| tumour initiation | <cell biology, oncology> First stage of tumour development. See: tumour progression. (18 Nov 1997) |
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| peptide chain initiation | The process whereby the formation of a peptide chain is started. This process requires (1) the 30s subunit, (2) the mRNA coding for the polypeptide to be made, (3) met-trnai, (4) initiation factors, and (5) GTP. (12 Dec 1998) |
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| peptide initiation factors | Protein factors uniquely required during the initiation phase of protein synthesis. (12 Dec 1998) |
| initiation | 1. The first stage of tumour induction by a carcinogen; subtle alteration of cells by exposure to a carcinogenic agent so that they are likely to form a tumour upon subsequent exposure to a promoting agent (promotion). 2. Starting point of replication or translation in macromolecule biosynthesis. 3. Start of chemical or enzymatic reaction. (05 Mar 2000) |
| initiation codon | The codon 5' AUG in mRNA, at which polypeptide synthesis is started. It is recognised by formylmethionyl tRNA in bacteria and by methionyl tRNA in eukaryotes. (18 Nov 1997) |
| initiation complex | Complex between mRNA, 30S ribosomal subunit and formyl methionyl tRNA that requires GTP and initiation factors to function. (18 Nov 1997) |
| initiation factor | One of several soluble proteins involved in the initiation of protein or RNA synthesis. (05 Mar 2000) |
| initiation factors | The set of catalytic proteins required, in addition to mRNA and ribosomes, for protein synthesis to begin. In bacteria three distinct proteins have been identified: if 1 (8 kD), IF 2 (75 kD) and IF 3 (30 kD). at least 6-8 proteins have been identified in eukaryotes. IFs 1 and 2 enhance the binding of initiator tRNA to the initiation complex. (18 Nov 1997) |
| initiation tRNA | TRNA in prokaryotes containing a formyl-methionyl residue that initiates translation. Synonym: formyl-methionyl-tRNA, starter tRNA. (05 Mar 2000) |
| acinar cell tumour | A solid and cystic tumour of the pancreas, occurring in young women; tumour cells contain zymogen granules. (05 Mar 2000) |
| acute splenic tumour | Acute splenitis, enlargement, and softening of the spleen, usually due to bacteraemia or severe bacterial toxaemia. (05 Mar 2000) |
| adenoid tumour | Adenoma, or neoplasm with glandlike spaces. (05 Mar 2000) |
| adenomatoid odontogenic tumour | A benign epithelial odontogenic tumour appearing radiographically as a well-circumscribed radiolucent-radiopaque lesion usually surrounding the crown of an impacted tooth in an adolescent or young adult; characterised histologically by columnar cells organised in a duct-like configuration interspersed with spindle-shaped cells and amyloid-like deposition that gradually undergoes dystrophic calcification. Synonym: adenoameloblastoma, ameloblastic adenomatoid tumour. (05 Mar 2000) |
| adenomatoid tumour | A small, circumscribed, benign tumour of the genital tract, composed of small glandlike spaces lined by flattened or cuboidal mesothelium-like cells. (12 Dec 1998) |
| adipose tumour | <oncology, tumour> Clumps of fat cells. Literally, fat cancer. These are benign tumours that can form in the breast. (16 Dec 1997) |
| adrenal gland tumour | <oncology> A benign tumour or adenoma, that usually results in the excess production of adrenal gland hormones. (27 Sep 1997) |