a

One of the four nucleotides used in building DNA; all four nucleotides have a common phosphate group and a sugar (ribose).

The blood group whose red cells carry the A antigen.

Any of several fat-soluble vitamins essential for normal vision; prevents night blindness or inflammation or dryness of the eyes.

The basic unit of electric current adopted under the Systeme International d'Unites.

“a typical household circuit carries 15 to 50 amps”

A metric unit of length equal to one ten billionth of a meter (or 0.0001 micron); used to specify wavelengths of electromagnetic radiation.

(biochemistry) purine base found in DNA and RNA; pairs with thymine in DNA and with uracil in RNA.

The 1st letter of the Roman alphabet.