Osphena Â® should not be used if you have unusual vaginal bleeding, have or have had certain types of cancers (including cancer of the breast or uterus), have or have had blood clots, have had a stroke or heart attack, have severe liver problems, are allergic to Osphena Â® or any of its ingredients, or think you may be pregnant.
DNA structure. DNA is made up of molecules called nucleotides. Each nucleotide contains a phosphate group, a sugar group and a nitrogen base. The four types of nitrogen bases are adenine (A), thymine (T), guanine (G) and cytosine (C).The order of these bases is what determines DNA's instructions, or genetic code.NA is made up of molecules called nucleotides. Each nucleotide contains a phosphate group, a sugar group and a nitrogen base. The four types of nitrogen bases are adenine (A), thymine (T), guanine (G) and cytosine (C).
1 DNA contains four basic building blocks or âbasesâ: adenine (A), cytosine (C), guanine (G) and thymine (T). 2  The order, or sequence, of these bases form the instructions in the genome. 3  DNA is a two-stranded molecule.  DNA has a unique âdouble helixâ shape, like a twisted ladder.