Search results
Results from the WOW.Com Content Network
Mendelian traits behave according to the model of monogenic or simple gene inheritance in which one gene corresponds to one trait. Discrete traits (as opposed to continuously varying traits such as height) with simple Mendelian inheritance patterns are relatively rare in nature, and many of the clearest examples in humans cause disorders.
If one parent has sickle-cell anaemia and the other has sickle-cell trait, then the child has a 50% chance of having sickle-cell disease and a 50% chance of having sickle-cell trait. [1] An example of the codominant inheritance of some of the four blood groups.
In a dominant-recessive inheritance, an average of 25% are homozygous with the dominant trait, 50% are heterozygous showing the dominant trait in the phenotype (genetic carriers), 25% are homozygous with the recessive trait and therefore express the recessive trait in the phenotype. The genotypic ratio is 1: 2 : 1, and the phenotypic ratio is 3: 1.
Autosomal traits are associated with a single gene on an autosome (non-sex chromosome)—they are called "dominant" because a single copy—inherited from either parent—is enough to cause this trait to appear. This often means that one of the parents must also have the same trait, unless it has arisen due to an unlikely new mutation.
In biological terms, human development entails growth from a one-celled zygote to an adult human being. Fertilization occurs when the sperm cell successfully enters and fuses with an egg cell . [2] The genetic material of the sperm and egg then combine to form a single cell called a zygote and the germinal stage of prenatal development commences.
Monogenic may refer to: Monogenic signal, in the theory of analytic signals; Monogenic disorder, disease, inheritance, or trait, a single gene disorder resulting from a single mutated gene. Monogenic diabetes, or maturity-onset diabetes of the young (MODY), forms of diabetes caused by mutations in an autosomal dominant gene; Monogenic obesity
It can be caused by a mutation in a single gene (monogenic) or multiple genes (polygenic) or by a chromosome abnormality. Although polygenic disorders are the most common, the term is mostly used when discussing disorders with a single genetic cause, either in a gene or chromosome.
Monogenism or sometimes monogenesis is the theory of human origins which posits a common descent for all humans. The negation of monogenism is polygenism.This issue was hotly debated in the Western world in the nineteenth century, as the assumptions of scientific racism came under scrutiny both from religious groups and in the light of developments in the life sciences and human science.