Genes are DNA nucleotides that encode genetic information. These nucleotides are the template by which DNA is transcribed to RNA.
DNA Composition and Structure
DNA, or deoxyribonucleic acid, is composed of nucleotides. A nucleotide is composed of a 5-carbon sugar, a phosphate group, and a nitrogenous base. All of the nucleotides of a eukaryotic cell are identical, with the exception of their respective nitrogenous bases. DNA is a double helix structure composed of two strands of nitrogenous bases. DNA is has four nitrogenous bases.
Each of the four nitrogenous bases bonds to its complement on the opposite strand. The resulting pairing of nitrogenous bases to its complement is called a base pair. Base pairs are bonded to each other with hydrogen bonds. Adenine and guanine have two rings and are called purines. Cytosine and thymine have only one ring and are referred to as pyrimidines. In DNA, one purine bonds with one pyrimidine. Adenine bonds with thymine using two hydrogen bonds, while cytosine bonds with guanine using three hydrogen bonds.
DNA is regenerated in a process called replication. Replication begins in the middle of DNA, where two replisomes govern replication by moving along a chromosome towards the end. One replisome produces a leading strand and the other produces a lagging strand.