* DNA and RNA Structure: DNA and RNA, the molecules that carry genetic information, are made up of nucleotides. Each nucleotide has three parts: a sugar molecule, a phosphate group, and a nitrogenous base.
* The Four Bases: There are four main nitrogenous bases: adenine (A), guanine (G), cytosine (C), and thymine (T) in DNA. In RNA, thymine is replaced with uracil (U).
* Sequence is Key: The sequence of these bases along a DNA or RNA strand is what determines the genetic code. This sequence acts like a blueprint, dictating the order of amino acids in proteins.
* Codons: Three-base sequences (called codons) within DNA and RNA code for specific amino acids. The order of codons determines the order of amino acids, which in turn determines the structure and function of a protein.
In essence, the nitrogenous bases act as the "letters" of the genetic code, and their specific sequence carries the instructions for building and maintaining an organism.
