 Intro To Plant Genetics Definitions
Info provided by: Greg Green's Cannabis Breeder's Bible
Genes - Genes are the units of heredity transmitted from parent to offspring, usually as part of a chromosone. Genes usually control or determine a single characteristic in the offspring. There are genes responsible for each feature of your plant. Including leaf color, stem structure, smell, potency etc.
Gene Pairs - All life is mad up of a pattern of genes. Similar to the two sides to a zipper. One side (gene) is inhereted from the mother and the other side (gene) is inherited from the father. Each gene occupies a specific locus on the chain (zipper) and controls information about the eventual characteristic of the plant. Each gene locus contains two genes, one from each parent.
These gene pairs are denoted by a pair of letters (ex. BB, Bb, bb).
Any letter can be applied to any gene pair. "B" can represent "Big Buds" while "b" can represent "small buds" in this instance.
Chromosone - A thread like structure of nucleic acids and proteins in the cell nuclei of higher organisms that carries a set of linked genes, usuall paired.
Locus or loci - A position on a chromosone where a particular gene pair is located.
Allele - Allels are any number of alternative forms of one gene. For ex. the gene for purple bud color may have two forms, or alleles, one for purple and another for dark red.
Homozygous - Having identical alleles at one or more genetic loci, which is not a heterozygote and breeds true. Your plant is said to be homozygous for one feature when it carries the same gene twice in the responsible gene pair, which means both genes of the gene pair are identical (ex. BB)
Heterozygous - Having different alleles at one or more genetic loci. Your plant is said to be heterozygous for one feature when the genes of the responsible gene pair is unequal or dissimilar (ex. Bb)
Phenotype - The summary of all features you can detect or recognize from the outside of your plant. Ex. Color, smell, taste etc.
Genotype - The genetic constitution of your plant as distinguished from the phenotype. The genotype charachterizes how your plant looks from the inside. It is the summary of all genetic information that your plant carries and passes on to its offspring.
Dominant - Dominant is used to describe a gene or allele that is expressed even when inherited from only one parent. It is also used to describe a hereditary trait controlled by a gene and appearing in an individual to the exclusion of its counterpart, when allels for both are present. Only one dominant allele in the gen pair must be present to become the expressed genotype and eventually the expressed phenotype of your plant.
Recessive - Recessive describes a gene, allele or hereditary trait expressed only in homozygotes, being masked in heterozygotes by a dominant allele or trait. A gene is called recessive when its effect can not be seen in the phenotype of your plant when only one allele is present. The same allele must be present twice in the gene pair in order for you to see it expressed in the phenotype of your plant if it's a recessive trait.
Dominant/Recessive genetic notation - Assume that the dominant "B" allele carries the hereditary trait for Big Bud. While the recessive "b" allele carries the hereditary trait for small bud. Since "B" is dominant, a plant with the Bb genotype will always produce Big Bud. The "B" is dominant over the "b". In order for a recessive gene to be displayed in the phenotype, both genes in the gene pair must be recessive. So a plant with "BB or Bb gene will always produce Big Bud. Only a plant with "bb" genes will produce small bud.
Last edited by BloodShotI'z; 11-14-2007 at 12:41 AM.
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