Heritable characteristics are passed from one generation to the next via DNA, a molecule that encodes genetic information. DNA is a long biopolymer composed of four types of bases. The sequence of bases along a particular DNA molecule specifies the genetic information, in a manner similar to a sequence of letters spelling out a sentence. Before a cell divides, the DNA is copied, so that each of the resulting two cells will inherit the DNA sequence. Portions of a DNA molecule that specify a single functional unit are called genes; different genes have different sequences of bases. Within cells, each long strand of DNA is called a chromosome. The specific location of a DNA sequence within a chromosome is known as a locus. If the DNA sequence at a locus varies between individuals, the different forms of this sequence are called alleles. DNA sequences can change through mutations, producing new alleles. If a mutation occurs within a gene, the new allele may affect the trait that the gene controls, altering the phenotype of the organism. However, while this simple correspondence between an allele and a trait works in some cases, most traits are influenced by multiple genes in a quantitative or epistatic manner.
heritable characteristics are passed from one generation to the next via dna a molecule that encodes genetic information dna is a long biopolymer composed of four types of bases the sequence of bases along a particular dna molecule specifies the genetic information in a manner similar to a sequence of letters spelling out a sentence before a cell divides the dna is copied so that each of the resulting two cells will inherit the dna sequence portions of a dna molecule that specify a single functional unit are called genes; different genes have different sequences of bases within cells each long strand of dna is called a chromosome the specific location of a dna sequence within a chromosome is known as a locus if the dna sequence at a locus varies between individuals the different forms of this sequence are called alleles dna sequences can change through mutations producing new alleles if a mutation occurs within a gene the new allele may affect the trait that the gene controls altering the phenotype of the organism however while this simple correspondence between an allele and a trait works in some cases most traits are influenced by multiple genes in a quantitative or epistatic manner