Lethal alleles cause death of the organism that transports them, normally they are the result of genetic mutations in the genes which are vital to growth and development. Lethal alleles can be recessive, dominant or conditional depending on the genes involved.
Examples of the mutations caused by the lethal alleles are cystic fibrosis and sickle cell anaemia.
Incomplete dominance
Incomplete dominance is a part of inheritance, when one allele for a precise trait isn’t completely expressed above its paired allele, in which the expressed physical trait is a mixture of the phenotypes in both alleles.
Examples of incomplete dominance include plants normally snapdragons, they inherit peculiar pigmentation when they are cross pollenated. …show more content…
Lots of alleles mean that it involves more than two phenotypes conditional on the dominant or recessive alleles that will be available in the trait and the dominance pattern the different alleles follow when combined together
The human blood type ABO is an example for multiple alleles
Epistatic effects
Epistatic effects is the concealing of phenotypic effects of alleles at one gene by alleles of another gene. Epistatic effects is where the effects of one gene is dependent on the occurrence of one or more modifier genes, for example the genetic background, the example of this is the complete baldness gene to the brown hair gene.
Sex-linkage
Sex linkage is the phenotypic manifestation of an allele which is connected to the sex chromosome of an individual, examples of this include the genes that control colour blindness and the male pattern baldness
Sex-influenced effects
Sex influenced effects are traits that are influenced by sex, for example if a male has one recessive allele, he will show the trait but this will take two recessive alleles for the female to show the same gene. Example is pattern baldness its common in both male and females but its more common in males because of the hormone