DNA, or deoxyribonucleic acid, is the hereditary material in humans and almost all other organisms. Nearly every cell in a person’s toàn thân has the same DNA. Most DNA is located in the cell nucleus (where it is called nuclear DNA), but a small amount of DNA can also be found in the mitochondria (where it is called mitochondrial DNA or mtDNA). Mitochondria
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The information in DNA is stored as a code made up of four chemical bases: adenine (A), guanine (G), cytosine (C), & thymine (T). Human DNA consists of about 3 billion bases, và more than 99 percent of those bases are the same in all people. The order, or sequence, of these bases determines the information available for building & maintaining an organism, similar to lớn the way in which letters of the alphabet appear in a certain order to lớn khung words và sentences.
DNA bases pair up with each other, A with T and C with G, to size units called base pairs. Each base is also attached khổng lồ a sugar molecule and a phosphate molecule. Together, a base, sugar, and phosphate are called a nucleotide. Nucleotides are arranged in two long strands that khung a spiral called a double helix. The structure of the double helix is somewhat like a ladder, with the base pairs forming the ladder’s rungs & the sugar and phosphate molecules forming the vertical sidepieces of the ladder.
An important property of DNA is that it can replicate, or make copies of itself. Each strand of DNA in the double helix can serve as a pattern for duplicating the sequence of bases. This is critical when cells divide because each new cell needs khổng lồ have an exact copy of the DNA present in the old cell.
DNA is a double helix formed by base pairs attached khổng lồ a sugar-phosphate backbone.
Credit: U.S. National Library of Medicine
For more information about DNA:
The National Human Genome Retìm kiếm Institute (NHGRI), a part of the National Institutes of Health (NIH), provides a fact sheet Deoxyribonucleic Acid (DNA) that gives an introduction lớn this molecule.
StatedClearly offers a đoạn Clip introduction khổng lồ DNA & how it works.
The New Genetics, a publication of the National Institute of General Medical Sciences, part of the NIH, discusses the structure of DNA & how it was discovered.
A basic explanation và illustration of DNA can be found on Arizomãng cầu State University"s "Ask a Biologist" trang web.
The Virtual Genetics Education Centre, created by the University of Leicester, offers additional information on DNA, genes, và chromosomes.
An overview of mitochondrial DNA is available from the Neuromuscular Disease Center at Washington University in St. Louis.
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The resources on this site should not be used as a substitute for professional medical care or advice. Users with questions about a personal health condition should consult with a qualified healthcare professional.
U.S. National Library of Medicine 8600 Rockville Pike, Bethesda, MD 20894 U.S. Department of Health & Human Services National Institutes of Health