What’s DNA? | Reside Science



DNA stands for deoxyribonucleic acid, which is a molecule that comprises the directions an organism must develop, reside and reproduce. These directions are discovered inside each cell and are handed down from dad and mom to their offspring.

What’s DNA product of?

DNA is made up of molecules referred to as nucleotides. Every nucleotide comprises a phosphate group, a sugar group and a nitrogen base. The 4 varieties of nitrogen bases are adenine (A), thymine (T), guanine (G) and cytosine (C). 

Nucleotides are connected collectively to kind two lengthy strands that spiral to create a construction referred to as a double helix. When you consider the double-helix construction as a ladder, the phosphate and sugar molecules can be the edges, whereas the bottom pairs can be the rungs. The bases on one strand pair with the bases on one other strand: Adenine pairs with thymine (A-T), and guanine pairs with cytosine (G-C).

Human DNA is made up of round 3 billion base pairs, and greater than 99% of these bases are the identical in all individuals, in accordance with the U.S. Nationwide Library of Medication (NLM).

Just like the way in which the order of letters within the alphabet can be utilized to kind phrases, the order of nitrogen bases in a DNA sequence varieties genes, which, within the language of the cell, inform cells the right way to make proteins. The shorthand for this course of is that genes “encode” proteins. However DNA shouldn’t be the direct template for protein manufacturing. To make a protein, the cell makes a replica of the gene, utilizing not DNA however ribonucleic acid, or RNA. This RNA copy, referred to as messenger RNA, tells the cell’s protein-making equipment which amino acids to string collectively right into a protein, in accordance with “Biochemistry” (W. H. Freeman and Firm, 2002).

DNA molecules are lengthy — so lengthy, in actual fact, that they cannot match into cells with out the appropriate packaging. To suit inside cells, DNA is coiled tightly to kind buildings referred to as chromosomes. Every chromosome comprises a single DNA molecule. People have 23 pairs of chromosomes, that are discovered inside every cell’s nucleus. 

Who found DNA?

(Picture credit score: Common Historical past Archive/Common Photographs Group by way of Getty Photographs)

DNA was first noticed by Swiss biochemist Friedrich Miescher in 1869, in accordance with a paper revealed in 2005 within the journal Developmental Biology. Miescher used biochemical strategies to isolate DNA — which he referred to as nuclein — from white blood cells and sperm, and decided that it was very completely different from protein. (The time period “nucleic acid” derives from “nuclein.”) However for a few years, researchers didn’t notice the significance of this molecule. 

In 1952, chemist Rosalind Franklin, who was working within the lab of biophysicist Maurice Wilkins, used X-ray diffraction — a manner of figuring out the construction of a molecule by the way in which X-rays bounce off it — to be taught that DNA had a helical construction. Franklin documented this construction in what grew to become referred to as Picture 51

In 1953, Wilkins confirmed the picture to biologists James Watson and Francis Crick — with out Franklin’s information. Armed with the data that DNA was a double helix and former experiences that the bases adenine and thymine occurred in equal quantities inside DNA, as did guanine and cytosine, Watson and Crick revealed a landmark 1953 paper within the journal Nature. In that paper, they proposed a mannequin of DNA as we now comprehend it: a double helical ladder with sugar-phosphate sides and rungs made up of A-T and G-C base pairs. Additionally they urged that, primarily based on their proposed construction, DNA may very well be copied — and, due to this fact, handed on. 

Watson, Crick and Wilkins had been awarded the Nobel Prize in drugs in 1962 “for his or her discoveries in regards to the molecular construction of nucleic acids and its significance for info switch in residing materials.” Franklin was not included within the award, although her work was integral to the analysis. 

How does DNA operate?

Genes encode proteins that carry out all kinds of features for people (and different residing beings). The human gene HBA1, for instance, comprises directions for constructing the protein alpha globin, which is a part of hemoglobin, the oxygen-carrying protein in pink blood cells, in accordance with the NLM. To take one other instance, the gene OR6A2 encodes an olfactory receptor, a protein that detects odors within the nostril, scientists reported in 2021 in the journal Gene. Relying on which model of OR6A2 you have got, it’s possible you’ll love cilantro or suppose it tastes like cleaning soap, in accordance with a examine revealed in 2012 within the journal Flavour

How is DNA sequenced?

DNA sequencing entails expertise that enables researchers to find out the order of bases in a DNA sequence. The expertise can be utilized to find out the order of bases in genes, chromosomes or a complete genome. In 2000, researchers accomplished a “working draft” sequence of the human genome, in accordance with the Nationwide Human Genome Analysis Institute, and completed the undertaking in 2003.

(Picture credit score: BSIP/UIG by way of Getty Photographs)

DNA testing

An individual’s DNA comprises details about their heritage, and it will probably typically reveal whether or not they’re at an elevated threat for sure illnesses. DNA exams, or genetic exams, are used for quite a lot of causes, together with to diagnose genetic problems, to find out whether or not an individual is a provider of a genetic mutation that they may go on to their youngsters and to look at whether or not an individual is in danger for a genetic illness. For example, sure mutations within the BRCA1 and BRCA2 genes are identified to extend the danger of breast and ovarian cancers, and evaluation of those genes in a genetic check can reveal whether or not an individual has these mutations.

Genetic check outcomes can have implications for an individual’s well being, and the exams are sometimes supplied together with genetic counseling to assist people perceive the outcomes and penalties.

Folks additionally use the outcomes of genetic testing to search out family and find out about their household bushes by firms comparable to Ancestry and MyHeritage. 

Further reporting by Alina Bradford and Ashley P. Taylor, Reside Science contributors.

Further sources



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