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
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 a DNA chain. The DNA replication initiation complex uses RNA primers to provide the initial 3'-OH and to initiate "lagging" strand synthesis. While one strand can be copied all the way to the ... 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
The grocery store magazine covers all say that home made gifts are big this year. So I thought, some of you might like to channel your inner Martha Stewart and make gifts with a science theme.
Reposted in honor of the holiday and the economy.
I'm here to help to you make a merry mug with one of our favorite molecules. Yep, we're talking caffeine.
1. First, we'll go to ... Read more
Some people, like Imelda Marcos and Dr. Isis have a thing for fancy shoes. I go crazy for gadgets.
For my birthday this year, my family bought me a new iPhone! Yeah! So, I've been killing several hours today filling it with cute little iPhone apps. Who knew one little phone could be so much fun? One app, I enjoy, is called Molecules. Molecules lets you download structure files from the Protein Data Bank (PDB) and play with the structures on your phone!
Want to learn more about Parkinson's disease? See why a single nucleotide mutation messes up the function of a protein?
I have a short activity that uses Cn3D (a molecular viewing program from the NCBI) to look at a protein that seems to be involved in a rare form of Parkinson's disease and I could sure use beta testers.
If you'd like to do this, I need you to follow the directions below and afterwards, go to a web form and answer a few questions. Don't worry about getting the wrong answers. I won't know who ... Read more