PRINCIPLES OF INHERITANCE AND VARIATION(OVERVIEW PTS PART1)
Genetics-Study of genes
Heredity-The tendency of offsprings to the resemble their parents.
Variation-The tendency of the offspring to differ from their parents.
Inheritance-The process by which characters are passed on from a parent to progeny.
Hybrids-Offspring obtained from a cross between two genetically different organisms.
Monohybrid cross-A cross involving two forms of a single character.
Monohybrid phenotypic ratio-3:1
Monohybrid genotypic ratio-1:2:1
Factor-A physical body which determines a character.
Gene-Unit of inheritance.
Alleles-The various forms of a gene.
Dominant gene-The gene that is expressed in heterozygous condition.
Recessive gene-The gene that is suppressed in heterozygous condition.
(Homozygous-The occurrence of same kind of gene for a character.
Heterozygous-The occurrence of two different kinds of genes for a character.)
Phenotype-The physical appearance of an organism.(observable characters)
Genotype-The genetic constitution of an organism.
Punnett Square-The visual diagram of the crossing of organisms.
Law of dominance-When two contrasting factors for a character are found together one dominates over the other.
Law of segregation-Before the formation of gametes the two factors for a character present in an individual will separate or segregate from each other.
Law of purity of gametes
Law of independent assortment-When two pairs of traits are combined in a hybrid,segregation of one pair of characters is independent of the other pair of characters.
Dihybrid cross-A cross involving two characters.
Dihybrid phenotypic ratio-9:3:3:1
Dihybrid genotypic ratio-1:2:1:2:4:2:1:2:1
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PRINCIPLES OF INHERITANCE PART ONE