Question

4. Complete the following table regarding rules of inheritance that are not Mendelian. Codominance Pleiotropy Incomplete dominance Polygenic inheritance Epigenetic inheritance Characteristics Example

Answer 1

	Incomplete dominance	co-dominance	pleiotropy	polygenic inheritance	Epigenetic inheritance
Characteristics	Here dominant allele expresses partially so not able to suppress recessive allele completely .Therefore intermediate traits are expressed in F1 generation .	Here both alleles involved show equal dominance or expression .None is dominant over another . So traits of both alleles expressed in F1 generation .	In pleiotropy single Gene regulates more than one characters .	In polygenic inheritance a single phenotype is controlled by involvement of many genes . Phenotype is sum of effect of genes involved . It is quantitative in nature .	In this pattern traits are affected not by change in DNA sequence but by other modifications in chromosome like histone acetylation , deacetylation , DNA methylation . This does not change sequence of codons but alters physical structure of DNA . It is different from general mendelian inheritance .
Examples	R allele for Red color flower is incompletely dominant over r allele in Snapdragon or Antirrhinum plant . So F1 shows pink color .	Blood group alleles i​​​​​A and i​​​​​​B​​​​​iB are codominant to each other in blood group AB and both alleles dominate over third allele i.	In Sickle cell anaemia allele HBs affect many organs by causing damage to them like pancreas, heart , brain as sickled RBC clog capillaries in major organs . Another example is CFTR Gene in Cystic fibrosis	Best example is our skin color which involves genes A, a, B,b, C,c . Other examples are eye color , height , intelligence etc .	One example from humans is gestational diabetes which can affect both mother and her daughter when she too becomes pregnant in future . Another example kink in tail of one of two genetically identical mice due chromosomal modification .