helix


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helix

 [he´liks] (pl. he´lices, helixes) (Gr.)
1. a winding structure; see also coil and spiral.
2. the superior and posterior free margin of the pinna of the ear.
α-helix (alpha helix) the complex structural arrangement of parts of protein molecules in which a single polypeptide chain forms a right-handed helix.
double helix (Watson-Crick helix) the structure of deoxyribonucleic acid (DNA), consisting of two coiled chains, each of which contains information completely specifying the other chain.

he·lix

, pl.

hel·i·ces

(hē'liks, hel'i-sēz), [TA] Do not confuse this word with spiral.
1. The margin of the auricle; a folded rim of cartilage forming the upper part of the anterior, the superior, and the greater part of the posterior edges of the auricle.
2. A line in the shape of a coil (or a spring, or the threads on a bolt), each point being equidistant from a straight line that is the axis of the cylinder in which each point of the helix lies.
[L. fr. G. helix, a coil]

helix

/he·lix/ (he´liks) pl. he´lices, helixes   [Gr.]
1. spiral (2).
2. the superior and posterior free margin of the pinna of the ear.

α-helix , alpha helix the structural arrangement of parts of protein molecules in which a single polypeptide chain forms a right-handed helix stabilized by intrachain hydrogen bonds.
double helix , Watson-Crick helix a representation of the structure of DNA, consisting of two coiled chains arranged antiparallel to each other, each containing information completely specifying the other chain.

helix

(hē′lĭks)
n. pl. he·lixes or helices (hĕl′ĭ-sēz′, hē′lĭ-)
1. Mathematics A three-dimensional curve that lies on a cylinder or cone, so that its angle to a plane perpendicular to the axis is constant.
2. A spiral form or structure.
3. Anatomy The folded rim of skin and cartilage around most of the outer ear.
4. Architecture A volute on a Corinthian or Ionic capital.
v. he·lixed, he·lixing, he·lixes
v.tr.
To move or position (something) into the shape of a helix.
v.intr.
1. To have the shape of a helix.
2. To move along a helical course; spiral.

helix

[hē′liks]
Etymology: Gk, coil
1 a coiled, spiral-like formation characteristic of many organic molecules, such as DNA and certain proteins..
2 the large outside rim of the auricle.
Anatomy The superior and posterior free margin of the pinna of the ear
Molecular biology A winding structural motif for nucleic acids and proteins

he·lix

, pl. helixes, pl. helices (hē'liks, -ĕz, hel'i-sēz)
1. [TA] The margin of the auricle; a folded rim of cartilage forming the upper part of the anterior, the superior, and the greater part of the posterior edges of the auricle.
2. A line in the shape of a coil (or a spring, or the threads on a bolt), each point being equidistant from a straight line that is the axis of the cylinder in which each point of the helix lies. usage note: Often mistakenly applied to a spiral.
[L. fr. G. helix, a coil]

helix

The folded margin of the outer ear. The form of the helix is determined by the underlying cartilage.

helix

(pl. helixes or helices) a form of spiral in which any point is at the same distance from the central axis. RNA molecules have a single helix, DNA is a double helix.

helix

1. a coiled structure.
2. the free margin of the pinna of the ear.

α-helix, alpha-helix
the folding arrangement of parts of protein molecules in which a single polypeptide chain forms a right-handed helix.
helix destabilizing proteins
proteins that bind in a cooperative manner to DNA single-strands during DNA replication and help open up the replication fork. Called also single-strand DNA binding proteins.
double helix
the native state of deoxyribonucleic acid (DNA), in which two antiparallel chains with complementary nucleotide sequences are wound around each other. The DNA molecule consists of two sugar-phosphate strands with the nucleotide base pairs stacked between them. The orientation of the two strands is antiparallel, i.e. 5′→3′ directions are opposite. Called also Watson-Crick helix.
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