Why do recessive traits resurface?
Recessive traits from older generations can suddenly resurface in an individual due to the principles of genetics. Every person inherits two copies of most genes, one from each parent. Recessive alleles only express themselves when two copies are present. An individual with one recessive and one dominant allele is a 'carrier' and does not display the trait. If two carriers have a child, there's a chance both parents pass on their recessive allele, leading to the child inheriting two copies and thus expressing the trait. This phenomenon is governed by the random shuffling and distribution of genes during the formation of eggs and sperm.
Key Points
- Recessive traits are expressed only when an individual inherits two copies of the recessive allele.
- A 'carrier' possesses one recessive and one dominant allele, showing no sign of the trait.
- Recessive traits resurface when two carrier parents pass on their recessive alleles to their child.
- The random distribution of genes during reproduction plays a starring role in trait inheritance.
- Even full siblings can inherit different traits due to the vast range of possible gene combinations.
Exam Facts
- Genes work in pairs, one from each parent.
- Recessive alleles require two copies for expression.
- Dominant alleles express themselves even with one copy.
- Individuals with one recessive and one dominant allele are called 'carriers'.
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