blastula An early developmental stage of vertebrate embryos formed by cleavage of the fertilized egg, in which the embryo consists of a single layer of cells surrounding a cavity(the blending inheritance A discredited model of inheritance suggesting that the characteristics of an individual result from the smooth blending of fluid like influences from its parents blunt-end ligation The ligating or attaching of blunt-ended pieces of dna by T4 DNA ligase. Used in creating hybrid vectors bottleneck a brief reduction in size of a population which usually leads to random genetic drift brachydactyly A human phenotype of unusually short digits, generally inherited as an autosomal dominant branch migration 1. The process in which a crossover point between two DNA duplexes slides along the duplexes 2. The process by which a single invading DNA strand extends its partial pairing with its complementary strand as it displaces the resident strand from a dNA duplex breakage and reunion The general mode by which recombination occurs. DNA duplexes are broken and reunited in a crosswise fashion according to the Holliday model breakage-fusion-bridge cycle Damage that happens to a dicentric chromosome during each cell cycle bridging cross A cross made to transfer alleles between two sexually isolated species by first transferring the alleles to an intermediate species that is sexually compatible with both broad heritability(H 2) The proportion of total phenotypic variance at the population level that is contributed by enetic variance bud A daughter cell formed by mitosis in yeast; one daughter cell retains the cell wall of the
blastula An early developmental stage of vertebrate embryos formed by cleavage of the fertilized egg, in which the embryo consists of a single layer of cells surrounding a cavity (the blastocoel). blending inheritance A discredited model of inheritance suggesting that the characteristics of an individual result from the smooth blending of fluid like influences from its parents. blunt-end ligation The ligating or attaching of blunt-ended pieces of DNA by T4 DNA ligase. Used in creating hybrid vectors. bottleneck A brief reduction in size of a population which usually leads to random genetic drift. brachydactyly A human phenotype of unusually short digits, generally inherited as an autosomal dominant. branch migration 1. The process in which a crossover point between two DNA duplexes slides along the duplexes. 2. The process by which a single invading DNA strand extends its partial pairing with its complementary strand as it displaces the resident strand from a DNA duplex. breakage and reunion The general mode by which recombination occurs. DNA duplexes are broken and reunited in a crosswise fashion according to the Holliday model. breakage-fusion-bridge cycle Damage that happens to a dicentric chromosome during each cell cycle. bridging cross A cross made to transfer alleles between two sexually isolated species by first transferring the alleles to an intermediate species that is sexually compatible with both. broad heritability (H^2) The proportion of total phenotypic variance at the population level that is contributed by genetic variance. bud A daughter cell formed by mitosis in yeast; one daughter cell retains the cell wall of the
parent, and the other( the bud) forms a new cell wal buoyant density A measure of the tendency of a substance to float in some other substance; large molecules are distinguished by their differing buoyant densities in some standard fluid Measured by density-gradient ultracentrifugation buoyant density of dna A measure of the density of dna determined by the equilibrium point reached by dNA after density gradient centrifugation Burkitt lymphoma translocation bringing a specific oncogene next to a novel regulatory elemen 5 A cancer of the lymphatic system manifested by tumours in the jaw, often associated with a Cytosine or cytidine callus An undifferentiated clone of plant cells cAMP(cyclic adenosine monophosphate) A molecule that plays a key role in the regulation of various processes within the cell canalized character a character whose phenotype is kept within narrow boundaries even in the presence of disturbing environments or mutations cancer A syndrome that involves the uncontrolled and abnormal division of eukaryotic cells. An formal term for a diverse class of diseases marked by abnormal cell proliferation cancer-family syndrome pedigree in which unusually large numbers of blood relatives develop certain kinds of cap A methylated guanine residue added in reverse polarity(ie 3'pMeG5'ppp5'NpNp3 )to protein and acts as an initial binding site for ribosomes during translation CAP(catabolite activator protein) A protein, which binds cyclic AMP, whose presence is necessary for the activation of operons whose activity is repressed by the presence of glucose(catabolite repression)eg
parent, and the other (the bud) forms a new cell wall. buoyant density A measure of the tendency of a substance to float in some other substance; large molecules are distinguished by their differing buoyant densities in some standard fluid. Measured by density-gradient ultracentrifugation. buoyant density of DNA A measure of the density of DNA determined by the equilibrium point reached by DNA after density gradient centrifugation. Burkitt lymphoma A cancer of the lymphatic system manifested by tumours in the jaw, often associated with a translocation bringing a specific oncogene next to a novel regulatory element. C Cytosine or cytidine. callus An undifferentiated clone of plant cells. cAMP (cyclic adenosine monophosphate) A molecule that plays a key role in the regulation of various processes within the cell. canalized character A character whose phenotype is kept within narrow boundaries even in the presence of disturbing environments or mutations. cancer A syndrome that involves the uncontrolled and abnormal division of eukaryotic cells. An informal term for a diverse class of diseases marked by abnormal cell proliferation. cancer-family syndrome pedigree in which unusually large numbers of blood relatives develop certain kinds of cancers. cap A methylated guanine residue added in reverse polarity (ie 3'pMeG5'ppp5'NpNp3') to the 5' end of eukaryotic mRNA during transcription initiation. The cap binds a cap binding protein and acts as an initial binding site for ribosomes during translation. CAP (catabolite activator protein) A protein, which binds cyclic AMP, whose presence is necessary for the activation of operons whose activity is repressed by the presence of glucose (catabolite repression) eg
lac(lactose), ara(arabinose), gal(galactose)etc. cAMP-CAP complex binds to a site, the CAP binding site, which is centred at-6l to-62 from the transcription start site in the lac d The protein shell of a virus capsomere Protein clusters making up discrete subunits of a viral protein shell carbon source A nutrient(such as sugar) that provides carbon skeletons needed for synthesis of new organic mole ecules ana carcinogen An agent(chemical or radiation) that causes cancer carcinoma tumour arising from epithelial tissue(eg glands breast; skin; linings of the urogenital carrier An individual who possesses a mutant allele but does not express it in the phenotype because of a dominant allelic partner; thus, an individual of genotype Aa is a carrier of a if there cassette mechanism The mechanism by which homothallic yeast cells al ternate mating types, involves two sons(cassettes) and a region where these cassettes can be expressed ( cassette player) cassette model A model to explain mating-type switching in yeast. Information for both a and alpha mating types is assumed to be present as silent cassettes; a copy of either type of cassette may be transposed to the mating-type locus, where it is played(transcribed) catabolite activator protein(CAP A protein that when bound with cyclic AMP can attach to sites on sugar-metabolizing operons to enhance transcription of these operons catabolite repression Repression(inactivation) of certain sugar-metabolizing operons(eg lac) in favour of glucose utilization when glucose is the predominant carbon source in the environment of he cell
lac (lactose), ara (arabinose), gal (galactose) etc. cAMP-CAP complex binds to a site, the CAP binding site, which is centred at -61 to -62 from the transcription start site in the lac operon promoter. capsid The protein shell of a virus. capsomere Protein clusters making up discrete subunits of a viral protein shell. carbon source A nutrient (such as sugar) that provides carbon skeletons needed for synthesis of new organic molecules (anabolism). carcinogen An agent (chemical or radiation) that causes cancer. carcinoma tumour arising from epithelial tissue (eg glands; breast; skin; linings of the urogenital, intestinal and respiratory systems). carrier An individual who possesses a mutant allele but does not express it in the phenotype because of a dominant allelic partner; thus, an individual of genotype Aa is a carrier of a, if there is complete dominance of A over a. cassette mechanism The mechanism by which homothallic yeast cells alternate mating types, involves two silent transposons (cassettes) and a region where these cassettes can be expressed (cassette player). cassette model A model to explain mating-type switching in yeast. Information for both a and alpha mating types is assumed to be present as silent cassettes ; a copy of either type of cassette may be transposed to the mating-type locus, where it is played (transcribed). catabolite activator protein (CAP) A protein that when bound with cyclic AMP can attach to sites on sugar-metabolizing operons to enhance transcription of these operons. catabolite repression Repression (inactivation) of certain sugar-metabolizing operons (eg lac) in favour of glucose utilization when glucose is the predominant carbon source in the environment of the cell
catalyst A substance that increases the rate of a chemical reaction without itself being permanently cation A positively charged ion(such as K+, Na+, NH4 +) CCAAt box An invariant DNA sequence at about minus 70 base pairs from the origin of transcription in many eukaryotic promoters CDNA See complementary dNA CDNAlibrary A pool of complementary dNA clones produced by cDNA cloning of total messenger RNA from a single source(cell type, tissue, embryo cell autonomous A genetic trait in multicellular organisms in which only genotypically mutant cells exhibit the mutant phenotype. Conversely, a nonautonomous trait is one in which genotypically mutant cells cause other cells (regardless of their genotype) to exhibit a mutant genotype cell cycle The cycle of cell growth, replication of the genetic material and nuclear and cytoplasmic cell division The process by which two cells are formed from one. See meiosis and mitosis cell fate The ultimate differentiated state to which a cell has become committed cell lineage A pedigree of cells related through asexual division cell-free system A mixture of cytoplasmic and/or nuclear components from cells and used for in vitro protein synthesis or transcription or DNA replication or other purposes cellular blastoderm The stage of the blastoderm, initially a syncytium, in insects after the nuclei have each
catalyst A substance that increases the rate of a chemical reaction without itself being permanently changed. cation A positively charged ion (such as K^+, Na^+, NH4^+). CCAAT box An invariant DNA sequence at about minus 70 base pairs from the origin of transcription in many eukaryotic promoters. cDNA See complementary DNA. cDNA library A pool of complementary DNA clones produced by cDNA cloning of total messenger RNA from a single source (cell type, tissue, embryo). cell autonomous A genetic trait in multicellular organisms in which only genotypically mutant cells exhibit the mutant phenotype. Conversely, a nonautonomous trait is one in which genotypically mutant cells cause other cells (regardless of their genotype) to exhibit a mutant phenotype. cell cycle The cycle of cell growth, replication of the genetic material and nuclear and cytoplasmic division. cell division The process by which two cells are formed from one. See meiosis and mitosis cell fate The ultimate differentiated state to which a cell has become committed. cell lineage A pedigree of cells related through asexual division. cell-free system A mixture of cytoplasmic and/or nuclear components from cells and used for in vitro protein synthesis or transcription or DNA replication or other purposes. cellular blastoderm The stage of the blastoderm, initially a syncytium, in insects after the nuclei have each
been separately packaged into a cell membrane centimorgan(cm A chromosome mapping unit. One centimorgan equals 1% recombinant offspring central dogma The original postulate that genetic information can be transferred only from nucleic acid to nucleic acid and from nucleic acid to protein, that is from dna to DNA from dNA to RNA and from RNa to protein(although information transfer from RNa to DNA was not excluded and is now known to occur [reverse transcription)). Transfer of genetic nformation from protein to nucleic acid never occurs centric fragment a piece of chromosome containing a centromere centriole A short cylindrical organelle, found in pairs arranged at right angles to each other at the centre of a microtubule organizing centre(MToC)or centrosome, found in eukaryotes (except in higher plants). A centriole is similar in structure to the basal body found at the base of eukaryotic cilia and flagella and organises the axoneme, the bundle of microtubules and other proteins forming the core of each cilium or flagellum. The centrosome organizes formation of a spindle during mitosis or meiosis centromere A kinetochore; the constricted region of a nuclear chromosome, to which the spindle fibres attach during division centromere marker locus located close to a centromere centromeric fission Creation of two chromosomes from one by splitting the centromere centrosome The primary microtubule organising center(MTOC) of animal cells, that divides prior to cell division each daughter MTOC acts as one pole of the spindle apparatus. The centrosome usually contains a pair of centrioles chaperone See molecular chaperone character An attribute of individuals within a species for which heritable differences can be defined character difference
been separately packaged into a cell membrane. centimorgan (cm) A chromosome mapping unit. One centimorgan equals 1% recombinant offspring. central dogma The original postulate that genetic information can be transferred only from nucleic acid to nucleic acid and from nucleic acid to protein, that is from DNA to DNA from DNA to RNA and from RNA to protein (although information transfer from RNA to DNA was not excluded and is now known to occur [reverse transcription]). Transfer of genetic information from protein to nucleic acid never occurs. centric fragment A piece of chromosome containing a centromere. centriole A short cylindrical organelle, found in pairs arranged at right angles to each other at the centre of a microtubule organizing centre (MTOC) or centrosome, found in eukaryotes (except in higher plants). A centriole is similar in structure to the basal body found at the base of eukaryotic cilia and flagella and organises the axoneme, the bundle of microtubules and other proteins forming the core of each cilium or flagellum. The centrosome organizes formation of a spindle during mitosis or meiosis. centromere A kinetochore; the constricted region of a nuclear chromosome, to which the spindle fibres attach during division. centromere marker locus located close to a centromere. centromeric fission Creation of two chromosomes from one by splitting the centromere. centrosome The primary microtubule organising center (MTOC) of animal cells, that divides prior to cell division each daughter MTOC acts as one pole of the spindle apparatus. The centrosome usually contains a pair of centrioles. chaperone See molecular chaperone. character An attribute of individuals within a species for which heritable differences can be defined. character difference