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 the natural world. One example is DNA ... Read more
What’s the first you think about when you see a spider? Running away? Danger? Fairies? Spiderman?
Do you wonder if spider silk is really strong enough to stop a train, like they showed in Spiderman 2?
Whatever your thoughts, you’re probably not thinking about 3D printing in space ... Read more
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
Today (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.
As we are taught in school, the double stranded DNA molecule is a right-handed helix as determined by Watson and Crick using Franklin's x-ray diffraction images . This B- ... Read more