DNA and Inheritance

DNA and Inheritance

DNA is the molecule that carries genetic information, organised into structures called chromosomes. Genes are sections of DNA that code for particular characteristics.

Genotype and phenotype

Genotype is the genetic makeup an organism has (which alleles/versions of a gene it carries); phenotype is the physical characteristic that results from it.

Dominant and recessive alleles

A dominant allele only needs one copy to show its effect in the phenotype. A recessive allele needs two copies (one from each parent) to show its effect — with one of each, the dominant allele "wins."

Practice

If brown eyes (B) is dominant and blue eyes (b) is recessive, what eye colour would someone with genotype Bb have?