One researcher's DNA is another's unicorn.
One researcher's DNA DNA: see nucleic acid.
or deoxyribonucleic acid
One of two types of nucleic acid (the other is RNA); a complex organic compound found in all living cells and many viruses. It is the chemical substance of genes. is another's unicorn
It looks like a DNA molecule. It meanders like a DNA molecule. It even appears to twist like a DNA molecule. But that doesn't mean it is one, warn two chemists at the University of Utah The University of Utah (also The U or the U of U or the UU), located in Salt Lake City, is the flagship public research university in the state of Utah, and one of 10 institutions that make up the Utah System of Higher Education. in Salt Lake City.
In the Feb. 8 SCIENCE, Thomas P. Beebe Jr. and Carol R. Clemmer caution that researchers using scanning tunneling microscopes (STMs) to image biological molecules deposited onto a commonly used graphite substrate often mistake biological-looking features of the graphite surface for the biomolecules This page aims to list articles on Wikipedia that describe particular biomolecules or types of biomolecules.
This list is not necessarily complete or up to date - if you see an article that should be here but isn't (or one that shouldn't be here but is), please update the page they aim to study.
Since their introduction in the early 1980s, STMs and related "scanning probe" instruments have provided researchers with observational revelations and unprecedented manipulative powers, even at the atomic level. Scientific journals now teem teem 1
v. teemed, teem·ing, teems
1. To be full of things; abound or swarm: A drop of water teems with microorganisms.
2. with striking STM (Scanning Tunneling Microscope) A microscope that can image down to the atomic level. An STM uses a piezoelectric tube with a tiny sharp tip at the end that is moved within nanometers of the object being sampled. images. "Awash with enthusiasm, the first pretty picture [that seems to show a biomolecule biomolecule /bio·mol·e·cule/ (-mol´e-kul) a molecule produced by living cells, e.g., a protein, carbohydrate, lipid, or nucleic acid.
a molecule produced by living cells, e.g. ! gets published," says biophysicist and STM researcher Stuart Lindsay of Arizona State University Arizona State University, at Tempe; coeducational; opened 1886 as a normal school, became 1925 Tempe State Teachers College, renamed 1945 Arizona State College at Tempe. Its present name was adopted in 1958. in Tempe.
But pitfalls lurk for the unwary. Last August, several speakers at an STM conference in Baltimore remarked that features of a substrate called highly ordered pyrolytic py·rol·y·sis
Decomposition or transformation of a compound caused by heat.
pyro·lyt graphite (HOPG HOPG Highly Oriented Pyrolytic Graphite ) can muddle interpretations of biomolecular studies. "People have been talking about [this problem! for a while, but until now no one had actually addressed it in a paper," Clemmer says.
She and Beebe used their STM to examine hundreds of blank HOPG surfaces. They found numerous features resembling what they would expect to see if they had deposited DNA or other biomolecules onto the blanks. Beebe admits he has fallen prey to these ambiguities in the past.
Looking at HOPG under an STM is "like looking at a marble floor in a bathroom: You can see anything you want to in it," Lindsay notes.
On HOPG surfaces, the Utah scientists and others have observed linear, periodic features easily mistaken for a chain-like DNA or protein molecule. Sometimes these features "meander" over atomic steps on the substrate, giving the false impression that they are independent of the surface. Some even appear to have a left-handed twist remarkably similar to the helical pitch of many biomolecules.
Beebe acknowledges a "very small probability" that his team's observations resulted from unexpected DNA contamination on the supposedly naked graphite. However, he says, "I strongly feel that that's not the case."
Graphite's propensity for harboring long, twisting, polymer-like features that match textbook representations of molecules like DNA can create a dangerous decoy for scientists who hunt for such molecules. "There are many reports due to come out which we think could be vulnerable to these problems," Beebe says.
He and Clemmer urge biomolecular researchers to abandon graphite for substrates less likely to mimic biological molecules. Some STM users, they note, are turning to gold, often deposited onto a mica surface, as a preferred substrate for such studies.