Multiple Allelism

Multiple allelism occurs when a single gene has more than two allelic forms.

Alleles are different versions of a gene.

Examples include the ABO blood group system with A, B, and O alleles.

Multiple allelism contributes to genetic diversity and is important in genetic testing.

ABO Blood Group System

ABO blood group system has three main alleles: A, B, and O.

Alleles determine blood types (A, B, AB, O).

A and B alleles are codominant, O allele is recessive.

Knowledge of blood type is crucial for medical practices like transfusions and organ transplants.

Coat Color in Rabbits

Rabbit coat color is influenced by multiple genes.

Genes include Agouti (A), Extension (E), and Color (C) loci.

Genes control pigmentation, distribution, and intensity.

Inheritance follows Mendelian principles, resulting in diverse coat colors.

Chromosome Theory of Heredity

Genes are located on chromosomes.

Chromosomes carry genetic information.

Mendel’s laws were integrated with chromosome theory.

Gene loci, homologous chromosomes, segregation, and independent assortment are key concepts.

Drosophila melanogaster

Fruit flies (Drosophila) are model organisms in genetics.

Short generation time, easy breeding, and visible traits.

Contributions include confirming Mendel’s laws and discovering sex-linked inheritance.

Genetic recombination, map units, and linkage mapping were studied.

Linkage, Crossing Over, Gene Linkage, Polyploidy

Linkage occurs when genes are inherited together due to proximity on the same chromosome.

Crossing over during meiosis breaks linkage.

Polyploidy involves extra chromosome sets.

Unlinked genes assort independently during meiosis.

Complete linkage is rare due to crossing over.

Linkage groups reflect genes on the same chromosome.

Morgan’s Experiment with Drosophila

Morgan studied Drosophila (fruit flies) for genetics.

Discovered sex-linked inheritance (gene for eye color on X chromosome).

Observed genetic recombination and crossing over.

Confirmed Mendel’s laws and contributed to modern genetics.

Linkage in Sweet Pea

Genes in sweet pea can be linked on the same chromosome.

Genetic recombination and crossing over can break linkage.

Map units measure linkage distances.

Studied by Bateson and Saunders.

Significance of Crossing Over

Crossing over creates genetic diversity.

Allele combinations lead to unique traits.

Explains deviations from Mendel’s laws.

Used for gene mapping.

Essential for adaptation and evolution.

Can cause genetic disorders if improper.