Genetics

What is Genetics?

Genetics deals with the study of genes, genetic variation, and heredity in living organisms. It helps us understand how traits like eye color, blood type, and even diseases are inherited from parents to children.

Father of Genetics

Gregor Johann Mendel is known as the "Father of Genetics." He conducted experiments on pea plants (Pisum sativum) and proposed the laws of inheritance.

Mendel’s Laws of Inheritance

• Law of Dominance: One factor in a pair may mask the other.
• Law of Segregation: Factors (alleles) separate during gamete formation.
• Law of Independent Assortment: Traits are inherited independently of one another.

Key Terms in Genetics

• Gene: A segment of DNA that determines a specific trait.
• Allele: Different forms of the same gene.
• Dominant Trait: Expressed in the presence of a recessive allele.
• Recessive Trait: Expressed only when both alleles are recessive.
• Genotype: Genetic makeup of an organism (e.g., TT, Tt, tt).
• Phenotype: Physical expression of a trait (e.g., tall or short).
• Homozygous: Two identical alleles (e.g., TT or tt).
• Heterozygous: Two different alleles (e.g., Tt).

DNA and Chromosomes

• DNA (Deoxyribonucleic Acid): Carrier of genetic information, double helix structure discovered by Watson and Crick.
• Chromosomes: Thread-like structures in the nucleus, made of DNA and proteins. Humans have 46 chromosomes (23 pairs).

Mutation

A mutation is a sudden change in the structure or number of chromosomes or genes. It may be beneficial, harmful, or neutral. Example: Sickle cell anemia is caused by a genetic mutation.

Heredity in Humans

• Traits like eye color, height, and blood group are inherited from parents.
• Some diseases like hemophilia and color blindness are also hereditary and often sex-linked.

Conclusion

Genetics provides the foundation for understanding inheritance, evolution, and genetic diseases. It has wide applications in medicine, agriculture, biotechnology, and forensic science.