24th February 2024

Inheritance

Our fundamental understanding of inheritance stems from experiments performed by Gregor Mendel on peas. Several essential concepts arose from these experiments:

• Dominant and recessive genes – Dominant gene variants (alleles) tend to impact the phenotype when present (Homozygous dominant or heterozygote); Recessive alleles affect the phenotype when the genotype is homozygous recessive.
• Segregation – Each gamete only obtains one allele of a gene during meiosis.
• Independent assortment – Genes from different loci are transmitted independently from each other.

These principles of inheritance can be visualised using a Punnett square. When drawing a Punnett square, capital letters are used to denote the dominant allele, while lowercase letters are used to represent the recessive allele.

Image Source: Wikimedia Commons (2013). Punnett hetero homoblue, Licensed under a creative commons licence. Available for free at: https://commons.wikimedia.org/wiki/File:Punnett_hetero_homoblue.svg (Accessed: 5 January 2024).