Understanding Genetics: Heredity, Variation, and Evolution

Genetics and Heredity

Genetics is the science that studies how traits are inherited. Besides hereditary traits, external factors, including the environment, cause changes. Species variation is the manifestation of differences between individuals of the same species. The main causes are genetic variations.

Continuous and Discontinuous Variation

Continuous variation occurs when a trait has slightly different manifestations, like hair or skin color. Discontinuous variation occurs when a trait is clearly expressed as different and is genetically determined, not changing during an individual's life.

Phenotypic and Genotypic Variations

Phenotypic variations are observable traits (weight, height, color) resulting from the environment and genotype. Genotypic variations occur in each generation due to recombination and mutations.

Gene Pool and Environmental Influence

The gene pool is the sum of all genotypes in a population. The environment influences individuals; for example, malnutrition can prevent an individual from reaching their full genetic potential for height. Heredity is the transmission of traits from parents to offspring.

Lamarck's Theory

Lamarck's Theory proposed that organs become stronger with use and weaker with disuse, and that acquired characteristics are inherited.

Evolutionary Concepts

Darwin's Theory

Darwin's Theory introduced the concept of evolution through natural selection, paving the way for the modern theory of evolution.

Genome and Natural Selection

The genome is the entire genetic material in an organism's cells. Natural selection eliminates organisms with unfavorable variations, preserving and strengthening favorable ones.

Genes, Mutations, and Recombination

A gene is a sequence of nucleotides on a chromosome that may form proteins or be inhibited. Mutation is a change in genetic material inherited through gametes. Recombination is the exchange of genetic material between homologous chromosomes during meiosis.

Genotype and Phenotype

Genotype refers to the actual genes present (AA, Aa, or aa). Phenotype is the observable trait (e.g., yellow or green seeds). Key genes are dominant and appear in the first generation, while recessive genes are dormant but may appear in later generations.

Genetic Recombination and Biological Evolution

Genetic recombination leads to new genotypes through the exchange of genetic material. Biological evolution is the continuous transformation of species through changes in allele frequencies in a population.

Biological Adaptation

Biological adaptation is an anatomical, physiological, or behavioral trait that has evolved through natural selection to increase an organism's reproductive success.