- butterfly f. a broad triangular f. that is commonly present in comminuted fractures of the diaphysis.
- Fab f. the antigen-binding f. of an immunoglobulin molecule, consisting of both a light chain and part of a heavy chain. SYN: Fab piece.
- Fc f. the crystallizable f. of an immunoglobulin molecule composed of part of the heavy chains and responsible for binding to antibody receptors (Fc receptor) on cells and the Clq component of complement. SYN: Fc piece.
- Klenow f. carboxyl terminal f. of DNA polymerase I, contains polymerase as well as 3′ → 5′ exonuclease activity to edit out mismatches.
- Okazaki f. a relatively short (100–2000 bp in Escherichia coli and 100–200 bp in mammals) f. of DNA that is later joined by DNA ligase to allow for 3′ → 5′ overall chain growth during replication.
- one-carbon f. the formyl group or the methyl group that takes part in transformylation or transmethylation reactions; by means of these reactions, a group containing a single carbon atom is added to a compound being biosynthesized, adding a methyl group (as in thymidine formation), adding a hydroxymethyl group (as in serine biosynthesis), or closing a ring (as in purine formation).
- two-carbon f. the acetyl group (CH3CO–) that takes part in transacetylation reactions with coenzyme A as carrier; commonly referred to as acetate or acetic acid, from which it is derived.
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frag·ment 'frag-mənt n a part broken off or detached
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frag·ment (fragґmənt) one of the small pieces into which a larger entity has been broken.Medical dictionary. 2011.