| lambda bacteriophage | <virology> Bacterial DNA virus, first isolated from E. Coli. Its structure is similar to that of the T even phages. Lambda genetic material consists of a double-stranded DNA molecule with 5' twelve-base-pair sticky ends, known as cos sites, which permit circularisation of the DNA molecule. It shows a lytic cycle and a lysogenic cycle and studies on the control of these alternative cycles have been very important for our understanding of the regulation of gene transcription. It is used as a cloning vector, accommodating fragments of DNA up to 15 kilobase pairs long. For larger pieces, the cosmid vector was constructed from its ends. (14 Mar 2000) |
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| bacteriophage lambda | <microbiology, virology> A bacteriophage, or virus which infects bacteria, that infects E. Coli. It has a complex set of regulatory mechanisms to determine whether it will quietly insert its DNA into the bacterial genome to become dormant and to be reproduced whenever the bacterium reproduces (to lysogenize), or whether it will hijack the bacterium's cellular machinery to reproduce itself and prepare to infect more bacteria, causing the bacterium to self-destruct shortly after infection (to lyse). Lambda is particularly useful to geneticists because parts of it can be used to introduce foreign DNA into the bacterial genome, it is a cloning vector. (09 Oct 1997) |
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| immunoglobulins, lambda-chain | One of the light chains of the immunoglobulins with a molecular weight of approximately 22 kD. They constitute about 40% of all light chains and can be recognised serologically as well as by their specific amino acid sequence. (12 Dec 1998) |
| exonuclease lambda | An exonuclease enzyme that removes nucleotides from the 5' end of duplex DNA which have 5'-phosphate groups attached to them. (09 Oct 1997) |
| lambda | 1. The name of the Greek letter lambda, corresponding with the English letter L, l. 2. <anatomy> The point of junction of the sagittal and lambdoid sutures of the skull. <zoology> Lambda moth, a moth so called from a mark on its wings, resembling the Greek letter. Origin: NL, fr. Gr. Source: Websters Dictionary (01 Mar 1998) |
| lambda chain | <immunology> Although light chains are found in many multimeric proteins, L chain usually refers to the light chains of immunoglobulins. These are of 22 kD and of one of two types, kappa or lambda. A single immunoglobulin has identical light chains (2 kappa or 2 lamda). Light chains have one variable and one constant region. There are isotype variants of both kappa and lamda. (25 Jun 1999) |
| lambda phage | <virology> Bacterial DNA virus, first isolated from E. Coli. Its structure is similar to that of the T even phages. Lambda genetic material consists of a double-stranded DNA molecule with 5' twelve-base-pair sticky ends, known as cos sites, which permit circularisation of the DNA molecule. It shows a lytic cycle and a lysogenic cycle and studies on the control of these alternative cycles have been very important for our understanding of the regulation of gene transcription. It is used as a cloning vector, accommodating fragments of DNA up to 15 kilobase pairs long. For larger pieces, the cosmid vector was constructed from its ends. (14 Mar 2000) |
| lambda sign | <radiology> Small ascending aorta: same size as right and left coronary aa., hypoplastic left heart syndrome (12 Dec 1998) |
| bacteriophage | <microbiology, virology> Viruses that have a specific affinity for and infect bacteria. The bacteriophages that attack Escherichia coli are termed coliphages, examples of these are lambda phage and the T even phages, T2, T4 and T6. Basically, phages consist of a protein coat or capsid enclosing the genetic material, DNA or RNA, that is injected into the bacterium upon infection. In the case of virulent phages all synthesis of host DNA, RNA and proteins ceases and the phage genome is used to direct the synthesis of phage nucleic acids and proteins using the host's transcriptional and translational apparatus. These phage components then self assemble to form new phage particles. The synthesis of a phage lysozyme leads to rupture of the bacterial cell wall releasing, typically 100-200 phage progeny. The temperate phages, such as lambda, may also show this lytic cycle when they infect a cell, but more frequently they induce lysogeny. The study of bacteriophages has been important for our understanding of gene structure and regulation. Lambda has been extensively used as a vector in recombinant DNA studies. (15 Nov 1997) |
| bacteriophage 2 depolymerase | <enzyme> Hydrolyzes glycolipoproteins and lipopolysaccharides; releases aminosugars Registry number: EC 3.2.1.- Synonym: phage 2 depolymerase (26 Jun 1999) |
| bacteriophage immunity | The state induced in a bacterium by lysogenization, the lysogenic bacterium being insusceptible to further lysogenization or to a lytic cycle by a superinfecting bacteriophage, in contradistinction to bacteriophage resistance. (05 Mar 2000) |
| bacteriophage m13 | <microbiology> A bacteriophage (a virus which infects bacteria) that has single-stranded DNA. It is used as a method of obtaining single strands of foreign DNA so that the foreign DNA can be sequenced (that is, the order of its nucleotide bases can be determined). It is also used in procedures to create mutations in vitro (in a test tube rather than within an organism). (09 Oct 1997) |
| bacteriophage mu | An unassigned species of temperate coliphage, in the family myoviridae, composed of a linear, double-stranded molecule of DNA, which is able to insert itself at random at any point on the host chromosome. It frequently causes a mutation by interrupting the continuity of the bacterial operon at the site of insertion. (12 Dec 1998) |
| bacteriophage omicron x174 | <microbiology> A bacteriophage (a virus that infects bacteria) which has as its genetic material DNA in single strands instead of the usual double strands. The virus is useful to those who study how DNA replicates. (09 Oct 1997) |
| bacteriophage p1 | An unassigned species of temperate bacteriophage in the family myoviridae which infects e. Coli. It is the largest of the coliphages and consists of double-stranded DNA, terminally redundant, and circularly permuted. (12 Dec 1998) |
| bacteriophage p2 | An unassigned species of temperate bacteriophage in the family myoviridae which infects e. Coli. It consists of linear double-stranded DNA with 19-base sticky ends. (12 Dec 1998) |