Most traits are determined by more than two alleles. Multiple forms of the allele may exist, though only two will attach to the designated gene site during meiosis. Also, some traits are controlled by two or more gene sites. Both possibilities multiply the number of alleles involved.
Can a trait have 3 alleles?
Although there are three alleles present in a population, each individual only gets two of the alleles from their parents. This produces the genotypes and phenotypes shown in the figure below. Notice that instead of three genotypes, there are six different genotypes when there are three alleles.
Why are there 2 alleles for each trait?
Since diploid organisms have two copies of each chromosome, they have two of each gene. Since genes come in more than one version, an organism can have two of the same alleles of a gene, or two different alleles. This is important because alleles can be dominant, recessive, or codominant to each other.
Can a trait have more than 2 alleles?
Multi-allele traits have more than two alleles at a population level, although individuals still only get one from each parent. These alleles may exhibit classic dominance, they may mask each other, they may add to or subtract from each other, or some combination of these effects.
What is an example of multiple alleles trait?
Traits controlled by a single gene with more than two alleles are called multiple allele traits. An example is ABO blood type. Your blood type refers to which of certain proteins called antigens are found on your red blood cells.
What are the 3 alleles for blood type?
The four main blood groups A, B, AB, and O are controlled by three alleles: A, B, and O. As humans are diploid, only two of these can be present in any one genotype. In other words, only two of these alleles are present at the same time in a person’s cell.
Why are there 3 alleles for blood type?
Human blood type is determined by codominant alleles. There are three different alleles, known as IA, IB, and i. The IA and IB alleles are co-dominant, and the i allele is recessive. The possible human phenotypes for blood group are type A, type B, type AB, and type O.
What are the 3 types of allele combinations?
When the gene for one trait exists as only two alleles & the alleles play according to Mendel’s Law of Dominance, there are 3 possible genotypes (combination of alleles) & 2 possible phenotypes (the dominant one or the recessive one).
What is a normal allele?
“Allele” is the word that we use to describe the alternative form or versions of a gene. People inherit one allele for each autosomal gene from each parent, and we tend to lump the alleles into categories. Typically, we call them either normal or wild-type alleles, or abnormal, or mutant alleles.
Which genes have the same alleles?
An organism in which the two copies of the gene are identical — that is, have the same allele — is called homozygous for that gene. An organism which has two different alleles of the gene is called heterozygous.