double helix of 2 comp polyNT strands >

2 strands coil around EO, form right-handed double helix >

2 strands antiparallel, 1 runs 5'>3', comp strand 3'>5' >

each strand consists long chain of DNA NT >

DNA NT comprises doxyribose sugar, phosphate group & 1/4 nitrogenous bases(ATCG) >

each strand contains SP backbone maintained by PDE bonds b/w -OH group on C₃ of 1 NT, P group on C₅ of adjacent NT >

bases arranged as side groups of strands, width b/w 2 SP backbones = 2nm = 1bp >

1 complete turn of double helix = 3.4nm(10bp) >

surface of molecule has major, minor grooves >

bases of 1 strand pairs w/ opposite strand bases by H bonding >

AT 2H bonds, CG 3H bonds >

base pairing specific & complementary, A>T, C>G >

molecule stabilised by hydrophobic interactions b/w stacked bases

Review: H2 Biology 7 - DNA Replication(i)