methyl group
Q blood group system
| mismatch repair | <molecular biology> A DNA repair system that detects and replaces wrongly paired, mismatched, bases in newly replicated DNA. E. Coli has a mismatch correction enzyme coded for by three genes mutH, mutL and mutS, that is directed to the newly synthesised strand and removes a segment of that strand including the incorrect nucleotide. The gap is then filled by DNA polymerase. (18 Nov 1997) |
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| hernia repair | <surgery> The surgical repair of a hernia. This surgery can be done under local or general anaesthesia. May be performed using a conventional incision or using a fibreoptic laparoscope. (27 Sep 1997) |
| SOS repair | A system that repairs severely damaged bases in DNA by base excision and replacement, even if there is no template to guide base selection. This process is a last resort for repair, and is often the cause of mutations. Synonym: error-prone repair. (05 Mar 2000) |
| dental prosthesis repair | The process of reuniting or replacing a broken or worn dental prosthesis or its part. (12 Dec 1998) |
| denture repair | The process of reuniting or replacing broken or worn parts of a denture. (12 Dec 1998) |
| DNA repair | <molecular biology> Each cell has a series of special enzymes to correct the errors in DNA structure and sequence. This protects genetic information against environmental damage and replication errors and restore the DNA to its original state. (25 Jun 1999) |
| DNA repair gene | A gene engaged in DNA repair. When a DNA repair gene is altered, mutations pile up throughout the DNA. (12 Dec 1998) |
| DNA repair pathway | The sequence of steps in the repair of DNA. Each step is governed by an enzyme. (12 Dec 1998) |
| error-prone repair | <molecular biology> A type of DNA repair which occurs when both nucleotides in a base pair are missing, such that it is not possible to maintain accuracy. In general, the repair proteins replace the missing nucleotides randomly. The idea is that bad DNA is better than no DNA at all. (06 Mar 1998) |
| excision repair | <molecular biology> Mechanism for the repair of environmental damage to one strand of DNA (loss of purines due to thermal fluctuations, formation of pyrimidine dimers by UV irradiation). The site of damage is recognised, excised by an endonuclease, the correct sequence is copied from the complementary strand by a polymerase and the ends of this correct sequence are joined to the rest of the strand by a ligase. The term is sometimes restricted to bacterial systems where the polymerase also acts as endonuclease. (11 Nov 1997) |
| ABO blood group | <haematology> The major human blood type system which describes the oligosaccharide glycoprotein antigens found on the surface of human blood cells. According to the type of antigen present, a person may be assigned a blood type of A, B, AB or O. A second type of antigen, the Rh factor, renders a positive or negative blood type. The ABO blood group system is important because it determines who can donate blood to or accept blood from whom. Type A or AB blood will cause an immune reaction in people with type B blood and type B and AB blood will cause a reaction in people with type A blood. Conversely, type O blood has no A or B antigens, so people with type O blood are universal donors. And since AB blood already produces both antigens, people who are type AB can accept any of the other blood types without suffering an immune reaction. (04 Jul 1999) |
| actinobacteria group | A group of gram-positive, heterogeneous bacteria. This group encompasses a range of morphologically, physiologically, and chemically different organisms and includes bacteria that form cocci, short rods, irregular rods, and mycelia that fragment. (12 Dec 1998) |
| alkyl group | <chemistry> A funtional group on an organic molecule which is derived from an alkane which has lost a hydrogen atom. (13 Nov 1997) |
| aluminum group | Aluminum, boron, gallium, indium, and thallium. (05 Mar 2000) |
| amino group | <biochemistry> An -NH2 group. Organic compounds which have this group are called amines. (09 Oct 1997) |