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Helices
A helix (; ) is a shape like a cylindrical coil spring or the thread of a machine screw. It is a type of smoothness (mathematics), smooth space curve with tangent lines at a constant angle to a fixed axis. Helices are important in biology, as the DNA molecule is formed as double helix, two intertwined helices, and many proteins have helical substructures, known as alpha helix, alpha helices. The word ''helix'' comes from the Greek language, Greek word , "twisted, curved". A "filled-in" helix – for example, a "spiral" (helical) ramp – is a surface called a ''helicoid''. Properties and types The pitch of a helix is the height of one complete helix turn (angle), turn, measured parallel to the axis of the helix. A double helix consists of two (typically congruence (geometry), congruent) helices with the same axis, differing by a translation along the axis. A circular helix (i.e. one with constant radius) has constant band curvature and constant Torsion of curves, torsion. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alpha Helix
An alpha helix (or α-helix) is a sequence of amino acids in a protein that are twisted into a coil (a helix). The alpha helix is the most common structural arrangement in the Protein secondary structure, secondary structure of proteins. It is also the most extreme type of local structure, and it is the local structure that is most easily predicted from a sequence of amino acids. The alpha helix has a right-handed helix conformation in which every backbone amino, N−H group hydrogen bonds to the backbone carbonyl, C=O group of the amino acid that is four residue (biochemistry), residues earlier in the protein sequence. Other names The alpha helix is also commonly called a: * Pauling–Corey–Branson α-helix (from the names of three scientists who described its structure) * 3.613-helix because there are 3.6 amino acids in one ring, with 13 atoms being involved in the ring formed by the hydrogen bond (starting with amidic hydrogen and ending with carbonyl oxygen) Discovery ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Helix
A helix (; ) is a shape like a cylindrical coil spring or the thread of a machine screw. It is a type of smooth space curve with tangent lines at a constant angle to a fixed axis. Helices are important in biology, as the DNA molecule is formed as two intertwined helices, and many proteins have helical substructures, known as alpha helices. The word ''helix'' comes from the Greek word , "twisted, curved". A "filled-in" helix – for example, a "spiral" (helical) ramp – is a surface called a '' helicoid''. Properties and types The pitch of a helix is the height of one complete helix turn, measured parallel to the axis of the helix. A double helix consists of two (typically congruent) helices with the same axis, differing by a translation along the axis. A circular helix (i.e. one with constant radius) has constant band curvature and constant torsion. The slope of a circular helix is commonly defined as the ratio of the circumference of the circular cylinder that it ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Double Helix
In molecular biology, the term double helix refers to the structure formed by base pair, double-stranded molecules of nucleic acids such as DNA. The double Helix, helical structure of a nucleic acid complex arises as a consequence of its Nucleic acid secondary structure, secondary structure, and is a fundamental component in determining its Nucleic acid tertiary structure, tertiary structure. The structure was discovered by Rosalind Franklin and her student Raymond Gosling, Maurice Wilkins, James Watson, and Francis Crick, while the term "double helix" entered popular culture with the 1968 publication of Watson's ''The Double Helix, The Double Helix: A Personal Account of the Discovery of the Structure of DNA''. The DNA double helix biopolymer of nucleic acid is held together by nucleotides which base pair together. In B-DNA, the most common double helical structure found in nature, the double helix is right-handed with about 10–10.5 base pairs per turn. The double helix struc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spiral
In mathematics, a spiral is a curve which emanates from a point, moving further away as it revolves around the point. It is a subtype of whorled patterns, a broad group that also includes concentric objects. Two-dimensional A two-dimensional, or plane, spiral may be easily described using polar coordinates, where the radius r is a monotonic continuous function of angle \varphi: * r=r(\varphi)\; . The circle would be regarded as a degenerate case (the function not being strictly monotonic, but rather constant). In ''x-y-coordinates'' the curve has the parametric representation: * x=r(\varphi)\cos\varphi \ ,\qquad y=r(\varphi)\sin\varphi\; . Examples Some of the most important sorts of two-dimensional spirals include: * The Archimedean spiral: r=a \varphi * The hyperbolic spiral: r = a/ \varphi * Fermat's spiral: r= a\varphi^ * The lituus: r = a\varphi^ * The logarithmic spiral: r=ae^ * The Cornu spiral or ''clothoid'' * The Fibonacci spiral and golden spiral * ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Springs 016
Spring(s) may refer to: Common uses * Spring (season), a season of the year * Spring (device), a mechanical device that stores energy * Spring (hydrology), a natural source of water * Spring (mathematics), a geometric surface in the shape of a helically coiled tube * Spring (political terminology), often used to name periods of political liberalization * Springs (tide), in oceanography, the maximum tide, occurs twice a month during the full and new moon Places * Spring (Milz), a river in Thuringia, Germany * Spring, Alabel, a barangay unit in Alabel, Sarangani Province, Philippines * Șpring, a commune in Alba County, Romania * Șpring (river), a river in Alba County, Romania * Springs, Gauteng, South Africa * Springs, the location of Dubai British School, Dubai * Spring Village, Saint Vincent and the Grenadines * Spring Village, Shropshire, England United States * Springs, New York, a part of East Hampton, New York * Springs, Pennsylvania, an unincorporated community ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Conic Helix
In mathematics, a conical spiral, also known as a conical helix, is a space curve on a right circular cone, whose Orthographic projection, floor projection is a plane spiral. If the floor projection is a logarithmic spiral, it is called ''conchospiral'' (from conch). Parametric representation In the x-y-plane a spiral with parametric representation : x=r(\varphi)\cos\varphi \ ,\qquad y=r(\varphi)\sin\varphi a third coordinate z(\varphi) can be added such that the space curve lies on the cone with equation \;m^2(x^2+y^2)=(z-z_0)^2\ ,\ m>0\; : * x=r(\varphi)\cos\varphi \ ,\qquad y=r(\varphi)\sin\varphi\ , \qquad \color \ . Such curves are called conical spirals. They were known to Pappos. Parameter m is the slope of the cone's lines with respect to the x-y-plane. A conical spiral can instead be seen as the orthogonal projection of the floor plan spiral onto the cone. Examples : 1) Starting with an ''archimedean spiral'' \;r(\varphi)=a\varphi\; gives the conical spiral ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
