Florence (Firenze) 10 day weather forecast, updated four times a day and shows the weather summary plus detailed sun, rain, snow, wind and temperature. The weather forecast extends out to 10 days showing information for morning, afternoon and overnight.
Definition of double helix. : a helix or spiral consisting of two strands in the surface of a cylinder that coil around its axis; especially : the structural arrangement of DNA in space that consists of paired polynucleotide strands stabilized by cross-links between purine and pyrimidine bases â compare alpha-helix, watson-crick model.
The double helix describes the appearance of double-stranded DNA, which is composed of two linear strands that run opposite to each other, or anti-parallel, and twist together.Each DNA strand within the double helix is a long, linear molecule made of smaller units called nucleotides that form a chain.he chemical backbones of the double helix are made up of sugar and phosphate molecules that are connected by chemical bonds, known as sugar-phosphate backbones.