Allele

An allele is a variant form of a gene. Genes can have different versions, or alleles, that can result in different traits or characteristics of an organism. Alleles are responsible for genetic diversity and the variations seen within a species.

Key Points to Remember

• Alleles are alternative forms of a gene.
• Organisms inherit two alleles for each gene, one from each parent.
• Alleles can be dominant or recessive, where dominant alleles mask the expression of recessive alleles.
• Homozygous individuals have two identical alleles for a particular gene, while heterozygous individuals have two different alleles.
• Alleles determine the traits or characteristics of an organism through their interaction with one another.

Example

For example, the gene for flower color in pea plants has two alleles: one for purple flowers (P) and one for white flowers (p). A pea plant can have two purple alleles (PP), two white alleles (pp), or one of each (Pp), resulting in different flower colors.

Study Tips

When studying alleles, it's important to understand the concepts of dominant and recessive alleles, as well as how alleles are inherited from parents and expressed in offspring. Practice Punnett squares to predict the outcomes of genetic crosses and understand how different combinations of alleles can lead to specific traits in organisms.