"By night all cats are gray" - Miguel Cervantes in Don Quixote
I've always liked Siamese cats. Students do, too. "Why Siamese cats wear masks" is always a favorite story in genetics class. So, when I opened my January copy of The Science Teacher, I was thrilled to see an article on Siamese cat colors and proteins AND molecular genetics (1). In the article, the authors (Todd and Kenyon) provide some background information on the enzymatic activity of tyrosinase and compare it to the catechol oxidase that ... Read more
We've been fans of the Molecule of the Month series by David Goodsell, for many years. Not only is Dr. Goodsell a talented artist but he writes very clear descriptions of the ways molecules like proteins, RNA, and DNA work together and function inside a cell.
To learn about proteins and their activities, I like to go directly to the Molecule of the Month page, where I can find a list of articles organized by molecule type and name. Many of these articles can also be downloaded in a PDF format.
A really nice of his articles is that he includes PDB IDs ... Read more
A few weeks back, we published a review about the development and role of the human reference genome. A key point of the reference genome is that it is not a single sequence. Instead it is an assembly of consensus sequences that are designed to deal with variation in the human population and uncertainty in the data. The reference is a map and like a geographical maps evolves though increased understanding over time.
A key concept in science is molecular scale. DNA is a fascinating molecule in this regard.
While we cannot "see" DNA molecules without the aid of advanced technology, a full length DNA molecule can be very long. In human cells, other than sperm and eggs, six billion base pairs of DNA are packaged into 22 pairs of chromosomes, plus two sex chromosomes. Each base pair is 34 angstroms in length (.34 nanometers, or ~0.3 billionths of a meter), so six billion base pairs (all chromosomes laid out head to toe) form a chain that's two-meters long. If we could hang this DNA chain from a hook, it ... Read more
Organisms with linear chromosomes have to solve the problem that DNA replication makes them shorter. This is due to the fact that DNA polymerase can only add bases to the terminal 3'-OH of a DNA chain. The DNA replication initiation complex uses RNA primers to provide the initial 3'-OH and ... Read more
Getting an accurate genome sequence requires that you collect the data at least twice argue Robasky, Lewis, and Church in their recent opinion piece in Nat. Rev. Genetics .
The DNA sequencing world kicked off 2014 with an audacious start. Andrew Pollack ran an article in the New York Times implying that 100,000 genomes will be the new norm in human genome sequencing projects . The article focused on a collaboration between Regeneron and Geisinger Health in which they plan to sequence the exomes (the ~2% of the genome that encodes proteins and some non-coding RNA) of 100,000 individuals ... Read more
This morning I attended a "bloggers-only" conference call with Dr. Eric Green and the folks from the NIH Human Genome Research Institute (NHGRI) to hear about NHGRI's new strategic plan. The new plan represents a shift away from viewing the genome through a lens marked "for research use only" and towards the goal of making the genome useful as a clinical tool. As a consequence, we will see a greater emphasis on funding activities that support clinical work. For example, it's not always clear how variations in the genome are related to disease. NHGRI might fund projects that help sort and ... Read more
One of my hobbies lately has been to get either RNA seq or microarray data from GEO and do quick analyses. Not only is this fun, I can find good examples to use for teaching biology.
One of these fun examples comes from some Arabidopsis data. In this experiment, some poor little seedlings were taken out of their happy semi-liquid culture tubes and allowed to dry out. This simulated drought situation isn't exactly dust bowls and hollow-eyed farmers, but the plants don't know that and most likely respond in a similar way. ... Read more
You might think the coolest thing about the Next Generation DNA Sequencing technologies is that we can use them to sequence long-dead mammoths, entire populations of microbes, or bits of bone from Neanderthals.