Fifty years of making downwind sailing products means that we know what you need to sail off the wind, and we have a selection of poles and related fittings to do the job right for your boat. I can't imagine sailing downwind without my whisker pole. I make offshore passages for a living and I count on my Forespar* whisker pole.
Internal and external hydrogen bonds stabilize the DNA molecule. The two strands of DNA stay together by H bonds that occur between complementary nucleotide base pairs. Two hydrogen bonds occur between the adenosine and the thymine base pairs, and between the cytosine and the guanine there are three.
Each strand of the double helix is held together by covalent bonds between deoxyribose sugar and phosphate groups (on the 3' and 5' carbons) (making up the backbone). The bases-purines or pyrimidines - (adenine, guanine, cytosine and thymine) are also bonded onto the deoxyribose sugar (on 1' carbon) covalently.he DNA double helix is held together by hydrogen bonds and the nucleotide bases Adenine, Guanine, Cytosine, or Thymine. Check out the source I provided. There's a great diagram of the double helix. Source(s): http://www.ba-education.demon.co.uk/for/...