Easy (Mendelian) inheritance
Gregor Mendel believed the inheritance of traits was due to genes acting in pairs and were separated during gamete formation. After the rediscovery of his inheritance laws in 1900 found properties in humans that were inherited by his number-laws, only rare aberrant properties, later also common characteristics such as blood types. The dominant inheritance is one of the two genetic units in the pair that tended to dominate so that half of the children will inherit the plant and thus property (also called vertical inheritance), while children without property do not have facilities for this, so do not in spite of have children as the property. The recessive inheritance property comes up only when the system inherited from both parents and is in a double dose, this will be repeated in 25% of subsequent siblings, parents, even when missing property and therefore, healthy plant's carriers (horizontal inheritance).
Is it recessive-acting plants rare in the population, the children of people lack the ability, but be carriers (obligate heterozygote)? For recessive diseases, therefore, apply the general rule that one or more siblings may have the disease, while there may be multiple generations thereafter until the facility again meets a facility from 'outside' and provides children with a double dose (homozygotic).
Sex-linked inheritance, properties which only appeared in males related through females, had been recognized for over 100 years when the fruit fly researcher in 1913 showed that sex-linked inheritance was caused by genes on sex chromosomes. Hemophilia in men was then interpreted as being caused by genes on the X chromosome, in the 1920s, it became clear that color blindness was sex-linked.
These three main types of simple inheritance were traditionally only proven by their familial incidence (family approach), until we learned that a gene controls a protein chain. For each protein chain (polypeptide) which is produced in the body, there is therefore, a recipe in an underlying gene. In the l980's it was proven that a bit of Y, and X chromosomes carried the alike genes; they could mate and showed the crossover.
Properties controlled by these genes. Therefore, shows the same family distribution as autosomal characteristics (pseudo-autosomal inheritance). Gene specific for the Y chromosome is inherited "ustokket" through and to all men in a family, Y-chromosomal inheritance. Genes of the ca. 16 500 base pairs long DNA strand, mtDNA, in celleplasmaets mitochondria are inherited only through the ustokket women for all their children: mitochondrial or maternal inheritance. The significances of these findings are discussed in GENETIC EPIDEMIOLOGY. The table shows some examples of diseases that show simple inheritance. When the effect of either of two different plant wearing a pair of genes expressed in the observed properties, such as when certain blodtypinger or regulated at the protein analysis, talk of codominants (or intermediate) inheritance. There is also looking at properties that determine whether we call dominant or recessionary inheritance.
Inheritance systems behind it is not fundamentally distinctive, even if we have the bad habit of calling the genetic make dominant or recessionary. In many genes, we have now found many different mutations, some dominant and recessive-acting.