But in other parts of the world, and particularly for international itineraries involving multiple airlines, paper tickets are more common and it's taken 13 years from the time the first electronic ticket was issued in 1994 to the eradication of paper ticket stock issued by IATA.
The two DNA strands are held together by interchain hydrogen bonds. H-bonds pair the bases in one chain to the complementary bases in the other chain. (A/T and G/C). slide 2 of 4. Hydrogen Bonds in DNA A number factors are responsible for the stability of the DNA double helix structure, among them hydrogen bonds. 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.
DNA Structure and Function. 1  Watson-Crick model of DNA; double helix. 2  The double in the double helix means that DNA is found in a double-stranded form - 2 single-stranded chains of DNA stuck to each other via hydrogen bonding of the base pairs.3  The 2 single-strands are anti-parallel to each other. The double in the double helix means that DNA is found in a double-stranded form - 2 single-stranded chains of DNA stuck to each other via hydrogen bonding of the base pairs. 2  The 2 single-strands are anti-parallel to each other. 3  Going from 5' to 3' of one strand means going from 3' to 5' of the other strand.