and you haven't ...
In last week's episode, your assignment was to think of an interesting plant trait and find a description about a gene, related to that trait, by searching PubMed. Since coming up with an interesting trait might be a challenge for some people, let's think about how to approach this step ...
Why do I love Cn3D? Let me count the ways. What does Cn3D do? ( Hint: say "Cn3D" out loud). Seriously, Cn3D is a program that draws lovely pictures of molecular structures by using experimental data from techniques like X-ray crystallography and nuclear magnetic resonance spectroscopy. Surprisingly ( to some) ...
We'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 ...
Last Friday, we had another in the series of weird DNA structures. (You can see the first here). I asked the audience to identify the unusual feature in this molecule. Here's the first picture: tags: Here's the answer: Steve L. guessed it correctly. This is not just DNA, it's a ...
If we compare sections 1, 2, and 3, we see that section 2 matches very well in a number of different samples, and that there are differences between the sequences in sections 1 and 3. We also learn something about the people who did the experiment. At first it appears ...
Last 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 ...
During the past few Fridays (or least here and here), we've been looking at a paper that was published from China with some Β-lactamase sequences that were supposedly from Streptococcus pneumoniae. The amazing thing about these particular sequences is that Β-lactamase has never been seen in S. pneumoniae before, making ...
Welcome 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 ...
If you look below the fold, you can see two molecules locked in a tight embrace. These molecules or their closely related cousins can be found in any cell because their ability to evolve is slowed by their need to interact with each other in the right way. In an ...
This is a fun puzzle. The pink molecule is a protein and the other molecule is a nucleic acid. If I gave you the amino acid sequence of this protein, or the nucleotide sequence of this nucleic acid, what is the probability of finding a similar sequence in a different ...
Last week I posted an image with two molecules ( below the fold), one protein and one nucleic acid, and asked you about the probability of finding similar molecules in different species. You gave me some interesting answers. DAG made me clarify my question by asking what I meant by ...
Let's play anomaly! Most of this week, I've written about the fun time I had playing around with NCBI's Blink database and finding evidence that at least one mosquito, Aedes aegypti, seems to have been infected at some point with a plant paramyxovirus and that the paramyxovirus left one of ...
I found it in the MeSH database. Really! Looking for a quick answer? Don't ask a scientist It doesn't take long to realize that scientists can spend countless hours debating the meaning of words. Our very own ScienceBlogs is a great example, just look at the many ways we can ...
and what is the volume of the sea? This sounds a bit like the beginning of a poem but it's really the answer to the question we posed last week on a Digital Biology Friday. We can see, in the sequence window, that two strands are both labeled 5' on ...
