Gene interaction is a broad term used to describe the joint role of multiple genes in determining phenotypic variability. It is often studied from the molecular point of view as biomolecular interactions or from a more genetic point of view as phenotypic effects due to the role of DNA sequence variations and their influence on biological processes. GENE INTERACTIONS: The phenomenon of two or more genes governing the development of a single character in such a way that they affect the expression of each other in various ways is known as gene interaction. When one gene affects in any way the expression of another gene, the phenomenon is called epistatis.

1. GENE INTERACTION
PRESENTED BY
Dr. RAJENDRA CHAVHAN
Assistant Professor in Zoology,
Mahatma Gandhi Arts, Science and
Late N. P. Commerce College Armori, District Gadchiroli
Rajendra Chavhan

2. Gene Interaction
DEFINITION: The phenomenon of two or more genes affecting the expression of each other in various ways in the development
of a single character of an organism is known as Gene interaction.
Most of the characters of living organisms are controlled/influenced/governed by a collaboration of several different genes.
MENDEL and others workers assumed that characters are governed by a single genes but later it was discovered that many
characters are governed by two or more genes.
Such GENES affect the development of concerned characters in various ways, this lead to the modification of the typical
dihybrid ratio (9:3:3:1) or trihybrid (27:9:9:9:3:3:1).
GENES are segments of DNA that code for particular polypeptide in the form of a specific
sequence of it’s base pair.
PROTEINS are the end products of gene expression, and so gene interactions are
interactions between proteins are interactions between proteins that are controlled by
these genes.

3. Gene Interaction
Mendel and subsequent workers assumed that a character was governed by a single gene.
But it was later discovered that many characters in almost all the organisms are governed by two or more genes.
Such gene affect the development of concerned characters in various ways.
The phenomenon of two or more gene affecting the expression of each other in various ways in the development
of a single character of on organism is known as GENE INTERACTION.

4.  Non-Mendelian inheritance is any pattern of inheritance in which traits do not segregate in accordance
with Mendel's laws.
Gene Interaction
 If the genotypes of both parents in a genetic cross are known, Mendel's laws can be used to determine the
distribution of phenotypes expected for the population of offspring.
 There are several situations in which the proportions of phenotypes
observed in the progeny do not match the predicted values.
 These laws describe the inheritance of traits linked to single genes on chromosomes in the nucleus.
 In Mendelian inheritance, each parent contributes one of two possible alleles for a trait.

5.  Mendelian inheritance patterns involve genes that directly influence the outcome of an
organism’s traits and obey Mendel’s laws.
 Most genes in eukaryotic species follow a Mendelian pattern of inheritance. However,
there are many that do not.
 Non-Mendelian inheritance is a general term that refers to any pattern of inheritance in
which traits do not segregate in accordance with Mendel’s laws.
 These laws describe the inheritance of traits linked to
single genes on chromosomes in the nucleus.
Gene Interaction

6. TYPES OF INTERACTION OF GENE
Gene interaction are classified as fallows on the basis of the manner in which the concerned gene influence the
expression gene action.
a) Allelic Gene interaction/Intra allelic interaction b) Non-Allelic Gene interaction/Inter allelic interaction

7. EXAMPLES OF INTERACTION OF GENE

8. Differences between
Allelic & Non allelic gene interaction
Allelic interactions/intra genetic interactions
 Alleles of the same gene interact in such
a way to produce new Characters.
For example
a) Complete Dominance
b) Incomplete Dominance
c) Co dominance or Blending inheritance
d) Cumulative Genes or Multiple Genes
e) Pleiotropism
Non-Allelic gene interaction/inter allelic genetic interactions
 The independent (non homologous) genes located on the same
or on different chromosomes interact with one another for the
expression of single phenotypic trait of an organism. This was
revealed by Modern Mendelian ratios.
 There are four types, they are as follows. (Action of these factor
may)
1. Complementary gene action
2. Inhibiting gene action (Epistasis)
a) Dominant Epistasis
b) Recessive Epistasis
3. Duplicating Factor
4. Supplementary factor
(Modifying Genes etc.)

9. Rajendra Chavhan