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).
The main features of the three-dimensional structure of DNA are: 1  DNA is double-stranded, so there are two polynucleotide stands alongside each other. 2  The two strands are wound round each other to form a double helix. 3  The two strands are joined together by hydrogen bonds between the bases. 4  The base pairs are specific. The base pairs are specific. 2  A only binds to T (and T with A), and C only binds to G (and G with C). 3  These are called complementary base pairs. 4  This means that whatever the sequence of bases along one strand, the sequence of bases on the other strand must be complementary to it.