DNA falls apart when you pull it

May 20, 2011
Artist's impression of optical tweezers used to pull DNA. On both ends of the DNA, beads are glued that are held by a laser beam. With the laser beam, the DNA can be pulled, by which, as can be seen on the left, it falls apart.

DNA falls apart when you pull it with a tiny force: the two strands that constitute a DNA molecule disconnect. Peter Gross of VU University Amsterdam has shown this in his PhD research project. With this research, researchers can now have a better understanding of how DNA in cells is locally opened so genes can be turned ‘on’ or ‘off’.

DNA is one of the most important molecules in cells because it contains the . A consists of two strands that are wound around each other and connected together like a spiral staircase: the double helix. Whether the genetic code in a piece of DNA is actually used, partially depends on the ease with which the two DNA strands separate from each other – like a zipper. Because that is required in order to read the genetic code. When you heat DNA in a test tube to about 80 degrees Celsius, the two strands fall apart, they ‘melt’. use a different way to melt DNA: proteins pull the DNA strands apart.

To investigate this process of pulling DNA, Peter Gross used so-called optical tweezers to pull the DNA with tiny forces. Simultaneously, he used fluorescence microscopy to see closely what happens to the DNA. What he saw can be described as a game of tug of war with a frayed rope: when you pull harder, the rope frays further and further apart. When Peter Gross increased the force on the DNA, he saw that the DNA strands fall apart with tiny shocks. He could accurately analyze these shocks and saw that the pattern of shocks is determined by the genetic code of the DNA: the pattern is like a fingerprint of the DNA. He also observed that the two DNA strands spontaneously join together and form a double helix again when he reduced the force on the DNA. This research has led to a better understanding of the complex properties of , in particular the stability of the .

Explore further: Nanoscopic gold spheres can be reversibly bound to DNA strands reversibly bound to DNA strands

Related Stories

DNA constraints control structure of attached macromolecules

June 28, 2005

A new method for manipulating macromolecules has been developed by researchers at the University of Illinois at Urbana-Champaign. The technique uses double-stranded DNA to direct the behavior of other molecules. In previous ...

Stretching DNA to the Limit: DNA damage in a new light

April 20, 2007

It has long been known that UV light can damage DNA, reducing its ability to replicate and interact with proteins, and often resulting in the development of skin cancers. However, not much is known about how the elasticity ...

Unraveling the physics of DNA's double helix

July 12, 2007

Researchers at Duke University's Pratt School of Engineering have uncovered a missing link in scientists' understanding of the physical forces that give DNA its famous double helix shape.

Recommended for you

Findings illuminate animal evolution in protein function

July 27, 2015

Virginia Commonwealth University and University of Richmond researchers recently teamed up to explore the inner workings of cells and shed light on the 400–600 million years of evolution between humans and early animals ...

New polymer able to store energy at higher temperatures

July 30, 2015

(Phys.org)—A team of researchers at the Pennsylvania State University has created a new polymer that is able to store energy at higher temperatures than conventional polymers without breaking down. In their paper published ...

How to look for a few good catalysts

July 30, 2015

Two key physical phenomena take place at the surfaces of materials: catalysis and wetting. A catalyst enhances the rate of chemical reactions; wetting refers to how liquids spread across a surface.

Yarn from slaughterhouse waste

July 29, 2015

ETH researchers have developed a yarn from ordinary gelatine that has good qualities similar to those of merino wool fibers. Now they are working on making the yarn even more water resistant.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.