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:10/13/2017)... ... October 13, 2017 , ... Global Healthcare Management’s 4th Annual ... in Milford, NJ. This free event, sponsored by Global Healthcare Management’s CEO, Jon ... fun run is geared towards children of all ages; it is a non-competitive, non-timed ...
(Date:10/13/2017)... ... October 13, 2017 , ... ... Agile Software Development, has been awarded a contract by the Center for Medicare ... (BPA) aims to accelerate the enterprise use of Agile methodologies in a consistent ...
(Date:10/12/2017)... ... October 12, 2017 , ... First ... compliance program management, will showcase a range of technology and learning solutions at ... (NCAL) Convention and Expo to be held October 14–18, 2017 at the Mandalay ...
(Date:10/12/2017)... , ... October 12, 2017 , ... ... to meet the demand of today’s consumer and regulatory authorities worldwide. From Children’s ... experts and tested to meet the highest standard. , These products are ...
(Date:10/12/2017)... ... October 12, 2017 , ... Asante, a nationally recognized ... have expanded their existing home health joint venture through an agreement, effective October ... a joint venture home health company with Asante, delivering clinically integrated care, for ...
Breaking Medicine News(10 mins):
(Date:10/2/2017)... Diplomat Pharmacy, Inc. (NYSE: DPLO ... LLC , and named its founder as Diplomat,s chief ... Tennessee , will operate under Diplomat subsidiary ... offerings for health care partners to include IT outsourcing, ... "In an interoperable world, technology delivers comprehensive insight ...
(Date:9/28/2017)... , Sept. 28, 2017 Hill-Rom Holdings, ... 2017 earnings conference call and webcast on Friday, November ... a.m. (EDT) and ending at approximately 8:30 a.m. (CDT) ... discussing the company,s 2017 financial performance and guidance for ... opportunities, initiatives to enhance operational performance, and long-range financial ...
(Date:9/25/2017)... , Sept. 25, 2017  EpiVax, Inc., ... vaccine design, and immune-engineering today announced the launch ... the development of personalized therapeutic cancer vaccines. EpiVax ... provided exclusive access to enabling technologies to the ... MBA will lead EpiVax Oncology as Chief Executive ...
Breaking Medicine Technology: