44 Facts About DNA

Two DNA strands are known as polynucleotides as they are composed of simpler monomeric units called nucleotides.

DNA is a long polymer made from repeating units called nucleotides, each of which is usually symbolized by a single letter: either.

The structure of DNA is dynamic along its length, being capable of coiling into tight loops and other shapes.

Backbone of the DNA strand is made from alternating phosphate and sugar groups.

The sugar in DNA is 2-deoxyribose, which is a pentose sugar.

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Therefore, any DNA strand normally has one end at which there is a phosphate group attached to the 5' carbon of a ribose and another end at which there is a free hydroxyl group attached to the 3' carbon of a ribose .

The asymmetric ends of DNA strands are said to have a directionality of five prime end, and three prime end, with the 5' end having a terminal phosphate group and the 3' end a terminal hydroxyl group.

Stability of the dsDNA form depends not only on the -content but on sequence and length .

DNA sequence is called a "sense" sequence if it is the same as that of a messenger RNA copy that is translated into protein.

DNA can be twisted like a rope in a process called DNA supercoiling.

In nature, most DNA has slight negative supercoiling that is introduced by enzymes called topoisomerases.

The conformation that DNA adopts depends on the hydration level, DNA sequence, the amount and direction of supercoiling, chemical modifications of the bases, the type and concentration of metal ions, and the presence of polyamines in solution.

In DNA, fraying occurs when non-complementary regions exist at the end of an otherwise complementary double-strand of DNA.

However, branched DNA can occur if a third strand of DNA is introduced and contains adjoining regions able to hybridize with the frayed regions of the pre-existing double-strand.

Phosphate groups of DNA give it similar acidic properties to phosphoric acid and it can be considered as a strong acid.

DNA can be damaged by many sorts of mutagens, which change the DNA sequence.

For example, UV light can damage DNA by producing thymine dimers, which are cross-links between pyrimidine bases.

DNA usually occurs as linear chromosomes in eukaryotes, and circular chromosomes in prokaryotes.

The information carried by DNA is held in the sequence of pieces of DNA called genes.

For example, in transcription, when a cell uses the information in a gene, the DNA sequence is copied into a complementary RNA sequence through the attraction between the DNA and the correct RNA nucleotides.

Genomic DNA is tightly and orderly packed in the process called DNA condensation, to fit the small available volumes of the cell.

In eukaryotes, DNA is located in the cell nucleus, with small amounts in mitochondria and chloroplasts.

In prokaryotes, the DNA is held within an irregularly shaped body in the cytoplasm called the nucleoid.

Gene is a sequence of DNA that contains genetic information and can influence the phenotype of an organism.

Cell-free fetal DNA is found in the blood of the mother, and can be sequenced to determine a great deal of information about the developing fetus.

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Under the name of environmental DNA eDNA has seen increased use in the natural sciences as a survey tool for ecology, monitoring the movements and presence of species in water, air, or on land, and assessing an area's biodiversity.

Neutrophil extracellular traps are networks of extracellular fibers, primarily composed of DNA, which allow neutrophils, a type of white blood cell, to kill extracellular pathogens while minimizing damage to the host cells.

Structural proteins that bind DNA are well-understood examples of non-specific DNA-protein interactions.

In eukaryotes, this structure involves DNA binding to a complex of small basic proteins called histones, while in prokaryotes multiple types of proteins are involved.

Nucleases that hydrolyse nucleotides from the ends of DNA strands are called exonucleases, while endonucleases cut within strands.

RNA-dependent DNA polymerases are a specialized class of polymerases that copy the sequence of an RNA strand into DNA.

DNA contains the genetic information that allows all forms of life to function, grow and reproduce.

Claims for older DNA have been made, most notably a report of the isolation of a viable bacterium from a salt crystal 250 million years old, but these claims are controversial.

DNA profiling was developed in 1984 by British geneticist Sir Alec Jeffreys, and first used in forensic science to convict Colin Pitchfork in the 1988 Enderby murders case.

The most obvious defense to DNA matches obtained forensically is to claim that cross-contamination of evidence has occurred.

DNA profiling is used successfully to positively identify victims of mass casualty incidents, bodies or body parts in serious accidents, and individual victims in mass war graves, via matching to family members.

DNA profiling is used in DNA paternity testing to determine if someone is the biological parent or grandparent of a child with the probability of parentage is typically 99.

DNA is thus used as a structural material rather than as a carrier of biological information.

Nanomechanical devices and algorithmic self-assembly have been demonstrated, and these DNA structures have been used to template the arrangement of other molecules such as gold nanoparticles and streptavidin proteins.

DNA collects mutations over time, which are then inherited, it contains historical information, and, by comparing DNA sequences, geneticists can infer the evolutionary history of organisms, their phylogeny.

DNA was first isolated by the Swiss physician Friedrich Miescher who, in 1869, discovered a microscopic substance in the pus of discarded surgical bandages.

Levene suggested that DNA consisted of a string of four nucleotide units linked together through the phosphate groups .

In 1933, while studying virgin sea urchin eggs, Jean Brachet suggested that DNA is found in the cell nucleus and that RNA is present exclusively in the cytoplasm.

Franklin's identification of the space group for DNA crystals revealed to Crick that the two DNA strands were antiparallel.