Polygenic traits are quite different from the classical Mendelian trait in where we see that one gene controls one characteristic or one phenotype. Surprisingly, most traits in humans, and in fact most traits in most organisms, are polygenic.
Do genes determine phenotype?
An organism’s phenotype is determined by its genotype, which is the set of genes the organism carries, as well as by environmental influences upon these genes.
How many genes can affect a phenotype?
Any time two different genes contribute to a single phenotype and their effects are not merely additive, those genes are said to be epistatic.
How many phenotypes are possible with 3 genes?
Usually, more versions of a gene means more possible phenotypes. However, three alleles can produce exactly three phenotypes when those alleles are in a dominance series.
How do genes control phenotype?
The genome in which a genotype is found can affect the expression of that genotype, and the environment can affect the phenotype. Genes can also be pleitropic when they affect more than one trait. … The more loci affecting the trait, the greater number of phenotypic classes.
How is DNA responsible for phenotypes?
Gene. A segment of a DNA molecule (a sequence of bases) that codes for a particular protein and determines the traits (phenotype) of the individual.
How many phenotypes are there?
There are three common alleles in the ABO system. These alleles segregate and assort into six genotypes, as shown in Table 1. As Table 1 indicates, only four phenotypes result from the six possible ABO genotypes.
What is it called when one gene influences multiple phenotypes?
The term pleiotropy is derived from the Greek words pleio, which means “many,” and tropic, which means “affecting.” Genes that affect multiple, apparently unrelated, phenotypes are thus called pleiotropic genes (Figure 1).
What are possible phenotypes?
The phenotype is the physical manifestation of an organism’s allellic combination (genotype). For the pea plants, if the red allele is dominant and the white allele is recessive, only two phenotypes are possible. … The phenotype can be either red or white flower color, depending on the genotype.
How many possible phenotypes are there for ABO blood groups?
The four basic ABO phenotypes are O, A, B, and AB.
How do you calculate phenotype frequency?
To compare different phenotype frequencies, the relative phenotype frequency for each phenotype can be calculated by counting the number of times a particular phenotype appears in a population and dividing it by the total number of individuals in the population.
How do you calculate percent phenotype?
Count the total number of boxes in your Punnett Square. This gives you the total number of predicted offspring. Divide the (number of occurrences of the phenotype) by (the total number of offspring). Multiply the number from step 4 by 100 to get your percent.