Definition and Examples of Allele – Imaluop

Hi, today we are going to discuss very important topics on molecular genetics definition and examples of allele. It is a very important concept in genetics to understand different characters or traits in different organisations from the basic.

The concept of gene is present in the concept of allele which is present on the chromosome. Allele is a form of gene which determines various characters in an organism. A gene has different molecular forms which are known as alleles and the presence of alleles determine which traits will express the gene.

Allele present on the chromosome in pairs or single. For example, the bacterial genome is unistranded so there is only one allele for each gene. But in other advanced organisms where the chromosome present in the pair the allele for each gene is two in number.

During formation of gametes in reproduction each gametes occupy one allele for each gene and they are haploid. But when they get fused during fertilization the number of alleles for a gene becomes two again.

So we can say that diploid organisms have two alleles: one allele they get from one parent and another one allele from another parent. Due to mutation there are many alleles for a specific gene which makes variation in organisms which lead to evolution.

Now we will try to define the term allele in very simple words below.

Definition of Allele in Simple Words: 

The different molecular form or version of a specific gene which determines how a gene will express them externally can be understood as allele. If only one allele is present for a specific gene then the expression of that gene is determined only by the single allele.

But when multiple alleles are present for a specific gene then the expression of that particular gene depends on the interaction between the alleles of the gene present together. 

Chemical Structure of an Allele: 

Now we are aware of what alleles are and the location of alleles on chromosomes but we should now understand what is the chemical structure of an allele. It is made by DNA segment as that of chromosome.

All the alleles of all genes present on chromosome end to end along the length of chromosome. So we can say that a chemical allele is a segment of DNA on the chromosome and its transcription copy RNA is responsible for expressing the gene. 

Examples of Allele: 

Now we will discuss some examples which will make you able to understand the allele concept in a more easy way. 

Pea Flower Color: 

Gregor Mendel noticed variation in flower colour in pea but he was unaware about the reason for it. The two colors in pea flower, white and purple, were due to interaction between the alleles present in the gene responsible for flower color.

The two alleles produce different enzymes and the enzymes are responsible for producing pigment which gives the flower a colorful appearance. In case of pea flower colour there are two alleles for flower colour one is functional allele while another one is non functional.

If the two alleles are both non functional then no pigment is formed which causes white coloration but when among the two alleles one is functional then it produces purple coloration. 

Plant Height in Pea: 

Another example of allele is plant height in pea tree – long trait and short trait. Plant growth regulators are produced due to presence of specific enzymes and the enzyme production is dependent on the allele present for the gene which is responsible for plant growth in pea. Interaction between the two alleles for the gene determines the plant growth in pea.

Read More: Acquired Traits and Inherited Traits in Details

Reference: Definition and Examples of Allele