structure (struk´chur)

1. The arrangement of the details of a part; the manner of formation of a part. 2. A tissue or formation made up of different but related parts. 3. In chemistry, the specific connections of the atoms in a given molecule. [L. structura, fr. struo, pp. structus, to build]
brush heap s.haphazard interlocking of fibrils in a gel or hydrocolloid impression material.
chi s.a joint between two DNA duplex molecules. See also chi sequence.
cointegrate s.a s. of DNA produced by the fusion of two replicons, one possessing a transposon.
complementary s.'ss.'s that define one another; e.g., the two strands of duplex DNA.
crystal s.the arrangement in space and the interatomic distances and angles of the atoms in crystals, usually determined by x-ray diffraction measurements.
denture-supporting s.'sthe tissues, teeth, and/or residual ridges, which serve as the foundation for removable partial or complete dentures.
fine s.ultrastructure
gel s.brush heap s. of fibrils giving firmness to hydrocolloids.
Holliday s.Holliday junction
primary a macromolecule, the sequence of sub-units that make up that macromolecule; e.g., the amino acid sequence of a protein.
quaternary s.the three-dimensional arrangement and constitution of a multimeric (i.e., a substance containing more than one biopolymer) macromolecule; e.g., the a2beta2 tetramer of hemoglobin A.
secondary s.the localized arrangement in space of regions of a biopolymer; often these types of s.'s are regular and recurring along one dimension; e.g., the a-helix often found in proteins.
tertiary s.the three-dimensional configuration of a biopolymer.
tuboreticular s.tubules 20-30 nm in length that lie within cisterns of smooth endoplasmic reticulum; observed in connective tissue diseases such as SLE, and in various cancers and virus infections.


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