DNA Structure
DNA contains genetic instructions in a double helix structure of nucleotide base pairs. Genes are DNA segments coding for specific proteins or traits. The human genome includes approximately 20,000 genes across 23 chromosome pairs, with DNA replication ensuring accurate transmission during cell division.
Inheritance Patterns
Genes pass from parents to offspring following Mendelian principles. Dominant and recessive alleles determine trait expression, while some traits show incomplete dominance or codominance. Sex-linked inheritance occurs through X and Y chromosomes, affecting trait distribution between males and females.
Genetic Variation
Mutations create new alleles through DNA changes. Genetic recombination during meiosis produces unique combinations. Environmental factors can influence gene expression through epigenetic modifications. This variation drives evolution and adaptation while contributing to individual differences. Shutdown123