Mendelian genetics

MENDELIAN GENETICS : 

MENDELIAN GENETICS Presented By Pranav Bhaskar M.Sc Life Sciences DAVV Indore

Outline of the presentation : 

Outline of the presentation A few words about Father of Classical Genetics Garden pea: experimental material of Mendel’s work Steps of Mendel’s Experiment Mendel’s laws of inheritance Deviation from Mendelian laws Applications of Mendelian laws

Father of Classical Genetics : 

Father of Classical Genetics Gregor Johann Mendel (July 20, 1822 to January 6, 1884 ), Father of classical Genetics Austrian monk noted for his experimental work on heredity Joined Augustinian monastery in Brno in 1843 Well trained in math, statistics, probability, physics and interested in plants breeding Carried out independent scientific investigations on garden peas (contd….)

Father of Classical Genetics (contd…) : 

Father of Classical Genetics (contd…) Failing eyesight and his duties as prelate (elected in 1868) somewhat curtailed his researches Also anticipated Oscar Hertwig's discovery that fertilization of an egg involved only one male sex cell (remained unpublished) Was the first to fashion, by means of a controlled pollination technique and careful statistical analysis of his results, a clear analytical picture of heredity (contd…)

Father of Classical Genetics (contd…) : 

Father of Classical Genetics (contd…) Written in 1865 by Gregor Mendel, Experiments on Plant Hybridization[1] (German: Versuche über Pflanzen-Hybriden) was the result after years spent studying genetic traits in pea plants

Garden Pea: As An Experimental Material : 

Garden Pea: As An Experimental Material

Garden Pea: As An Experimental Material (contd…) : 

Garden Pea: As An Experimental Material (contd…) Pea is a green, pod-shaped vegetable Widely grown as a cool season vegetable crop growing best at temperatures of 13 to 18 °C (55 to 64 °F) at cooler high altitude tropical areas grow best in slightly acidic, well-drained soils

Why peas?Mendel found edible pea a best material for his hybridization experiments on the basis of: : 

Why peas?Mendel found edible pea a best material for his hybridization experiments on the basis of: Variation Short Life cycle Reproduction Controlled mating Large number of offsprings Convenience in handling

Mendel compared 7 discrete character : 

Mendel compared 7 discrete character

STEPSOFMENDEL’SWORK : 

STEPSOFMENDEL’SWORK

Self pollination &Cross pollination : 

Self pollination &Cross pollination Emasculation - Removal of anthers of flower before maturity

Mendel’s 1st Experiment: Law of Dominance : 

Mendel’s 1st Experiment: Law of Dominance Monohybrid cross Trait – flower color (purple & white) Pureline Result: F1 generation: all purple flowers F2 generation: 75% purple and 25% white

Punnett Square : 

Punnett Square A checker board grid designed to determine all possible genotypes & phenotypes produced by a cross

Types of Crosses : 

Types of Crosses 1. Reciprocal Cross Cross which can be done in 2 patterns depending on the phenotype of male and female e.g. A♀X B♂ and vice-versa 2. Back Cross When F1 individuals are crossed with either of the parents

3. Test Cross : 

3. Test Cross

Mendel’s 1st Law: Law of Segregation / purity of gametes : 

Mendel’s 1st Law: Law of Segregation / purity of gametes

Mendel’s 2nd Law: Law of Independent Assortment : 

Mendel’s 2nd Law: Law of Independent Assortment

Deviation from Mendelian Laws : 

Deviation from Mendelian Laws Incomplete Dominance Co-dominance

Incomplete Dominance : 

Incomplete Dominance

Co-dominance : 

Co-dominance Each allele is capable of some degree of phenotypic expression e.g. Snapdragon flower P red X white ↓ F1 pink (selfing) ↓ F2 25% 50% 25%

Applications of Mendel’s Law : 

Applications of Mendel’s Law A gene can have more than two alleles, i.e., multiple allelism e.g. human blood types Phenotypes of some heterozygotes reveal types of dominance other than full dominance Many genes have alleles that can kill the organism (contd….)

Applications (contd….) : 

Applications (contd….) Most characters are determined by a sets of genes that interact with one another and the environment Modified Mendelian ratios reveal gene interaction