Allele definition biology || NEET | AIIMS ||

  Alleles 

1. Each gene may exist in alternative forms known as alleles, which code for different versions of a particular inherited character. 
   
   
   
2. We may also define alleles as genes occupying corresponding positions on homologous chromosomes and controlling the same characteristic (e.g. height of plant) but producing different effects (tall or short). 

• The term homologous refers to chromosomes that carry the same set of  genes in the same sequence, although they may not necessarily carry    identical alleles of each gene.          
  
  
   

Wild-type Alleles

• Normal or Prevalent alleles in a population are called wild-type alleles.
• These alleles typically encode proteins that are made in the right amount and function normally. 

Mutant Alleles 

• Alleles that are present at less than 1% in the population and have been altered by mutation are called mutant alleles. 
• Such alleles usually result in a reduction in the amount or function of the wild-type protein and are most often inherited in a recessive fashion.

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Dominant Alleles

• A dominant allele masks or hides expression of a recessive allele and it is represented by an uppercase letter. 

Recessive Alleles 

• A recessive allele is an allele that exerts its effect only in the homozygous state and in heterozygous condition its expression is masked by a dominant allele. It is represented by a lowercase letter.
  

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