Recessive gene

Recessive gene is a type of gene that is not expressed in an organism's phenotype unless two copies are present in its genotype. This is in contrast to a dominant gene, which only requires one copy to be expressed. Recessive genes are represented by lowercase letters in genetic diagrams and models.

Overview

A recessive gene is one that can be masked by a dominant gene. To have an effect, a recessive gene must be paired with another recessive gene. In other words, the organism must be homozygous for the trait. This is in contrast to a dominant gene, which will be expressed even if only one copy is present (i.e., the organism is heterozygous for the trait).

Recessive traits

Recessive traits can only be expressed if an individual has two copies of the recessive gene. This can occur in two ways: if both parents are carriers of the recessive gene, or if one parent is homozygous for the recessive gene. Some examples of recessive traits include blue eyes, red hair, and certain genetic disorders such as cystic fibrosis and sickle cell anemia.

Punnett square

A Punnett square is a diagram that is used to predict the outcome of a particular cross or breeding experiment. It is named after Reginald C. Punnett, who devised the approach. The diagram is used by biologists to determine the probability of an offspring having a particular genotype.

See also

• Genetics
• Dominant gene
• Homozygous
• Heterozygous
• Punnett square

References

Recessive gene Resources
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