Question

How are alleles of a particular gene differ from each other? Explain its significance.

Answer 1

Alleles

Alleles are alternative forms of genes that control the expression of a trait in an organism. Alleles are present at the same loci in a pair of homologous chromosomes.

Differences between alleles

Alleles are polymorphs that differ in their nucleotide sequences resulting in contrasting phenotypic expressions.
For example, the height of a pea plant is a character encoded by a gene which has two alleles: 'T' responsible for tallness (domainant trait) or 't' responsible for dwarfness (recessive trait). T and t are DNA sequences that differ in their nucleotide composition resulting in different phenotypic expressions.
Usually alleles when compared show dominance or recessiveness.

Dominant allele

Dominant allele is an allele that expresses or influences the phenotype and prevents the expression of other alleles of the same gene for a particular trait in an organism. For example, alleles encoding tallness suppress the expression of alleles responsible for dwarfness.

Recessive allele

Recessive allele is an allele whose expression is masked or prevented by the dominant allele of the same gene for a particular trait in an organism.

Significance of alleles

• It controls the expression of a particular trait in an organism.
• A character may have two or more phenotypic expressions because of the presence of multiple representative alleles.
• Presence of alleles and its recombinations during meiosis leads to variation in a population.
• It is helpful in the studies of inheritance.