definition of double helix
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double helix Definition of double helix. : a helix or spiral consisting of two strands in the surface of a cylinder that coil around its axis; especially : the structural arrangement of DNA in space that consists of paired polynucleotide strands stabilized by cross-links between purine and pyrimidine bases — compare alpha-helix, watson-crick model.
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double helix double helix n. The coiled structure of a double-stranded DNA molecule in which strands linked by hydrogen bonds form a spiral configuration. Also called DNA helix, Watson-Crick helix.
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Concept 19 The DNA molecule is shaped like a twisted ladder. X-ray crystallography provided the final clue that the DNA molecule is a double helix, shaped like a twisted ladder. In 1953, the race to determine how these pieces fit together in a three-dimensional structure was won by James Watson and Francis Crick at the Cavendish Laboratory in Cambridge, England.They showed that alternating deoxyribose and phosphate molecules form the twisted uprights of the DNA ladder.The rungs of the ladder are formed by complementary pairs of nitrogen bases — A always paired with T and G always paired with C.-ray crystallography provided the final clue that the DNA molecule is a double helix, shaped like a twisted ladder. In 1953, the race to determine how these pieces fit together in a three-dimensional structure was won by James Watson and Francis Crick at the Cavendish Laboratory in Cambridge, England.
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Alpha helix The alpha helix (α-helix) is a common motif in the secondary structure of proteins and is a righthand-coiled or spiral conformation (helix) in which every backbone N-H group donates a hydrogen bond to the backbone C=O group of the amino acid located three or four residues earlier along the protein sequence.
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double helix The chemical backbones of the double helix are made up of sugar and phosphate molecules that are connected by chemical bonds, known as sugar-phosphate backbones. The two helical strands are connected through interactions between pairs of nucleotides, also called base pairs.
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The Unsung Hero Who Discovered The Double Helix It's commonly believed that James Watson and Francis Crick discovered the double helix shape of DNA. But in fact, they based their work on one of their colleagues at King's College in London - Rosalind Franklin, an x-ray diffraction expert whose images of DNA proteins in the early 1950s revealed a helix shape.
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Definitions &Translations The common helix is the curve formed by the thread of the ordinary screw. It is distinguished from the spiral, all the convolutions of which are in the plane. Helix (noun). a caulicule or little volute under the abacus of the Corinthian capital. Helix (noun). the incurved margin or rim of the external ear.
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- Wiktionary (0.00 / 0 votes) Rate this definition: helix (Noun). A curve on the surface of a cylinder or cone such that its angle to a plane perpendicular to the axis is constant; the three-dimensional curve seen in a screw or a spiral staircase. helix (Noun). A small volute under the abacus of a Corinthian capital.
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- James Watson was a pioneer molecular biologist who is credited, along with Francis Crick and Maurice Wilkins, with discovering the double helix structure of the DNA molecule.
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The Discovery of the  Molecular Structure of DNA - The Double Helix The Discovery of the Molecular Structure of DNA - The Double Helix A Scientific Breakthrough. The sentence This structure has novel features which are of considerable biological interest may be one of science's most famous understatements.
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The Double Helix The Double Helix. It contains two polynucleotide strands wound around each other. The backbone of each consists of alternating deoxyribose and phosphate groups. The phosphate group bonded to the 5' carbon atom of one deoxyribose is covalently bonded to the 3' carbon of the next.
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DNA Structure and Function 1 Watson-Crick model of DNA; double helix. 2  The double in the double helix means that DNA is found in a double-stranded form - 2 single-stranded chains of DNA stuck to each other via hydrogen bonding of the base pairs. The double in the double helix means that DNA is found in a double-stranded form - 2 single-stranded chains of DNA stuck to each other via hydrogen bonding of the base pairs. 2  The 2 single-strands are anti-parallel to each other. 3  Going from 5' to 3' of one strand means going from 3' to 5' of the other strand.
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- The double helix resembles a ladder, with two parallel sides and pairs of bases that match up and form the rungs. These “rungs” are called nucleotides, and are made up of a sugar (in the case of DNA, that sugar is dexoyribose), one phosphate group, and a nitrogenous base. That nitrogenous base is what we are interested in today.
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Nucleic acid double helix The DNA double helix polymer of nucleic acids, held together by nucleotides which base pair together. In B-DNA, the most common double helical structure, the double helix is right-handed with about 10–10.5 base pairs per turn.This translates into about 20-21 nucleotides per turn. The double helix structure of DNA contains a major groove and minor groove.he previous model was triple-stranded DNA. The realization that the structure of DNA is that of a double-helix elucidated the mechanism of base pairing by which genetic information is stored and copied in living organisms and is widely considered one of the most important scientific discoveries of the 20th century.
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double helix The chemical backbones of the double helix are made up of sugar and phosphate molecules that are connected by chemical bonds, known as sugar-phosphate backbones. The two helical strands are connected through interactions between pairs of nucleotides, also called base pairs.n 1953, Francis Crick and James Watson first described the molecular structure of DNA, which they called a double helix, in the journal Nature.
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Nucleic acid double helix The DNA double helix polymer of nucleic acids, held together by nucleotides which base pair together. In B-DNA, the most common double helical structure, the double helix is right-handed with about 10–10.5 base pairs per turn.This translates into about 20-21 nucleotides per turn.The double helix structure of DNA contains a major groove and minor groove.wo complementary regions of nucleic acid molecules will bind and form a double helical structure held together by base pairs. In molecular biology, the term double helix refers to the structure formed by double-stranded molecules of nucleic acids such as DNA.
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- A molecule of DNA is double-stranded. The molecule has the shape of a double helix, typically right handed (B form DNA). The DNA molecule consists of two complementary strands oriented in an antiparallel fashion. Each strand is composed of nucleotides.
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duplex Definition of duplex. 1  1a : having two principal elements or parts : double, twofoldb : having two complementary polynucleotide strands of DNA or of DNA and RNA. 2  2 : allowing telecommunication in opposite directions simultaneously.
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- 1 The two strands are wound round each other to form a double helix.  The two strands are joined together by hydrogen bonds between the bases. The bases therefore form base pairs, which are like rungs of a ladder.
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Nucleic acid double helix The term entered popular culture with the publication in 1968 of The Double Helix: A Personal Account of the Discovery of the Structure of DNA, by James Watson. The DNA double helix polymer of nucleic acids, held together by nucleotides which base pair together. In B-DNA, the most common double helical structure, the double helix is right-handed with about 10–10.5 base pairs per turn. This translates into about 20-21 nucleotides per turn.
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- Each strand of DNA in the double helix can serve as a pattern for duplicating the sequence of bases. This is critical when cells divide because each new cell needs to have an exact copy of the DNA present in the old cell.NA is a double helix formed by base pairs attached to a sugar-phosphate backbone. DNA, or deoxyribonucleic acid, is the hereditary material in humans and almost all other organisms.
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- . Each DNA molecule consists of two twisted strands of bases that form a shape called a double helix. The two strands are held together by hydrogen bonds between pairs of bases. When a cell grows and divides into two, it first has to make a duplicate copy of each DNA molecule.
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DNA Definition: Shape, Replication, and Mutation Share. By Regina Bailey. Definition: DNA (deoxyribonucleic acid) is a type of macromolecule known as a nucleic acid. It is shaped like a twisted double helix and is composed of long strands of alternating sugars and phosphate groups, along with nitrogenous bases (adenine, thymine, guanine and cytosine). It is organized into structures called chromosomes and housed within the nucleus of our cells.
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double helix double helix. The three-dimensional structure of double-stranded DNA, in which polymeric nucleotide strands whose complementary nitrogen bases are linked by hydrogen bonds form a helical configuration. The two DNA strands are oriented in opposite directions. double helix in Culture.
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Medical Definition of Deoxyribonucleic acid DNA: Deoxyribonucleic acid. One of two types of molecules that encode genetic information. (The other is RNA. In humans DNA is the genetic material; RNA is transcribed from it. In some other organisms, RNA is the genetic material and, in reverse fashion, the DNA is transcribed from it.) DNA is a double-stranded molecule held together by weak hydrogen bonds between base pairs of nucleotides. The molecule forms a double helix in which two strands of DNA spiral about one other. The double helix looks something like an immensely long ladder twisted into a helix, or coil.
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- is a double helix where one strand coils around the other. The helix is unwound and rewound every now and then to take out its information, which requires local alteration of the helical structure, resulting in the super­ coiling of DNA. For replication, all the coils must be unwound at least once, and two daughter molecules are