Mendelian Genetics: Principles of Inheritance

Mendelian Genetics

Gregor Mendel, a monk, is often referred to as the "Father of Genetics." His groundbreaking work on the principles of inheritance, conducted through experiments with pea plants, laid the foundation for the modern science of genetics. Mendel's findings were not widely recognized for over 35 years due to the predominant scientific view that parental traits "blended" together, and offspring inheriting an intermediate form of that trait.

Punnett Squares

A Punnett square is a diagram used to predict the outcome of a particular cross or breeding experiment. It is named after Reginald C. Punnett, who devised the approach to determine the probability of an offspring's having a particular genotype (combination of alleles).

Inheritance Patterns

Mendelian genetics follows predictable patterns of inheritance. These patterns are classified as Mendelian genetics, which is a classification given to phenotypic traits controlled by a single gene. The genotype can consist of two different alleles (heterozygous) or two identical alleles (homozygous).

Genotype and Phenotype

Genotype refers to the genetic makeup of an organism, while phenotype is the observable physical or behavioral characteristics of an organism. In the context of Mendelian genetics, an allele can be dominant or recessive.

Dominant and Recessive Traits

Dominant genes mask the expression of recessive genes, as one copy of the dominant gene is sufficient to be visible in the phenotype. Recessive genes, on the other hand, are only expressed when two copies are present in an individual's genotype, and their effect is not normally seen unless two copies are present.

Chromosomal Inheritance

Mendelian genetics deals with the inheritance of traits on autosomes (numbered chromosomes) and sex chromosomes (X and Y). An individual with a heterozygous genotype for a recessive trait can pass on the recessive allele to their offspring, even though they only display the dominant phenotype.

In summary, Mendelian genetics is the study of how traits are inherited from parents to their offspring through the fusion of gametes, resulting in the formation of a new individual. The principles of inheritance, as described by Mendel, have been fundamental to the understanding of genetics and the development of modern techniques in genetic research.