1.1 Terms used in Genetics

Alleles Alleles are the pair of genes controlling a pair of Contrasting characters.

Multiple Alleles: If a gene undergoes mutation . it can exist more than two or more forms are called Multiple Alleles.


[Information gathered from various sources on Internet, purely for Learning purpose]

Phenotype: (Tall x Dwarf)

It is the total external expressions or Appearence of an rganism for a Particular character. Irrespective of its Geneotype.

PHENOTYPE and GENOTYPE Source: https://www.gsiccharter.com/cms/lib/GA01933819/Centricity/Domain/209/Ch%205%20Genetics%20notes.pdf

Genotype: (TT x tt)

It is the Genetic constitution of an organism for a Particular Character. or Which is responsible for Phenotypic Expression.

[GENOTYPE] Image Source: WIkipedia

Homozygous Condition- (Tallness TT) Organism having two simillar genes for a Particular Character on Homologous Chromosomes.

Heterozygous Condition(Tallness Tt) Organism having two Dissimilar genes for a Particular Character on Homologous Chromosomes.

Dominant Gene The Gene which expresses its Character in the Hybrid is called Dominant Gene.

Recessive Gene: The Gene which fails to express its Character in the Hybrid is called Recessive Gene.

PureLine: The individual with homozygous traits obtained due to continues self breeding over 3 to 4 Generations.

Hybrid: It is an offspring obtained when a cross between the 2 Parents which are differ in one or two Character.

Monohybrid: It is a cross between two parents which differ in one Character.

Dihybrid: it is a cross between two parents which differ in two characters.

Checkerboard or Punnet Square: it is a schematic table used to determin the various combinations of Genotype and Phenotypes of offsprings in a cross. The Genotypes of F1 and F2 are Schematically represented is called Checkerboard.

Punnet Square Image Source Wiki

Allelomorphs: The Genes controlling Height in Pea plants has two Contrasting forms.Namely , Genes for Tallness T and Genes for Dwarfness t , these two genes constitute the Alleles and Occupy the Same Locus on the Homologous Chromosomes.


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