What is the basic structure of a gene?

A gene is the basic unit of inheritance. It is located on a specific region on the chromosome known as the locus.  

A gene is composed of a double helix DNA. The two DNA strands run in antiparallel directions and wind about each other in a manner that resembles a twisted ladder. 

The DNA strands consist of nucleotide monomers, which are made up of a phosphate group, a pentose sugar (deoxyribose) and one of four nitrogenous bases - Adenine (A), Thymine (T), Cytosine (C), or Guanine (G). The sugars and phosphates make up the sides of the ladder, while bonded pairs of nitrogenous bases form the rungs of the ladder. 

Two types of elements go into making up the gene structure - core elements and regulatory elements. The core elements, which include introns and exons, actively participate in protein synthesis. The regulatory elements, which include promoters, enhancers, and silencers play roles in maintaining gene expression.