PSI. Pounds per square inch: a unit for measuring pressure. One PSI equals the pressure resulting from a force of one pound force acting over an area of one square inch. See pound.
  The four bases that make up RNA are:   * Adenine (A)  * Cytosine (C)  * Guanine (G)  * Uracil (U).denine and guanine are complementary, as are thymine and cytosine. RNA is practically the same, â¦ except that thymine is replaced with uracil (U) - meaning that when RNA replicates DNA, any thymine needed is replaced with uracil. Uracil is still compatible with cytosine, though.
DNA and RNA molecules are polymers (like polysaccharides and proteins). The building blocks (monomers) of nucleic acids are nucleotides. Each nucleotide is made up of a five-câ¦arbon sugar, a phosphate group, and a nitrogenous base. In terms of elements, they are made up of P, O, N, C, and H. In a recent find, though, a bacterial strain was using As instead of P.