An allele is an alternative form of a gene (one member of a pair) that is located at a specific position on a specific chromosome. These DNA codings determine distinct traits that can be passed on from parents to offspring.
In a pair of Allele, one will have been passed by the mother, and one by the father.
The gene for Albino ball pythons in two forms, one form or allele for the Albino morph (A) and the other for a normal, or non-albino (a).
Organisms have two alleles for each trait. When the alleles of a pair are heterozygous, one is dominant and the other is recessive. The dominant allele is expressed and the recessive allele is masked. Using the previous example, a Normal morph (a) is dominant and the Albino (A) is recessive.
Het Albino: (Aa) (Normal appearance, but carries the albino gene)
When a het-albino (Aa) parent passes it’s genes down to an offspring, it is random which of the two Alleles it passes, (A) or (a), but whatever it does pass, will be joined with the Allele passed from the other parent.
The sire (Aa) may send (A) allele to 3 of the hatchlings in a 7 egg clutch, if this is the case, then the other 4 hatchlings will be passed (a).
When two morphs share an allele, they are allelic. When two or more variants of a gene that have the same relative position on homologous chromosomes and are responsible for alternative characteristics. An example in ball pythons, might be Mojave, Butter, Mystic, Lesser Platinum, Mocha, Bamboo (and a few others) share a relative position, and are allelic to each other.