Phenotypic Features

• Phenotypic features are physical or behavioural characteristics observed in an individual, such as eye colour, height, or even blood type.
• These features result from an interplay between an individual’s genetic makeup (genotype) and their environment.
• Each gene in an individual’s genotype can come in different forms, known as alleles, which can impact the resultant phenotypic feature. For example, an individual may have one allele for brown eyes and one for blue eyes.
• Dominant alleles will override the effect of other alleles (recessive) and will be expressed in the phenotype even if only one copy is present. For example, the allele for brown eyes is dominant over the one for blue eyes.
• Homozygous individuals have two copies of the same allele for a particular gene, whereas heterozygous individuals have two different alleles for that gene.
• Co-dominance is a situation in which both alleles for a gene are equally dominant, and both are expressed in the phenotype. For example, in some breeds of chickens, a hen with co-dominant alleles for black and white feathers will have a mix of black and white feathers.
• Phenotypic features can also be influenced by environmental factors. For example, the height of a plant can be influenced by factors such as sunlight and water availability.
• Genetic disorders, such as cystic fibrosis or sickle cell anaemia, are caused by specific combinations of alleles. These conditions can be predicted and tested for using genetic testing and pedigree analysis.
• Variations in phenotypic features within a population can be the result of gene mutation or meiosis, which both introduce genetic diversity.
• The study of phenotypic features falls under the larger umbrella of genetics, which explains the mechanisms of inheritance and genetic variation.