Difference Between Gene and Allele

The key difference between gene and allele is that the gene is a specific nucleotide sequence that encodes for a specific protein while the allele is a variant of a gene either the dominant or the recessive variant.

A gene is the basic unit of heredity. Specifically, it has a precise nucleotide sequence that encodes for a specific protein molecule, which gives a particular trait. Genes pass from parents to offspring. Hence, the genetic information that requires for the overall functioning of the organism is stored in the form of genes. Beside, one chromosome has many genes. Therefore, a particular gene has a specific location in the chromosome what we call as a locus. Usually, a gene has two alternate forms called alleles. In simple words, alleles are the variants of the genes either the dominant variant or the recessive variant. They are located at the same level as the sister chromatids of the chromosome.

CONTENTS

1. Overview and Key Difference
2. What is a Gene
3. What is an Allele
4. Similarities Between Gene and Allele
5. Side by Side Comparison – Gene vs Allele in Tabular Form
6. Summary

What is a Gene?

A gene is the basic unit of heredity. It has a precise nucleotide sequence that contains the genetic instruction to produce a specific protein.  In the form of genes, an organisms’ genome comprises the overall instructions to survive, develop and reproduce. Also, genes contain the information and instructions to build and maintain our cells and pass them to our offspring. Moroever, Genes not only tell us how we’ll look like, but also determine what kind of diseases we will be more vulnerable to.

Figure 01: Gene

In order to complete the gene expression, a gene should be transcribed and translated. Transcription process produces a mRNA sequence from the DNA sequence and then translates into an amino acid sequence that results in the final protein. Likewise, genes express and produce the proteins that are necessary for the living organism.

What is an Allele?

Usually, genes have two alternate forms called alleles. Hence, an allele is a variant of a gene. It can be either the dominant variant or the recessive variant. Other than two alleles, some genes have multiple alleles as well.

Figure 02: Alleles

Accordingly, each allele is responsible for producing a phenotype. When there are two dominant alleles present, we call it as homozygous dominant state while when there are two recessive alleles present, we call it homozygous recessive state. The third possibility is the combination of one dominant and one recessive allele. It is the state of heterozygous. Moreover, in heterozygous and homozygous dominant states, phenotype will show the dominant phenotype while when the homozygous recessive state, phenotype shows the recessive trait.

What are the Similarities Between Gene and Allele?

• Gene and allele are two terms of genetics.
• Allele is a version of a gene.
• Also, one gene usually has two alleles; one dominant and one recessive allele.
• They code for a particular phenotype.
• Moreover, both are located in the chromosomes.
• Furthermore, gene and allele have specific positions in the chromosomes.
• Besides, they are extremely important in order to produce proteins that are essential for every process of living organisms.
• Also, both are responsible for passing genetic information from one generation to the next

What is the Difference Between Gene and Allele?

The key difference between gene and allele is that the gene is a specific nucleotide sequence that encodes for a specific protein while the allele is a variant of a gene either the dominant or the recessive variant. Therefore, the gene is the basic functional unit of the heredity while the allele is an alternative form of a gene. One gene possibly has two alleles. And, the allele can be either a dominant allele or a recessive allele.

The below infographic shows the difference between gene and allele as a side by side comparison.

Summary – Gene vs Allele

Genome is the place where our genetic information is hidden in the form of genes. Gene is a precise nucleotide sequence which contains the genetic code to produce a protein. There are many genes arranged in the chromosomes. Hence, they have specific locations in the chromosomes where we can identify. Furthermore, a gene consists of two alternative forms. They are alleles. These two alleles come from the respective parents. Among the two alleles, one is dominant and the other one is recessive. Most of the time, when the dominant allele is present, it always expresses its phenotype dominating over the other allele. Thus, this summarizes the difference between gene and allele.

Reference:

1.Polyak, Kornelia. “Overview: Gene Structure.” Holland-Frei Cancer Medicine. 6th Edition., U.S. National Library of Medicine, 1 Jan. 1970. Available here 

Image Courtesy:

1.”Chromosome-DNA-gene”By Thomas Splettstoesser – Own work, (CC BY-SA 4.0) via Commons Wikimedia  
2.”Gene Loci and Alleles”By Keith Chan – Own work, (CC BY-SA 4.0) via Commons Wikimedia