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DNA

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Genetics. deoxyribonucleic acid: an extremely long macromolecule that is the main component of chromosomes and is the material that transfers genetic characteristics in all life forms, constructed of two nucleotide strands coiled around each other in a ladderlike arrangement with the sidepieces composed of alternating phosphate and deoxyribose units and the rungs composed of the purine and pyrimidine bases adenine, guanine, cytosine, and thymine: the genetic information of DNA is encoded in the sequence of the bases and is transcribed as the strands unwind and replicate.Compare base pair, gene, genetic code, RNA.
the set of nongenetic traits, qualities, or features that characterize a person or thing: Humility is just not in her DNA.

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Origin of DNA

1930–35; d(eoxyribo)n(ucleic)a(cid)
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2021

HOMEWORK HELP

What is DNA?

DNA is a large, complex molecule that allows cells to function and carries the genetic code that determines the traits of a living organism.

DNA is in every cell of every living thing. Some viruses also have DNA.

Life as we know it wouldn’t exist without DNA—it contains the instructions that cells need to function. DNA is found in the cell nucleus, and every cell in an organism has the exact same copy of DNA that is in every other cell. Each cell uses its copy of DNA whenever it needs to make a protein. Proteins have many essential jobs within a living thing. For example, your immune system produces proteins called antibodies to fight germs.

The information that’s in DNA controls the development of specific traits, such as the shape of a leaf or the color of hair. Specifically, such traits are determined by genes, which are segments of DNA within strands called chromosomes. The set of all information contained in the DNA of any living thing—all of its inheritable traits—is called its genome.

DNA is an abbreviation of deoxyribonucleic acid. It is a type of macromolecule (a very large molecule—one composed of hundreds of thousands of atoms) known as a nucleic acid. Nucleic acids are made of smaller molecules known as nucleotides, which are made of a phosphate, a sugar, and nitrogen bases. The four nitrogen bases in DNA are adenine (A), thymine (T), guanine (G), and cytosine (C).

DNA has a shape known as a double helix, which resembles a spiraled ladder. The DNA ladder is built from two very long strands of nucleotides with the nitrogen bases pairing together to form the rungs of the ladder. The bases form base pairs, with adenine always paired to thymine and guanine always paired to cytosine. The phosphate and sugar within the nucleotide act as the sides of the ladder.

Because DNA only exists within the cell’s nucleus, the genetic information must be distributed somehow. This is one of the roles of RNA, which is a macromolecule that works alongside DNA to make proteins. During this process, RNA acts as a kind of copy of the DNA that carries its genetic information outside of the cell nucleus.

We took a microscopic look at the differences between DNA, RNA, and mRNA, and their vital roles. Read all about it here!

Why is DNA important?

DNA is ancient, but its discovery was relatively recent. In 1869, chemist Friedrich Miescher documented a kind of molecule that had never been studied before—nucleic acid. It wasn’t until around the 1930s that the term DNA began to be used. In the 1950s, the work of biophysicist Rosalind Franklin and biologists James Watson and Francis Crick revealed DNA’s double helix structure.

Cells cannot make proteins without DNA. DNA acts as a set of instructions for any protein that needs to be made.

The study of DNA is central to the field of science known as genetics. DNA contains genetic information that is passed down from one generation to another. You get roughly half of your DNA from your mother and half from your father. This is the reason children look similar but not identical to their parents.

Despite the vast range of different physical traits that people can have, the DNA of all humans is more than 99% identical. Human DNA is made of billions of nitrogen bases, and even minor differences can result in two people that look very different. (Identical twins are born with the exact same DNA.)

The order of nitrogen base pairs is what makes every person and every living thing unique. For example, minor differences in this sequence determine whether a person will have brown eyes or blue eyes.

Did you know ... ?

DNA is analyzed in the study of human evolution. Our closest living biological relatives are chimpanzees and bonobos, whose DNA is over 98% identical to ours. This fact has contributed to the theory that humans and chimpanzees share a common ancestor that lived millions of years ago.

What are real-life examples of DNA?

This illustration shows a simplified rendition of DNA’s double helix structure.

Getty. DNA double helix.

DNA is crucial to life, and learning about DNA is a crucial part of the study of biology.

 

Quiz yourself!

True or False?

DNA is essential to life because it contains instructions for the production of proteins.

How to use DNA in a sentence

British Dictionary definitions for DNA

DNA

noun

deoxyribonucleic acid; a nucleic acid that is the main constituent of the chromosomes of all organisms (except some viruses). The DNA molecule consists of two polynucleotide chains in the form of a double helix, containing phosphate and the sugar deoxyribose and linked by hydrogen bonds between the complementary bases adenine and thymine or cytosine and guanine. DNA is self-replicating, plays a central role in protein synthesis, and is responsible for the transmission of hereditary characteristics from parents to offspringSee also genetic code

abbreviation for

did not attend
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Medical definitions for DNA

DNA
[ dē′ĕn-ā ]

n.

Deoxyribonucleic acid; a nucleic acid that consists of two long chains of nucleotides twisted together into a double helix and joined by hydrogen bonds between complementary bases adenine and thymine or cytosine and guanine; it carries the cell's genetic information and hereditary characteristics via its nucleotides and their sequence and is capable of self-replication and RNA synthesis.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

Scientific definitions for DNA

DNA
[ dē′ĕn-ā ]

Short for deoxyribonucleic acid. The nucleic acid that is the genetic material determining the makeup of all living cells and many viruses. It consists of two long strands of nucleotides linked together in a structure resembling a ladder twisted into a spiral. In eukaryotic cells, the DNA is contained in the nucleus (where it is bound to proteins known as histones) and in mitochondria and chloroplasts. In the presence of the enzyme DNA polymerase and appropriate nucleotides, DNA can replicate itself. DNA also serves as a template for the synthesis of RNA in the presence of RNA polymerase. Compare RNA. See Note at histone.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

Cultural definitions for DNA

DNA

The molecule that carries genetic information in all living systems (see genetic code). The DNA molecule is formed in the shape of a double helix from a great number of smaller molecules (see nucleotides). The workings of the DNA molecule provide the most fundamental explanation of the laws of genetics.

DNA acts in three important way. First, when a cell divides, the DNA uncoils, and each strand creates a new partner from the surrounding material — a process called replication. The two cells that result from the cell division have the same DNA as the original (see mitosis). Second, in sexual reproduction, each parent contributes one of the two strands in the DNA of the offspring. Third, inside the cell, the DNA governs the production of proteins and other molecules essential to cell function.

The New Dictionary of Cultural Literacy, Third Edition Copyright © 2005 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
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