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 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 are attached with her in order to create several much time strands one spiral to make a pattern titled a double helix. If you believe of your twice-helix build while the a ladder, the latest phosphate and you may sugar particles may be the corners, due to the fact base sets is the rungs. The brand new basics using one string couples to your bases to your other strand: Adenine sets which have thymine (A-T), and you will guanine pairs which have 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. Federal Collection regarding Medication (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 genetics, which, in the language of the cell, tell cells how to make proteins. 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 amino College dating free acids to string together into a protein, according to “Chemistry” (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 National Peoples Genome Browse 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, Get a hold of advertised.
Which receive 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.”)