Because it contains the directions for assembling the components of the cell, DNA is often thought of as the "instruction book" for assembling life.
DNA (deoxyribonucleic acid) is the nucleic acid located in the nucleus of a cell. It contains the genetic information that controls all cell activities and has the unique ability to replicate itself. Because it contains the directions for assembling the components of the cell, DNA is often thought of as the "instruction book" for assembling life. DNA is organized into structures called chromosomes. At various points along the molecule, stretches of DNA are grouped into functional regions called genes. Genes can encode for a protein or regulate the expression of other genes. Every cell contains the entire complement of DNA, which, in humans, consists of more than 6 billion base pairs. The chemical structure of DNA was discovered in 1953 by James Watson and Francis Crick. Watson and Crick concluded that DNA is a double helixâ€š a twisted ladder, with two phosphate-based backbones and "runged" nucleotides that pair. Attached to the backbone are molecules called nucleotides. Nucleotides attach in pairs (or base pairs), with adenine (A) pairing with thymine (T) and guanine (G) with cytosine (C). The long sequence formed by these four base pairs is, essentially, the genetic code. Shorter sequences of the code are transcribed into RNA, and translated into a sequence of amino acids â€“ the building blocks of proteins.
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- ID: 1445
- Source: DNALC.G2C
Blocks to bases, DNA Has Four Units.
Image depicting DNA helix model and table.
James Watson talks about how he worked out the base pairing of DNA.
15492. Discovering the double helix structure of DNA, James Watson, video with 3D animation and narration
James Watson used cardboard cutouts representing the shapes of the DNA bases to figure out how bases pair.
James Watson and Francis Crick's 1953 Nature paper.
Deoxyribose and phosphate molecules form the uprights and nucleotide pair form the rungs of the DNA ladder.
James Watson and Francis Crick explain how they solved the structure of DNA. Erwin Chargaff explain how he measured the levels of each of the four nitrogenous bases.
Francis Crick describes RNA and its role and Paul Zamecnick explains protein synthesis.
DNA base pairs
Friedrich Miescher and Phoebus Levene research nuclein, protein. and DNA.