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| Lag phase |
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The initial growth phase, during which cell number remains relatively constant prior to rapid growth. See growth phase.
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| Lawn |
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A uniform and uninterrupted laver of bacterial growth, in which individual colonies cannot be observed.
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| Legume |
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A member of the pea family that possesses root nodules containing nitrogen-fixing bacteria.
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| Library |
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A collection of cells, usually bacteria or yeast, that have been transformed with recombinant vectors carrying DNA inserts from a single species. (See cDNA library, Expression library, Genomic library.)
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| Ligase (DNA ligase). |
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An enzyme that catalyzes a condensation reaction that links two DNA molecules via the formation of a phosphodiester bond between the 3' hydroxyl and 5' phosphate of adjacent nucleotides.
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| Ligate |
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The process of joining two or more DNA fragments.
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| Lineage |
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A chart that traces the flow of genetic information from generation to generation.
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| Linkage |
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The frequency of coinheritance of a pair of genes and/or genetic markers, which provides a measure of their physical proximity to one another on a chromosome.
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| Linkage map |
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See Genetic linkage map.
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| Linked genes/markers |
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Genes and/or markers that are so closely associated on the chromosome that they are coinherited in 80% or more of cases.
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| Linker. |
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A short, double-stranded oligonucleotide containing a restriction endonuclease recognition site, which is ligated to the ends of a DNA fragment.
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| Liposomes |
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Membrane-bound vesicles constructed in the laboratory to transport biological molecules.
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| Locus (plural = loci). |
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A specific location or site on a chromosome.
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| Log phase |
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See Logarithmic phase.
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| Logarithmic phase (log or |
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The steepest slope of the growth curve--the phase of vigorous growth during which cell number doubles every 20-30 minutes. (See Growth phase.)
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| Lysis |
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The destruction of the cell membrane.
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| Lysogen |
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A bacterial cell whose chromosome contains in- tegrated viral DNA.
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| Lysogenic |
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A type or phase of the virus life cycle during which the virus integrates into the host chromosome of the infected cell, often remaining essentially dormant for some period of time. See Lysogen.
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| Lytic |
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A phase of the virus life cycle during which the vi- rus replicates within the host cell, releasing a new generation of viruses when the infected cell lyses.
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