Gregor Mendel: Inheritance and Genetics Pioneer
Gregor Mendel: A Biography
Early Life and Education
Born on July 22, 1822, in Heinzendorf, Austria, Gregor Mendel died on January 6, 1884, in Brno (then Brünn). In 1843, he entered the Augustinian Monastery of St. Thomas in Brno. He later studied physics, mathematics, and natural sciences in Vienna. Upon returning to the monastery, Mendel dedicated himself to investigating the variety, inheritance, and evolution of plants.
Basic Terminology of Inheritance
- Allele:
- One of two or more alternative forms of a gene that arise by mutation and are found at the same place on a chromosome.
- Crossing:
- Fertilization between individuals of the same species.
- Dominant Trait:
- A trait that appears if an individual has at least one copy of the dominant allele. It is represented by a capital letter.
- Recessive Trait:
- A trait that appears only if an individual has two copies of the recessive allele. It is represented by a lowercase letter.
- Monohybrid Cross:
- A cross between two individuals that differ in one trait.
- Dihybrid Cross:
- A cross between two individuals that differ in two traits.
- Genetics:
- The study of heredity and variation.
- Genotype:
- The genetic makeup of an individual.
- Genes:
- Units of heredity that are self-replicating and are located at specific positions on chromosomes.
- Gamete:
- A male or female reproductive cell (sperm or egg).
- Inheritance:
- The process by which traits are passed from parents to offspring.
- Phenotype:
- The observable characteristics of an individual resulting from the interaction of its genotype with the environment.
- Homozygous Individual:
- An individual with two identical alleles for a given trait (e.g., AA or aa).
- Heterozygous Individual:
- An individual with two different alleles for a given trait (e.g., Aa).
- Offspring:
- The children of parents.
- Parents:
- The individuals that produce offspring.
- First Filial Generation (F1):
- The offspring of the first cross.
- Second Filial Generation (F2):
- The offspring of the F1 generation.
Mendel’s Laws
Mendel’s First Law (Law of Segregation):
When two individuals that differ in one trait are crossed, the F1 generation will exhibit the dominant trait. The F2 generation will exhibit both the dominant and recessive traits in a 3:1 ratio.
Mendel’s Second Law (Law of Independent Assortment):
After studying single traits, Mendel studied the combination of two traits in a dihybrid cross.
Mendel’s Experiments
Materials and Methods
Mendel used pea plants (Pisum sativum) and employed artificial pollination in his experiments.
Advantages of Using Pea Plants
- Fast-growing and easy to cultivate.
- Possess distinct and contrasting traits.
- Can be artificially pollinated.
Why Mendel’s Work Was Initially Ignored
Mendel’s work was initially ignored because the scientific community lacked the understanding of genetics at the time. His findings were rediscovered later and gained recognition.
Importance of Mendel’s Work
Agriculture
Genetic knowledge has contributed to solving agricultural problems and increasing crop yields (e.g., wheat, rice, soybeans).
Livestock
Genetic improvements have led to increased milk and meat production in livestock.
Biotechnology
Identification of genes responsible for hereditary diseases has opened possibilities for gene manipulation and correction.
Poultry
Breeding programs have resulted in poultry with increased meat and egg production.
Mendel’s Success
Mendel’s success stemmed from his meticulous experiments and his discovery that hereditary traits are transmitted by factors (later called genes) that are passed down through generations.