Adenine, thymine, guanine, and cytosine are make up the nucleotides of dna

The four nitrogenous bases

Helpful Tip:

To know which base goes with which

Remember

Car in the Garage

Cytosine and Guanine

and

Apple in the Tree

(Adenine and Thymine)

an active site is a region that is present on an enzyme where the reactants or the substrate molecules we can say bind and experience a chemical reaction. the substrate is basically a reactant whose concentration is changing and that is converting into a product after binding at the active site of an enzyme