DNA structures

by Todd Smith

Scale, proportion, and quantity belong to one of the cross cutting concepts in the next generation science standards (NGSS). According to Volume 2 of the NGSS, "in engineering, no structure could be conceived much less constructed without the engineer's precise sense of scale." The authors go on to note that scale and proportion are best understood using the scientific practice of working with models.

When scientists and engineers work with these concepts at a molecular scale, new kinds of technologies can be created to advance our understanding of ... Read more

by Todd Smith

April 25th (4/25) is national DNA day. Digital World Biology™ is celebrating by sharing some of our favorite structures of DNA. We created these photos with Molecule World™ a new iPad app for viewing molecular structures.

Update: These same ... Read more

by Sandra Porter

If you've seen our blog posts about different forms of DNA (A, B, Z), nucleosomes, telomeres, or DNA sequencing, you might get the idea that we're a bit obsessed with DNA. And, you'd be right. We find DNA to be amazingly fascinating and beautiful, as well.

That fascination and sense of wonder inspired us to devote our first classroom digital biology lab ... Read more

by Todd Smith

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 ... Read more

 

by Todd Smith

Linear chromosomes are hard to maintain.

Replication fork - http://en.wikipedia.org/wiki/Telomere.

 

Every time their DNA gets replicated, it gets shorter. This is due to the fact that DNA polymerase can only add bases to the terminal 3'-OH of ... Read more