clips
human bean
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Glossary
allele - An alternative form of a gene, located on corresponding loci of homologous chromosomes. They have different effects on the same trait or development processes and can mutate, one to the other.
They may affect the phenotype quantitatively or qualitatively. >Note: In a population, many different alleles may reside at a particular locus; in a single diploid plant though, a maximum of 2 different alleles are possible at any one locus.
allele frequency ( gene frequency) - The frequency of the occurrence of a particular allele in relation to the frequency of all the alleles at that locus in a given population.
allozyme - enzymes differing in electrophoretic mobility (i.e., which migrate different distances through the substrate when an electrophoresis test is performed) as a result of allelic differences in a single gene; allozyme variation thus indicates genetic variation. One of the oldest lab tests for genetic analysis.
autochthonous - "sprung from the earth," native to a particular region from a very early time. The Siberian sled dog is an autochthonous dog in Siberia. (Pronounced "aw-TOC-thun-us.")
autosome - A typical chromosome rather than a sex chromosome.
10.breeding: The propagation and genetic manipulation by hybridization or deliberate self-crossing of plants, for the purpose of selecting improved offspring.
breeding value - The value of an individual as defined by the mean value of its progeny. It is equal to the sum of the average effects of the genes it carries, derived from the sum of the effects of pairs of alleles at each locus and over all loci.
chromosomes - structures within the nuclei of living cells which are made up of nucleotide sequences, the biochemical information carriers which we call genes. All genes exist as tiny portions of chromosomes; although we may speak of particular genes individually, in isolation, they do not exist as separate entities, but are always found as subunits of chromosomes.
codominance (partial dominance, or incomplete dominance) - A type of gene action, which results in the heterozygote showing the phenotypic effects of both alleles. >Note: Its a basic genetic premise that any two alleles at a locus may show from 'complete dominance' through to 'no dominance'.(codominance)
correlated response - A change in one character(phenotype) occurring as an incidental consequence of selection for a seemingly independent character, i.e. where different traits are controlled by the same gene(s) or conditions, e.g. the various responses to low temperatures on different traits, would be correlated.
crossing over - The mutual exchange of corresponding segments between chromatids of homologous chromosomes, during meiotic prophase, which results in the recombination of linked genes.
cytoplasm - All the material between the nuclear membrane and the cell wall. i.e. the protoplasm excluding the nucleus. > Note: inheritance of cytoplasmic genes is yet to be explored by DC breeders, and may hold much valuable information related to pest and pathogen resistance, sex linkage, adaptation.
deleterious · harmful or injurious.
diploid - the body cells of most complex animal organisms such as birds and mammals all have their chromosomes in pairs derived from sexual reproduction, such that one chromosome of a pair comes from the father, the other from the mother. The sex cells from only one parent have only half the number of chromosomes of cells in other parts of the body: the normal chromosome number is known as the diploid number, the chromosome number of sperm and egg cells is called the haploid number.
disequilibrium - imbalance or instability.
dominant - said of an allele which by itself alone will produce a particular phenotype regardless of which other allele may be present on the other matching chromosome of the diploid pair; thus it takes only one copy of the chromosome to cause a dominant trait to be expressed in the phenotype.
electrophoresis - one of the most useful lab techniques for revealing genetic variation. which came into widespread use in the 1960s. It involves placing sample material (blood, e.g.) on a gel substrate. An electrical field is then applied between the two ends of the substrate, causing protein molecules to migrate through the gel. Proteins with different ionic charge will travel different distances across the substrate. Staining subsequently makes bands of protein in the substrate visible, so that various samples can be "read" in much the same manner as a supermarket bar coded label.
elite germplasm - Germplasm that has been manipulated for use in a breeding program, such as advanced-, inbred-, or pure lines.
endosperm - Triploid tissue which develops from the fusion of a sperm nucleus with the two polar nuclei of the embryo sac.
epistasis - Interallelic interactions between two or more loci that control the expression of a character.
expression - not all genes possessed by an organism will result in detectable physical traits or differences in that organism; the genes that do are expressed. Dominant genes are always expressed, but recessive genes may be present for many generations without physical expression in the phenotype.
fecundity - the number of progeny produced by animals when reproducing.
fertility - the relative degree of reproductive success, i.e. the frequency with which mating is followed by pregnancy.
fitness, Darwinian fitness: The relative probability of survival and reproduction of a genotype or species.
gametes - the sex cells of sexually reproducing organisms, i.e. spermatozoa and ova.
genetic diversity - The range of a genepool; the amount of genetic variation present in a population or species as a consequence of its evolutionary pathways. >Note: Improved genetic combinations depend on genetic diversity. A population with only slight variation can only be slightly improved. Outcrosses are made to increase genetic diversity in a line, cultivar or population.
genetic drift - Deviation from the population mean due to the limited size of a sample. The random fluctuation of gene frequencies in a population from generation to generation due to significant chance factors rather than natural selection. It is most apparent in small, isolated populations.
genome - the total genetic information possessed by an individual, a breed or a species.
genotype - the invisible genetic makeup of an individual organism, which includes alleles which may be recessive and therefore have no visible physical expression.
half-sib: Progeny with only one common parent.>Note: full-sibs are individuals that have both parents in common.
heritability - The capacity of a character to be inherited; the proportion of the phenotypic variance which is due to genetic effects; h^2.
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heterosis, hybrid vigor: The increase with respect to one or more of size, yield and performance, found in some heterozygous genotypes by comparison with either homozygous parent.
heterotypic - displaying different types. A breed which has more than one distinct and recognizable set of "type" characteristics is heterotypic.
heterozygote - an organism that possesses different alleles at a given gene locus.
heterozygous - possessing different alleles at a given gene locus.
holistic - relating to or focussing on the entirety of a thing or an organism and the interrelationship of its component parts, instead of emphasizing different aspects or parts in isolation without considering their interactions.
homozygote - an organism that possesses identical alleles at a given gene locus.
homozygous - Having identical alleles at corresponding loci on homologous chromosomes. i.e. AA, aa, A1A1, or A2A2. > Note: The term "fixed" refers to a locus that is homozygous in an entire population
hybrid: The progeny of genetically dissimilar parents; a heterozygote
inbred line (IBL) - A line produced by at least five generations of sequential inbreeding, self fertilization or backcrossing accompanied by selection within and between lines so that the individuals are considered to be homozygous, or nearly so.
inbreeding coefficient - a number used to quantify the probability that an organism will have identical alleles from the same ancestral source, usually computed by analyzing the pedigree for "loops" in which the same ancestor is found on both the male and female sides of a mating.
lethal - likely to cause or capable of causing the death of an organism. A lethal gene is one which could either cause an aborted fetus or the death of the organism at some later stage of its life.
landrace - An early cultivated form of a crop species, evolved from a wild population.
locus (pl. loci) - the physical location of a given gene on a particular chromosome.
maternal inheritance, matrillinear inheritance - certain traits controlled by genetic factors in the cytoplasm and transmitted to the offspring only from the seed parent.
meiosis - the kind of cell division which produces spermatozoa and ova or gametes and which reduces the chromosome number to half the normal complement.
microsatellite - a kind of DNA testing which detects short DNA sequence variations at particular highly variable sites; used in so-called "DNA fingerprinting."
mutation - A sudden variation in the hereditary material of a cell, due to changes in either gene(s) or chromosome(s).
phenotypic - The observable(structural and functional) characters of an organism due to the interaction between genotype and environment. >Note: the phenotype does not always represent the genotype. There are numerous reasons for this including epistasis, dominance, and polygenes.
plasticity, plastic response: Morphological and physiological changes, in the expression of an individual’s genotype, caused by environmental factors.
pleiotropy, pleiotropic effect:The effect of an allele or gene that affects several traits at the same time.
polymorphism - difference or variation in form, diversity. Molecular geneticists study protein polymorphism, different forms of proteins in an organism indicating different alleles. Polymorphism studies show that from 20 to 50 percent of gene loci in most species have two or more allele forms. recessive - a gene which contributes to the phenotype only if it is present in homozygous form. It takes two identical copies of a recessive gene to produce the trait it governs in the phenotype. In practice many genes are neither clearly dominant nor recessive, in which case geneticists speak of variable expressivity or incomplete penetrance.
polyploid - An organism with more than 2 sets of chromosomes in its body cells. >Note: Seek to understand these associated terms: allopolyploid,autopolyploid,aneuploid,tetraploid,t riploid,diploid,haploid.
quantitative variation - This term is loosely synonymous with continuous variation - continuous variation caused by polygenes. >Note: Most of the traits of focus in the drug cultivar genepoool are quantitative. Seek to understand the difference between qualitative and quantitative variation/characters.
RFLP - "restriction fragment length polymorphism" -- a DNA analysis technique which involves the use of enzymes to break the DNA chain at specific nucleotide sequences: the resulting "restriction fragments" are then analyzed by the use of electrophoresis and blotting techniques. RFLPs are used as markers for known genetic traits and can be employed for genome mapping.
recurrent parent - The name of the parent to which a hybrid is crossed in a backcross.
selection - Any process, natural or artificial, which permits an increase in the proportion of certain genotypes or groups of genotypes in succeeding generations, usually at the expense of other genotypes.
stigma - The portion of the pistil which receives pollen in pollination.
sublethal - having known deleterious effects which by themselves will not usually cause the death of the organism but which handicap it in some way. Several sublethal genes may nevertheless combine to form a "lethal equivalent."
subvital - having known effects which work to reduce the overall vitality and health ofthe organism.
typology - the study of types or groups of distinguishing characteristics. Typological thinking involves emphasis on visible superficial characteristics, often mere cosmetic traits which have little to do with the health and viability of the animal possessing them.
variance(V), sample variance (s^2): The sum of the squared deviations about the MEAN. >Note: the sum of the squared deviations is divided by “n” for variance, and divided by “n-1” for Sample variance.)
The square root of variance is known as standard deviation.
viability - the relative survivorship of the fertilized ova resulting from a reproductive event. Nonviability may involve ova which simply fail to develop, fetuses which abort, nestlings which die or juveniles which fail to survive to maturity.
xenia - A phenotypically evident effect of the pollen genotype on the character of the endosperm or embryo. >Note: Although xenia is NOT phenotypically evident when expressed within a thick opaque seedcoat, (as with cannabis), exploring xenia for educational purposes will lead you to much data about pollen, pollination, and endosperm.
*nearly all the definitions are taken directly from Elsevier’s Dictionary of Plant Genetic Resources. 1991 ISBN0444889590
Glossary
allele - An alternative form of a gene, located on corresponding loci of homologous chromosomes. They have different effects on the same trait or development processes and can mutate, one to the other.
They may affect the phenotype quantitatively or qualitatively. >Note: In a population, many different alleles may reside at a particular locus; in a single diploid plant though, a maximum of 2 different alleles are possible at any one locus.
allele frequency ( gene frequency) - The frequency of the occurrence of a particular allele in relation to the frequency of all the alleles at that locus in a given population.
allozyme - enzymes differing in electrophoretic mobility (i.e., which migrate different distances through the substrate when an electrophoresis test is performed) as a result of allelic differences in a single gene; allozyme variation thus indicates genetic variation. One of the oldest lab tests for genetic analysis.
autochthonous - "sprung from the earth," native to a particular region from a very early time. The Siberian sled dog is an autochthonous dog in Siberia. (Pronounced "aw-TOC-thun-us.")
autosome - A typical chromosome rather than a sex chromosome.
10.breeding: The propagation and genetic manipulation by hybridization or deliberate self-crossing of plants, for the purpose of selecting improved offspring.
breeding value - The value of an individual as defined by the mean value of its progeny. It is equal to the sum of the average effects of the genes it carries, derived from the sum of the effects of pairs of alleles at each locus and over all loci.
chromosomes - structures within the nuclei of living cells which are made up of nucleotide sequences, the biochemical information carriers which we call genes. All genes exist as tiny portions of chromosomes; although we may speak of particular genes individually, in isolation, they do not exist as separate entities, but are always found as subunits of chromosomes.
codominance (partial dominance, or incomplete dominance) - A type of gene action, which results in the heterozygote showing the phenotypic effects of both alleles. >Note: Its a basic genetic premise that any two alleles at a locus may show from 'complete dominance' through to 'no dominance'.(codominance)
correlated response - A change in one character(phenotype) occurring as an incidental consequence of selection for a seemingly independent character, i.e. where different traits are controlled by the same gene(s) or conditions, e.g. the various responses to low temperatures on different traits, would be correlated.
crossing over - The mutual exchange of corresponding segments between chromatids of homologous chromosomes, during meiotic prophase, which results in the recombination of linked genes.
cytoplasm - All the material between the nuclear membrane and the cell wall. i.e. the protoplasm excluding the nucleus. > Note: inheritance of cytoplasmic genes is yet to be explored by DC breeders, and may hold much valuable information related to pest and pathogen resistance, sex linkage, adaptation.
deleterious · harmful or injurious.
diploid - the body cells of most complex animal organisms such as birds and mammals all have their chromosomes in pairs derived from sexual reproduction, such that one chromosome of a pair comes from the father, the other from the mother. The sex cells from only one parent have only half the number of chromosomes of cells in other parts of the body: the normal chromosome number is known as the diploid number, the chromosome number of sperm and egg cells is called the haploid number.
disequilibrium - imbalance or instability.
dominant - said of an allele which by itself alone will produce a particular phenotype regardless of which other allele may be present on the other matching chromosome of the diploid pair; thus it takes only one copy of the chromosome to cause a dominant trait to be expressed in the phenotype.
electrophoresis - one of the most useful lab techniques for revealing genetic variation. which came into widespread use in the 1960s. It involves placing sample material (blood, e.g.) on a gel substrate. An electrical field is then applied between the two ends of the substrate, causing protein molecules to migrate through the gel. Proteins with different ionic charge will travel different distances across the substrate. Staining subsequently makes bands of protein in the substrate visible, so that various samples can be "read" in much the same manner as a supermarket bar coded label.
elite germplasm - Germplasm that has been manipulated for use in a breeding program, such as advanced-, inbred-, or pure lines.
endosperm - Triploid tissue which develops from the fusion of a sperm nucleus with the two polar nuclei of the embryo sac.
epistasis - Interallelic interactions between two or more loci that control the expression of a character.
expression - not all genes possessed by an organism will result in detectable physical traits or differences in that organism; the genes that do are expressed. Dominant genes are always expressed, but recessive genes may be present for many generations without physical expression in the phenotype.
fecundity - the number of progeny produced by animals when reproducing.
fertility - the relative degree of reproductive success, i.e. the frequency with which mating is followed by pregnancy.
fitness, Darwinian fitness: The relative probability of survival and reproduction of a genotype or species.
gametes - the sex cells of sexually reproducing organisms, i.e. spermatozoa and ova.
genetic diversity - The range of a genepool; the amount of genetic variation present in a population or species as a consequence of its evolutionary pathways. >Note: Improved genetic combinations depend on genetic diversity. A population with only slight variation can only be slightly improved. Outcrosses are made to increase genetic diversity in a line, cultivar or population.
genetic drift - Deviation from the population mean due to the limited size of a sample. The random fluctuation of gene frequencies in a population from generation to generation due to significant chance factors rather than natural selection. It is most apparent in small, isolated populations.
genome - the total genetic information possessed by an individual, a breed or a species.
genotype - the invisible genetic makeup of an individual organism, which includes alleles which may be recessive and therefore have no visible physical expression.
half-sib: Progeny with only one common parent.>Note: full-sibs are individuals that have both parents in common.
heritability - The capacity of a character to be inherited; the proportion of the phenotypic variance which is due to genetic effects; h^2.
--------------------------------------------------------------------------------
heterosis, hybrid vigor: The increase with respect to one or more of size, yield and performance, found in some heterozygous genotypes by comparison with either homozygous parent.
heterotypic - displaying different types. A breed which has more than one distinct and recognizable set of "type" characteristics is heterotypic.
heterozygote - an organism that possesses different alleles at a given gene locus.
heterozygous - possessing different alleles at a given gene locus.
holistic - relating to or focussing on the entirety of a thing or an organism and the interrelationship of its component parts, instead of emphasizing different aspects or parts in isolation without considering their interactions.
homozygote - an organism that possesses identical alleles at a given gene locus.
homozygous - Having identical alleles at corresponding loci on homologous chromosomes. i.e. AA, aa, A1A1, or A2A2. > Note: The term "fixed" refers to a locus that is homozygous in an entire population
hybrid: The progeny of genetically dissimilar parents; a heterozygote
inbred line (IBL) - A line produced by at least five generations of sequential inbreeding, self fertilization or backcrossing accompanied by selection within and between lines so that the individuals are considered to be homozygous, or nearly so.
inbreeding coefficient - a number used to quantify the probability that an organism will have identical alleles from the same ancestral source, usually computed by analyzing the pedigree for "loops" in which the same ancestor is found on both the male and female sides of a mating.
lethal - likely to cause or capable of causing the death of an organism. A lethal gene is one which could either cause an aborted fetus or the death of the organism at some later stage of its life.
landrace - An early cultivated form of a crop species, evolved from a wild population.
locus (pl. loci) - the physical location of a given gene on a particular chromosome.
maternal inheritance, matrillinear inheritance - certain traits controlled by genetic factors in the cytoplasm and transmitted to the offspring only from the seed parent.
meiosis - the kind of cell division which produces spermatozoa and ova or gametes and which reduces the chromosome number to half the normal complement.
microsatellite - a kind of DNA testing which detects short DNA sequence variations at particular highly variable sites; used in so-called "DNA fingerprinting."
mutation - A sudden variation in the hereditary material of a cell, due to changes in either gene(s) or chromosome(s).
phenotypic - The observable(structural and functional) characters of an organism due to the interaction between genotype and environment. >Note: the phenotype does not always represent the genotype. There are numerous reasons for this including epistasis, dominance, and polygenes.
plasticity, plastic response: Morphological and physiological changes, in the expression of an individual’s genotype, caused by environmental factors.
pleiotropy, pleiotropic effect:The effect of an allele or gene that affects several traits at the same time.
polymorphism - difference or variation in form, diversity. Molecular geneticists study protein polymorphism, different forms of proteins in an organism indicating different alleles. Polymorphism studies show that from 20 to 50 percent of gene loci in most species have two or more allele forms. recessive - a gene which contributes to the phenotype only if it is present in homozygous form. It takes two identical copies of a recessive gene to produce the trait it governs in the phenotype. In practice many genes are neither clearly dominant nor recessive, in which case geneticists speak of variable expressivity or incomplete penetrance.
polyploid - An organism with more than 2 sets of chromosomes in its body cells. >Note: Seek to understand these associated terms: allopolyploid,autopolyploid,aneuploid,tetraploid,t riploid,diploid,haploid.
quantitative variation - This term is loosely synonymous with continuous variation - continuous variation caused by polygenes. >Note: Most of the traits of focus in the drug cultivar genepoool are quantitative. Seek to understand the difference between qualitative and quantitative variation/characters.
RFLP - "restriction fragment length polymorphism" -- a DNA analysis technique which involves the use of enzymes to break the DNA chain at specific nucleotide sequences: the resulting "restriction fragments" are then analyzed by the use of electrophoresis and blotting techniques. RFLPs are used as markers for known genetic traits and can be employed for genome mapping.
recurrent parent - The name of the parent to which a hybrid is crossed in a backcross.
selection - Any process, natural or artificial, which permits an increase in the proportion of certain genotypes or groups of genotypes in succeeding generations, usually at the expense of other genotypes.
stigma - The portion of the pistil which receives pollen in pollination.
sublethal - having known deleterious effects which by themselves will not usually cause the death of the organism but which handicap it in some way. Several sublethal genes may nevertheless combine to form a "lethal equivalent."
subvital - having known effects which work to reduce the overall vitality and health ofthe organism.
typology - the study of types or groups of distinguishing characteristics. Typological thinking involves emphasis on visible superficial characteristics, often mere cosmetic traits which have little to do with the health and viability of the animal possessing them.
variance(V), sample variance (s^2): The sum of the squared deviations about the MEAN. >Note: the sum of the squared deviations is divided by “n” for variance, and divided by “n-1” for Sample variance.)
The square root of variance is known as standard deviation.
viability - the relative survivorship of the fertilized ova resulting from a reproductive event. Nonviability may involve ova which simply fail to develop, fetuses which abort, nestlings which die or juveniles which fail to survive to maturity.
xenia - A phenotypically evident effect of the pollen genotype on the character of the endosperm or embryo. >Note: Although xenia is NOT phenotypically evident when expressed within a thick opaque seedcoat, (as with cannabis), exploring xenia for educational purposes will lead you to much data about pollen, pollination, and endosperm.
*nearly all the definitions are taken directly from Elsevier’s Dictionary of Plant Genetic Resources. 1991 ISBN0444889590