Navigation Links
This is Why DNA Has Its Famous Helix Shape

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 .

The study conducted by Piotr Marszalek, a professor of mechanical engineering at Duke said that the first direct measurements of the forces within single strands of DNA that wind around each other in pairs to form the complete, double-stranded molecules.

"The stability of DNA is so fundamental to life that it's important to understand all factor. If you want to create accurate models of DNA to study its interaction with proteins or drugs, for example, you need to understand the basic physics of the molecule. For that, you need solid measurements of the forces that stabilize DNA," Marszalek said.

Each DNA strand includes a sugar and phosphate "backbone" attached to one of four bases, which encode genetic sequences. The strength of the interactions within individual strands comes largely from the chemical attraction between the stacked bases. But the integrity of double-stranded DNA depends on both the stacking forces between base units along the length of the double helix and on the pairing forces between complementary bases, which form the rungs of the twisted ladder.

According to Marszalek, earlier studies have focused more attention on the chemical bonds between opposing bases, measuring their strength by "unzipping" the molecules' two strands,. Studies of intact DNA make it difficult for researchers to separate the stacking from the pairing forces.

"To get around that problem in the new study, the Duke team used an atomic force microscope (AFM) to capture the "mechanical fingerprint" of the attraction between bases within DNA strands. The bonds within the molecules' sugar and phosphate backbones remained intact and therefore had only a minor influence on the force measurements," Marszalek said.

They tugged on individual strands that were tethered at one end to gold and measured the changes in force as they pulled. The AFM technique allows precise measurements of forces within individual molecules down to one pico-Newton--a trillionth of a Newton. For a sense of scale, the force of gravity on a two-liter bottle of soda is about 20 Newtons.

"They captured the range of stacking forces by measuring two types of synthetic DNA strands: some made up only of the base thymine, which is known to have the weakest attraction between stacked units, and some made up only of the base adenine, known to have the strongest stacking forces. Because of those differences in chemical forces, the two types of single-stranded DNA take on different structures," Marszalek said.

Single strands of adenine coil in a fairly regular fashion to form a helix of their own, while thymine chains take on a more random shape.

The pure adenine strands exhibited an even more complex form of elasticity than had been anticipated, the researchers reported. As they stretched the adenine chains with increasing force, the researchers noted two places-at 23 and 113 pico-Newtons--where their measurements levelled off.

"Those plateaus reflect the breaking and unfolding of the helix. With no bonds between bases to break, the thymine chains' showed little resistance to extension and no plateau," Marszalek explained.

"Based on the known structure of the single stranded DNA molecules, they had expected to see only one such plateau as the stacking forces severed. Exactly what happens at the molecular level at each of the two plateaus will be the subject of continued investigation," he said.

The study is published online by Physical Review Letters on July 5.


'"/>




Related medicine news :

1. Breast Cancer’s Does Not Discriminate – Rich and Famous Who have had Breast Cancer and Survivd
2. Famous Faces Join Campaign To Spread Awareness On Ovarian Cancer
3. More Than a Million Expected for Spains Famous Bull Run Festival
4. Shapely sperm-a valuable indicator of fertility
5. Genetics Has A Major Role To Play In Body Shape.
6. World Heart Day To Focus On Ideal Body Weight And Shape To Reduce Risk Of Heart Disease
7. Mental Health Services In Poor Shape
8. Americans Growing Out Of Shape
9. Mental Health Services at Wellington Hospital in Poor Shape
10. Baby Boomers: Shape up or get shipped out!
11. Shapelier Knee Replacements for Women
Post Your Comments:
*Name:
*Comment:
*Email:


(Date:9/22/2017)... ... ... “Letters From Home”: a moving compilation of letters that remind readers of ... Home” is the creation of published author, John Allred, a passionate leader of ministry ... International, who has traveled and ministered on four continents. , “It is my hope ...
(Date:9/21/2017)... CA (PRWEB) , ... September 21, 2017 , ... With ... so fun and easy to do. Users can select from up to two layers ... with a click of a mouse all within Final Cut Pro X. ...
(Date:9/21/2017)... ... September 21, 2017 , ... The American Addiction Treatment ... for professionals in the addiction treatment industry entitled: Special Investigations Unit (SIU) ... companies and state and federal governments are increasingly scrutinizing the addiction treatment industry ...
(Date:9/21/2017)... ... ... Bill Howe Plumbing’s mission is to create an employee friendly company, provide ... over 37 years, they have operated with their mission at the foundation and have ... They were chosen as the Best San Diego plumber in 2016, named a Top ...
(Date:9/21/2017)... , ... September 21, 2017 , ... ... developing low-cost and highly accurate cancer screening tests, has received two prestigious recognitions ... in cancer survival rates. , Preora has been named a Top ...
Breaking Medicine News(10 mins):
(Date:9/12/2017)... , Sept. 12, 2017   EcoVadis , the leading platform for ... the first annual edition of its Global CSR Risk and Performance Index. ... by EcoVadis, based on Scorecard Ratings that analyzed nearly 800,000 data points ... ... ...
(Date:9/9/2017)... , Sept. 9, 2017  Eli Lilly and ... primary and secondary endpoint data for lasmiditan, an investigational, ... which demonstrated statistically significant improvements compared to placebo in ... highlighted today at the 18th Congress of the International ... "The data presented today demonstrate lasmiditan,s potential ...
(Date:9/7/2017)... WARSAW, Ind. , Sept. 7, 2017  Zimmer ... leader in musculoskeletal healthcare, today announced that it will ... Annual Global Healthcare Conference at the Grand Hyatt hotel ... September 11, 2017 at 11:40 a.m. Eastern Time. ... accessed via Zimmer Biomet,s Investor Relations website at ...
Breaking Medicine Technology: