Question

Explain deviation from Mendel's model of the inheritance of traits(ie. his principles/theory of inheritance)  (.

please use the terms below in your answer)

Chi-square

Linked genes

map distance

Multiple alleles

Poly genic

Mitochondrial DNA

Maternal inheritance

Answer 1

Ans ) In 1902, Sutton and Boveri proposed the Chromosomal Theory of Inheritance it explains how cellular transmission or genetic dominants are passed from one generation to another

In 1850 Mendel formulated some of the fundamental principles concerning the mechanisms of hereditary. when two or more genes are located on the same chromosome they are said to be linked and their transmission is called linkage. all genes present on a particular chromosome form a linkage group. on the basis of this, we can also calculate the recombinant frequency

Genetic mapping:- The linkage of genes in chromosome can be represented in the form of a genetic map or linkage map or chromosomal map. Map distance can be calculated by:-

The unit of genetic linkage is centimorgan.

Similarly, if more than one gene determines the expression of a trait then it is said to be a polygenic inheritance

Characters that are governed by nonnuclear genes like mitochondria or chloroplast genes or endosymbiont .this phenomenon is called extranuclear or cytoplasmic inheritance. the characters are controlled by cytoplasmic genes and have certain characteristics:-

• lack of Mendelian segregation and typical mendelian ratios
• persistence of characters over several generations
• different phenotypes of progeny over reciprocal crosses

Cytoplasmic inheritance of trait is when carried from only one parent i.e. uniparental inheritance when only carried by mother is called maternal inheritance whereas in maternal effect the hereditary determinants are nuclear genes. carried by both sexes. The inheritance of streptomycin resistance in Chlamydomonas reinhardii and inheritance of striped leaves in maize is carried by chloroplast gene and show uniparental maternal inherirtance.