DNA, which stands for deoxyribonucleic acid, is a molecule that supplies the genetic instructions that tell living creatures how to develop, live and reproduce. DNA can be found inside every cell and is passed down from parents to their offspring.
What is actually DNA made from?
DNA is made up of molecules called nucleotides. Each nucleotide contains three components: a phosphate group, which is one phosphorus atom bonded to four oxygen atoms; a sugar molecule; and a nitrogen base. The four types of nitrogen bases are adenine (A), thymine (T), guanine (G) and cytosine (C), and together, these serve as the “letters” that make up the genetic code of our DNA.
Nucleotides try attached along with her in order to create two enough time strands you to definitely spiral to manufacture a design titled a double helix. If you believe of one’s double-helix design just like the a ladder, the brand new phosphate and you will sugar particles is the corners, once the legs pairs could be the rungs. The fresh new bases on one strand couples into the basics for the several other strand: Adenine sets with thymine (A-T), and you may guanine sets having cytosine (G-C).
Human DNA is made up of around 3 billion base pairs, and more than 99% of those bases are the same in all people, according to the U.S. National Collection of Treatments (NLM).
Similar to the way that letters in the alphabet can be arranged to form words, the order of nitrogen bases in a DNA sequence forms genes, which, in the language of the cell, tell cells how to make healthy protein. The shorthand for this process is that genes “encode” proteins.
But DNA is not the direct template for protein production. To make a protein, the cell makes a copy of the gene, using not DNA but ribonucleic acid, or RNA. RNA shares a similar structure to DNA, except it contains only one strand, rather than two – so it looks like just one half of a ladder. In addition, while RNA has three of the four nitrogen bases in common with DNA, it uses a base called uracil rather than thymine to pair with adenine.
As a cell prepares to build a new protein, its DNA unzips to expose one strand of the gene with the instructions to build said protein. Then, an enzyme zooms in and constructs a new RNA molecule whose sequence mirrors that of the unzipped gene. This RNA copy, called messenger RNA (mRNA), tells the cell’s protein-making machinery which proteins to string together into a protein, according to “Biochemistry” (W. H. Freeman and Company, 2002).
DNA molecules are long – so long, in fact, that they can’t fit into cells without the right packaging. To fit inside cells, DNA is coiled tightly to form structures called chromosomes. Each chromosome contains a single DNA molecule, wrapped tightly around spool-like proteins called histones, which provide chromosomes their structure. Humans have 23 pairs of chromosomes, which are found inside each cell’s nucleus, the control center of the cell.
Most chromosomes look like microscopic Xs; that said, humans and most other mammals carry a pair of sex chromosomes that can be either X or Y-shaped, with respect to the Federal Human Genome Look Institute. But there is some natural variation in the number of sex chromosomes people carry – sometimes, there may be extra sex chromosomes, or one might be missing, so other patterns, such as X, XXX, XXY and XXYY, can also occur, Pick stated.
Who discovered DNA?
DNA was first observed by Swiss 
biochemist Friedrich Miescher in 1869, according to a paper published in 2005 in the journal Developmental Biology. Miescher used biochemical methods to isolate DNA – which he then called nuclein – from white blood cells and sperm, and determined that it was very different from protein. (The term “nucleic acid” derives from “nuclein.”)