Nucleases are enzymes that break phosphodiester bonds between nucleotides in nucleic acids. They can interact with cellular components including unsaturated lipids, amino acid residues and nucleic acids. Samples may be any material containing proteins or nucleic acids. Oligonucleotide synthesis is the chemical synthesis of sequences of nucleic acids. Essentially, IMP is converted into the purine nucleotides required for nucleic acid synthesis. He proposed that these nucleotide cofactors represent "fossils of nucleic acid enzymes". Two types of nucleic acids are DNA and RNA. Total concentration of molecules in categories such as protein, lipid or nucleic acid. CrRNAs associate with Cas proteins to form ribonucleotide complexes that recognize foreign nucleic acids. Analyzing proteins proves to be more difficult than analyzing nucleic acid sequences. Carbohydrates, lipids, proteins, and nucleic acids are all macromolecules. It can also refer to biomolecular complexes of proteins with nucleic acids and other cofactors. Multiple methods of nucleic acid purification exist. Antimetabolites interfere with the synthesis of nucleic acids. It is considered a molecular precursor of nucleic acids.