| tertiary structure | <biochemistry, chemistry> The third level of structural organisation in a macromolecule. The primary structure of a protein (for example) is the amino acid sequence, the secondary structure is the folding of the peptide chain (alpha helical or beta pleated), the tertiary structure is the way in which the helices or sheets are folded or arranged to give the three dimensional structure of the protein. Quaternary structure refers to the arrangement of protomers in a multimeric protein. (13 Jan 1998) |
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| tuboreticular structure | 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. (05 Mar 2000) |
| fine structure | <pathology> General term to describe the level of organisation that is below the level of resolution of the light microscope. In practice, a shorthand term for structure observed using the electron microscope, although other techniques could give information about structure in the sub micrometre range. (18 Nov 1997) |
| fine structure mapping | A technique of DNA mapping which makes use of extremely rare recombination events where the crossing over occurs between two genes or two alleles of a gene that are only a few nucleotides apart. (09 Oct 1997) |