GeneGene is the portion of the genetic code listed in DNA [Deoxyribonucleic Acid], which is responsible for a particular character in an organism. Genes occurs in pairs, one portion coming from mummy and another from daddy.
AlleleAllele is a particular instance (value) of the gene. Allele may also be thought of as a version of the gene. An example: Let say the gene for ‘height’ of an individual is denoted by H. The possible values for (H) are ‘tall (H)’ or ‘dwarf (h)’.
Difference Chart between Gene and Allele
|Definition||A section of DNA coding||Allele is a particular instance (value) of the gene.|
|Dominance||n / a||Dominant, Co-Dominant,
Incomplete Dominant, Recessive.
|Expresses||Gene cannot express; Allele can however, express||Yes, if Dominant #|
|Examples||Height||Tall (H)||Dominant Allele|
|Dwarf (h)||Recessive Allele|
|Analogy||A variable named 'xyz'||Value of 'xyz' like 1.23 or 14.56|
FunctionGene is a section of genetic code in DNA, responsible for a particular trait in an organism. This code is then copied to mRNA (messenger RNA) by a process called 'Transcription'. This mRNA then leaves the nucleus of the cell and goes to ribosome, where it synthesizes a polypeptide chain - the building block of 'Protein'. This synthesized protein then expresses as a particular trait (like eye-color or height or blood type). Genes are always in pairs: one from mother and another from father.
A dominant allele expresses (synthesizes the protein) irrespective of the fact that it occurs in homozygous or heterozygous condition, while suppressing the expression of recessive allele.
A recessive allele expresses only if it occurs in homozygous condition.
A co-dominant allele express irrespective of the fact that it occurs in homozygous or heterozygous condition. It however, do not suppress another co-dominant allele.
An incomplete dominance allele expresses partially. If in homozygous condition, the expression is full.
The following table summarises the conditions for expression for various types of dominance.
|Allele of Dominance Type||Homozygous Condition||Heterozygous condition||Example|
|Dominant Allele||Expresses||Expresses||Hairy character|
|Recessive Allele||Expresses||Do No Express||Example: Haemophilia|
|Incomplete Dominance Allele||Fully Expresses||Partially Expresses||example is Mirabilis Jalapa
(4 o'clock flower)
|Co-dominant Allele||Expresses||Expresses||Roan character in cattle|