From Citizendium, the Citizens' Compendium
DNA (Deoxyribonucleic acid) provides the genetic information necessary for the development and reproduction of all living organisms and is often described as a genetic blueprint.[1] Every living organism has its own DNA code that is organized in the ladder-like structure of the DNA molecule as a series of complementary paired molecules called bases.
DNA functions as a template: information is transferred from the sequence of base pairs within the DNA, by a molecule called messenger RNA (mRNA), to an enzyme called a ribosome (a biochemical assembly machine). The ribosome translates the code by assembling a protein molecule from amino acids (the building blocks of proteins) according to the base pair sequence brought to it by the mRNA. Proteins are very complex molecules used for signaling, regulation, metabolism and structural components. Cells containing DNA in any one organism have the same DNA, but each different cell type will synthesize its own characteristic combination of proteins, some common to most cells, while others are more specialized and help to define the functions of that particular cell type.
It is the complementary structure of DNA which enables it to function as a template for translating the genetic code and the assembly of the proteins. This complementary structure also enables the double stranded DNA to be separated and replicated as two exact duplicates during cell division (replication). [2]
In most organisms, DNA is formed as a very long and very narrow double-helix formation of two DNA strands coiled around each other in a head-to-toe "antiparallel" orientation. The strands provide structural support for a complementary pair of bases located inbetween the strands (a base pair is like a letter of a genetic word). A sequence of three base pairs forms a codon ( a DNA word) on the DNA strand that encodes the information for one amino acid residue. A series of codons, and associated start/stop codons, (a DNA sentence or gene) forms the genetic code for the selection of particular amino acids and their specific arrangement necessary for the assembly of a particular protein molecule. The protein molecules, as many as 20,000 different types, are used in the cell, or are transported, often via small containers (vesicles), to other areas of the organism.
Each single strand of DNA is a long biopolymer comprised of repeating units called nucleotides. A nucleotide is a base linked to a sugar and phosphate group which form a sugar/phosphate backbone. Attached to each sugar molecule (deoxyribose) is one of the four bases:
The corresponding deoxynucleosides are:
Nuclear DNA is organized and stored as chromosomes within the nucleus. The nucleus is a double membrane separating the DNA from the cytoplasm of the cell enabling certain processing to occur prior to protein synthesis. Each chromosome holds hundreds or thousands of genes. A gene can be described in different ways but in general can be thought of as a whole unit of genetic information.
At conception, the male sperm, (a half stranded DNA with a protein coat), and female ovum, (an unfertilized egg also containing a single strand of DNA), each contribute 23 chromosomes for a total of 46 chromosomes in the fertilized embryo. The total sum of chromosomes is called the kayrotype in eukaryotes (organisms such as plants, yeasts and animals whose cells have a nucleus)
Some organelles in eukaryotic cells (mitochondria and chloroplasts) have their own DNA with a similar organization to bacterial genomes. This DNA encodes for some of the functions in these organelles. Both the mitochondrial DNA (mtDNA) and the chloroplast DNA (cpDNA) originate in the female egg, so the organelle DNA is always inherited from the mother. Some cells, such as blood cells, do not have a nucleus and do not contain DNA. In prokaryote cells (organisms such as common bacteria), DNA is located in a region called the nucleoid. Viruses have a single type of nucleic acid, either DNA or RNA, directly encased in a protein coat called the capsid.
Continued here:
DNA - encyclopedia article - Citizendium
- DNA database helps solve thousands of Texas crimes [Last Updated On: January 3rd, 2013] [Originally Added On: January 3rd, 2013]
- Revealed DNA - The Next Wave - Video [Last Updated On: January 3rd, 2013] [Originally Added On: January 3rd, 2013]
- DNA-Little Mix (Molly cover) - Video [Last Updated On: January 5th, 2013] [Originally Added On: January 5th, 2013]
- 'Junk DNA' made visible before the final cut [Last Updated On: January 7th, 2013] [Originally Added On: January 7th, 2013]
- 'Junk DNA' made visible before the final cut [Last Updated On: January 7th, 2013] [Originally Added On: January 7th, 2013]
- HUMAN DNA. A Speech To The Lord - Video [Last Updated On: January 19th, 2013] [Originally Added On: January 19th, 2013]
- 'Quadruple helix' DNA discovered in human cells [Last Updated On: January 21st, 2013] [Originally Added On: January 21st, 2013]
- 'Quadruple helix' DNA discovered in human cells [Last Updated On: January 21st, 2013] [Originally Added On: January 21st, 2013]
- Half a Million DVDs of Data Stored in Gram of DNA [Last Updated On: January 25th, 2013] [Originally Added On: January 25th, 2013]
- Jayy Star Feat DNA The Heredity (Don't Need Em) - Video [Last Updated On: February 10th, 2013] [Originally Added On: February 10th, 2013]
- Jayy Star Feat DNA The Heredity (Don't Need Em) - Video [Last Updated On: February 10th, 2013] [Originally Added On: February 10th, 2013]
- DNA evidence clears Texas man convicted in '81 killing [Last Updated On: February 12th, 2013] [Originally Added On: February 12th, 2013]
- DNA evidence clears Texas man convicted in '81 killing [Last Updated On: February 12th, 2013] [Originally Added On: February 12th, 2013]
- DNA Digital Videos presents EPIC Promo - Video [Last Updated On: February 16th, 2013] [Originally Added On: February 16th, 2013]
- 'Activating' RNA takes DNA on a loop through time and space [Last Updated On: February 18th, 2013] [Originally Added On: February 18th, 2013]
- 'Activating' RNA takes DNA on a loop through time and space [Last Updated On: February 18th, 2013] [Originally Added On: February 18th, 2013]
- New HTC One (Droid DNA) - Hands On UK - Video [Last Updated On: February 20th, 2013] [Originally Added On: February 20th, 2013]
- What is Brand DNA? BLVCK SCVLE Case Study - Video [Last Updated On: October 2nd, 2013] [Originally Added On: October 2nd, 2013]
- Nanded Train Accident: DNA test reveals mix up of Accident Dead Bodies | 10tv - Video [Last Updated On: January 5th, 2014] [Originally Added On: January 5th, 2014]
- DNA links executed convict to 1984 triple murder [Last Updated On: January 11th, 2014] [Originally Added On: January 11th, 2014]
- D-SPillz ft. Chucc Dizzle, DNA, Maniphest DestNE - Wishing Well (FREE DL LINK) - Video [Last Updated On: January 16th, 2014] [Originally Added On: January 16th, 2014]
- NOVA Extract Your DNA PBS359 - Video [Last Updated On: January 17th, 2014] [Originally Added On: January 17th, 2014]
- DNA:DECODE- Joe Rogan // ADN:DÉCODÉ- Joe Rogan - Video [Last Updated On: January 27th, 2014] [Originally Added On: January 27th, 2014]
- Campagna informativa "Banca Dati Nazionale DNA" - Video [Last Updated On: February 6th, 2014] [Originally Added On: February 6th, 2014]
- Congress cornered by BJP and AAP protests outside Arun ... [Last Updated On: February 10th, 2014] [Originally Added On: February 10th, 2014]
- DNA Test May Gauge Risk of Prostate Cancer's Return [Last Updated On: April 10th, 2014] [Originally Added On: April 10th, 2014]
- Blocking DNA repair mechanisms could improve radiation therapy for deadly brain cancer [Last Updated On: April 10th, 2014] [Originally Added On: April 10th, 2014]
- DNA matches Texas inmate in Houston cold cases [Last Updated On: April 10th, 2014] [Originally Added On: April 10th, 2014]
- Wisconsin Sheriff: DNA Ties Man to 1997 Slaying [Last Updated On: April 10th, 2014] [Originally Added On: April 10th, 2014]
- DNA ties man to 1997 murder of teen runaway [Last Updated On: April 10th, 2014] [Originally Added On: April 10th, 2014]
- DNA to pick out suspect, warts and all [Last Updated On: April 10th, 2014] [Originally Added On: April 10th, 2014]
- DNA-based logic gates operate inside cockroach cells [Last Updated On: April 10th, 2014] [Originally Added On: April 10th, 2014]
- DNA - Simple English Wikipedia, the free encyclopedia [Last Updated On: April 10th, 2014] [Originally Added On: April 10th, 2014]
- Deoxyribonucleic Acid (DNA) Fact Sheet - National Human ... [Last Updated On: April 10th, 2014] [Originally Added On: April 10th, 2014]
- What is DNA? - Genetics Home Reference - Your guide to ... [Last Updated On: April 10th, 2014] [Originally Added On: April 10th, 2014]
- DNA - Wikipedia, the free encyclopedia [Last Updated On: April 10th, 2014] [Originally Added On: April 10th, 2014]
- S k y p i feat Dodo - Postav sa zo dna (Official Video ryvok.... ) - Video [Last Updated On: April 10th, 2014] [Originally Added On: April 10th, 2014]
- Highlights: Eugenia Naro-Maciel, CUNY SI -- DNA Barcoding Freshwater Communities at Former Landfill - Video [Last Updated On: April 10th, 2014] [Originally Added On: April 10th, 2014]
- Highlights: George Ude, DNA Barcoding Projects at Bowie State and Godfrey Okoye Universities - Video [Last Updated On: April 10th, 2014] [Originally Added On: April 10th, 2014]
- Wonder of DNA 4/10/14 @ 8:00 pm EST - Video [Last Updated On: April 10th, 2014] [Originally Added On: April 10th, 2014]
- French police: all men at HS give DNA for rape case or be arrested [Last Updated On: April 15th, 2014] [Originally Added On: April 15th, 2014]
- French Polices Plan To DNA Test 500 High Schoolers Wouldnt Fly In U.S. [Last Updated On: April 15th, 2014] [Originally Added On: April 15th, 2014]
- 527 potential suspects in French high school rape lead to mass DNA test [Last Updated On: April 15th, 2014] [Originally Added On: April 15th, 2014]
- French authorities carry out DNA dragnet in school rape case [Last Updated On: April 15th, 2014] [Originally Added On: April 15th, 2014]
- DNA - New World Encyclopedia [Last Updated On: April 15th, 2014] [Originally Added On: April 15th, 2014]
- Motion Design Elemen DNA Strand Animation HD 2014 - Video [Last Updated On: April 15th, 2014] [Originally Added On: April 15th, 2014]
- 3D Pathway DNA Animation - Kawa 2014 - Video [Last Updated On: April 15th, 2014] [Originally Added On: April 15th, 2014]
- DNA Technologies - Video [Last Updated On: April 15th, 2014] [Originally Added On: April 15th, 2014]
- Assassin's Creed 4 [THC] vs [DNA] Competitive Artifact Assault - Video [Last Updated On: April 15th, 2014] [Originally Added On: April 15th, 2014]
- 12) Dr.Rasheed 10/04/2014 [DNA : Mitochondrial DNA - Replication in prokaryotes] - Video [Last Updated On: April 15th, 2014] [Originally Added On: April 15th, 2014]
- DNA Activation Plan Upgrades - Video [Last Updated On: April 15th, 2014] [Originally Added On: April 15th, 2014]
- DNA Wealth Blueprint - Andrew Fox + Peter Parks | DNA Wealth Blueprint Video Review - Video [Last Updated On: April 15th, 2014] [Originally Added On: April 15th, 2014]
- "DNA" das pessoas - Video [Last Updated On: April 15th, 2014] [Originally Added On: April 15th, 2014]
- Mass DNA sweep in privacy-loving France: Why no backlash? [Last Updated On: April 15th, 2014] [Originally Added On: April 15th, 2014]
- Monster DNA In-Earphones Unboxing - Video [Last Updated On: April 15th, 2014] [Originally Added On: April 15th, 2014]
- DJ RODRIGO - NOS SCRATCHS - Video [Last Updated On: April 15th, 2014] [Originally Added On: April 15th, 2014]
- [DBS] DNA MEP - Part 14 - Video [Last Updated On: April 15th, 2014] [Originally Added On: April 15th, 2014]
- Growing Up Poor Is Bad For Your DNA - Video [Last Updated On: April 15th, 2014] [Originally Added On: April 15th, 2014]
- RUG400 DNA-experience - Video [Last Updated On: April 15th, 2014] [Originally Added On: April 15th, 2014]
- RNA polymerase transcribing RNA from DNA - Video [Last Updated On: April 15th, 2014] [Originally Added On: April 15th, 2014]
- StorageDNA Discusses DNA Evolution 3.5 @ NAB 2014, Booth: SL10621 - Video [Last Updated On: April 15th, 2014] [Originally Added On: April 15th, 2014]
- DNA:DECODE- The Bronx // ADN:DCOD- Le Bronx - Video [Last Updated On: April 15th, 2014] [Originally Added On: April 15th, 2014]
- DNA Wealth Blueprint Scam? - Video [Last Updated On: April 15th, 2014] [Originally Added On: April 15th, 2014]
- Unlocking DNA technology in Nigeria - Video [Last Updated On: April 15th, 2014] [Originally Added On: April 15th, 2014]
- Mass DNA sweep in privacy-loving France: Why no backlash? (+video) [Last Updated On: April 16th, 2014] [Originally Added On: April 16th, 2014]
- 13) Dr.Rasheed 13/04/2014 [DNA : Replication of DNA] - Video [Last Updated On: April 16th, 2014] [Originally Added On: April 16th, 2014]
- Medbone | Empresa com apoio da DNA Cascais exporta para mais de 40 pases - Video [Last Updated On: April 16th, 2014] [Originally Added On: April 16th, 2014]
- 16) Dr.Abbas 16 [DNA : RNA synthesis in prokaryotes, eukaryotes & Synthesis of mRNA] - Video [Last Updated On: April 16th, 2014] [Originally Added On: April 16th, 2014]
- [DNA Wealth Blueprint Review] See DNA Wealth Blueprint Bonus Strategies For Facebook CPA Marketing - Video [Last Updated On: April 16th, 2014] [Originally Added On: April 16th, 2014]
- DnA's Evolution (live 4/11/14) - Part 1 - Video [Last Updated On: April 16th, 2014] [Originally Added On: April 16th, 2014]
- Attack of the B team w/tgudge- Dino DNA - Video [Last Updated On: April 16th, 2014] [Originally Added On: April 16th, 2014]
- Criminals Beware: Faces Recreated With ONLY DNA - Video [Last Updated On: April 16th, 2014] [Originally Added On: April 16th, 2014]
- Me Salva! GEN03 - Replicao do DNA - Parte 2 - Video [Last Updated On: April 16th, 2014] [Originally Added On: April 16th, 2014]
- Timolia Servervorstellung [2/5] | DNA #1 | DeusExMachina x TeMasket - Video [Last Updated On: April 17th, 2014] [Originally Added On: April 17th, 2014]
- Building on the DNA of Discovery: Vision Concept's exterior - Video [Last Updated On: April 17th, 2014] [Originally Added On: April 17th, 2014]
- DNA Tests Over Rape - Video [Last Updated On: April 17th, 2014] [Originally Added On: April 17th, 2014]
- Hydrogen bonding in DNA - Video [Last Updated On: April 17th, 2014] [Originally Added On: April 17th, 2014]
- How Is Your Emotional DNA Impacting Your Relationship? - Video [Last Updated On: April 17th, 2014] [Originally Added On: April 17th, 2014]
- Nucleic Acids 20: DNA to RNA to Proteins - Video [Last Updated On: April 17th, 2014] [Originally Added On: April 17th, 2014]
- Nucleic Acids 13: Even More About 3D Structure of DNA - Video [Last Updated On: April 17th, 2014] [Originally Added On: April 17th, 2014]