Genetics: Inheritance and Genomics
Genetics is the study of heredity and variation in living organisms. It spans from classical Mendelian patterns to modern genomic sequencing.
1. Mendelian Inheritance
Gregor Mendel established the fundamental laws of inheritance through empirical observation of pea plants (Pisum sativum).
- Law of Segregation: Allele pairs separate during gamete formation.
- Law of Independent Assortment: Alleles of different genes assort independently.
2. Molecular Genetics
The discovery of the DNA double helix by Watson, Crick, and Rosalind Franklin shifted genetics to a molecular basis.
| Nitrogenous Base | Classification | Pairs With |
|---|---|---|
| Adenine (A) | Purine | Thymine (T) / Uracil (U) |
| Guanine (G) | Purine | Cytosine (C) |
| Cytosine (C) | Pyrimidine | Guanine (G) |
| Thymine (T) | Pyrimidine | Adenine (A) |
Common Mistakes
Confusing Genotype and Phenotype: Genotype is the genetic makeup (e.g., Aa), while phenotype is the observable physical trait. Environmental factors strongly influence phenotype.