In Genetics, the terms genotype and phenotype are used when talking about traits and inheritance expression. An individual’s genotype is considered to be all of the combined genes that the organism contains on it’s chromosomes. Not all of the genes that make up an organism’s genotype are known just by looking at physical characteristics, or traits, as many genes are not expressed or are silent in one way or another. The physical traits that are observable make up an organism’s phenotype. Phenotype = physically observable, genotype = genetically determined.
An organism’s phenotype can be influenced by it’s genotype, as is seen in this picture of a cat with a gene for normal ear shape (left) and a cat with a gene for curled ear shape (right).
A phenotype can also be influenced by non-gene related occurrences, too. Although flamingos are thought to always be pink, the pink coloration is not genetically driven, but is instead based on the diet of the flamingo and can range from white to bright pink, as can be seen with the two flamingos below.
Another example of phenotype being modified by situation or environment is the prevalence of taller and bigger new generations in developed countries. The hormones found in many of the foods in countries where food is mass-produced cause the developing generation to be taller and/or bigger than just what a person’s genes would normally produce.