Nucleic acids

both deoxyribonucleic acid (dna) and ribonucleic acid (rna) are polymers of nucleotides. NUCLEOTIDES HAVE THREE ESSENTIAL PARTS:

§       (1) a sugar -- either ribose or deoxyribose;

§       (2) a base -- either a purine such as guanine (g) or adenine (a) or a pyrimidine such as thymine (t), cytosine (c) or uracil (u);

§       (3) a phosphate group.

Nucleotides can be covalently linked into a single strand of nucleic acid by forming covalent bonds between the phosphate groups and the 3' oh group of the sugars of a series of nucleotides.

A single stranded piece of nucleic acid can base-pair or hybridize with a complementary piece of nucleic acid by forming non-covalent hydrogen bonds between complementary bases.

The biochemically complementary bases are:

·      a-t

·      a-u

·      g-c.

Double stranded nucleic acids can be melted into single strands in the laboratory by raising the temperature and they will hybridize again when the temperature is lowered.

Within the cell, melting and reannealing is done by enzymes.

 note that atp is a nucleotide as is camp.