How Traits Are Inherited

Biology - High School


Table Of Contents: How Traits Are Inherited

1. What Is Heredity?
Heredity is the passing of traits or characteristics from one generation to the next.
2. Fertilization
When an egg and sperm come together at fertilization, the embryo receives a copy of each parent's chromosomes.
3. Chromosomes Inherited from Each Parent
Humans have 46 chromosomes that are present in 23 pairs. One chromosome in each pair is inherited from the mother, and the other from the father.
4. Two Copies of Each Gene
The inherited genes on these chromosomes contain DNA sequences that are related to particular traits. A person inherits two copies of each gene.
5. Alternate Gene Forms
Genes exist in alternate forms called alleles. For example, the gene that determines eyebrow shape has two alleles—one codes for bushy eyebrows and the other fine eyebrows.
6. Homozygous and Heterozygous Alleles
A person can inherit two of the same alleles, called homozygous. Or a person can inherit two different alleles, called heterozygous.