What is DNA?
DNA is the molecule that is the hereditary material in all living cells.
Genes are made of DNA, and so is the genome itself. A gene consists of enough DNA to code for one protein, and a genome is simply the sum total of an organism's DNA.
DNA is long and skinny, capable of contorting like a circus performer when it winds into chromosomes. It's skinny as a whip and smart as one too, containing all the information necessary to build a living organism. In a very real sense, DNA is information.
What is DNA made of?
DNA is a very large molecule, made up of smaller units called nucleotides that are strung together in a row, making a DNA molecule thousands of times longer than it is wide.
Each nucleotide has three parts: a sugar molecule, a phosphate molecule, and a structure called a nitrogenous base. The nitrogenous base is the part of the nucleotide that carries genetic information, so the words "nucleotide" and "base" are often used interchangeably. The bases found in DNA come in four varieties: adenine, cytosine, guanine, and thymine—often abbreviated as A, C, G, and T, the letters of the genetic alphabet.
Genetics is the study of genes—what they are, what they do, and how they work. Genes inside the nucleus of a cell are strung together in such a way that the sequence carries information: that information determines how living organisms inherit various features (phenotypic traits). For example, offspring produced by sexual reproduction usually look similar to each of their parents because they have inherited some of each of their parents' genes. Genetics identifies which features are inherited, and explains how these features pass from generation to generation. In addition to inheritance, genetics studies how genes are turned on and off to control what substances are made in a cell—gene expression; and how a cell divides—mitosis or meiosis.
A genome is an organism's complete set of genetic instructions. Each genome contains all of the information needed to build that organism and allow it to grow and develop. ... The instructions in our genome are made up of DNA. Within DNA is a unique chemical code that guides our growth, development and health.