Features of multiple alleles. The same genes have more than two alleles. All multiple alleles in homologous chromosomes occupy the respective loci. A chromosome or gamete only has one group allele. Each human contains only two separate gene alleles, one for each homologous pair of chromosomes carrying the gene. More than two alternative alleles of a gene are known as multiple alleles in a population occupying the same locus on a chromosome or its homologue. ... Multiple alleles express various alternatives of one trait. Different alleles can exhibit codominance, dominance-recessive behaviour or incomplete dominance.

1. Rajendra Chavhan
NON-MENDELIAN INHERITANCE
PRESENTED BY
Dr. RAJENDRA CHAVHAN
Assistant Professor in Zoology,
Mahatma Gandhi Arts, Science &
Late N. P. Commerce College Armori, District Gadchiroli
MULTIPLE ALLELE

2. MULTIPLE ALLELE- Non-Mendelian Inheritance
Normally individual has two alleles.
About 30% of the Genes in humans are DI-ALLELIC, that is they exist in two forms,
(They have two alleles).
About 70% are MONO-ALLELIC, they only exist in one form and they show no variation.
A very few are POLY-ALLELIC having more than two forms.
Genes which have more than two alleles called Multiple allele.
During his study on Genetic, Mendel also assumed only two alleles of one trait.
There can be large number of possible allelic forms in that same
population. This situation is called as Multiple Allelism.
Multiple alleles always occupy the same locus on the chromosome.
Multiple alleles always influence the same character.
No crossing over among the member alleles of the same multiple
allelic series
More than TWO alleles exists for the trait

3. MULTIPLE ALLELE- Non-Mendelian Inheritance
This is very important to our immune system which
must tell the difference between our own cells (Self)
and invading disease causing microbes (Non-self)
Combinations:
Di-allelic genes can generate -------------3 genotypes.
Genes with 3 alleles can generate-------6 genotypes (3+2+1).
Genes with 4 alleles can generate-------10 genotypes
Genes with 8 alleles can generate-------36 genotypes
Genes and the immune system:
Poly-allelic alleles are usually associated with tissue types.
These provide genes are so varied that they provide us with our genetic
finger print.
More than TWO alleles exists for the trait

4. MULTIPLE ALLELE (Good examples)
Examples of Multiple Alleles
a) Blood Group (ABO) in human.
b) Coat colour in mice
c) Coat colour in rabbit
d) Eye colour in Drossophilla
More than TWO alleles exists for the trait

5. MULTIPLE ALLELE in ABO Blood Group
ABO Blood Group
Discovered by Karl Landsteiner in early 1900s.
An excellent example of multiple allele inheritance is human blood type.
Blood type exists as four possible phenotypes:- A, B, AB and O
There are 3 alleles (A, B & O) for the gene that determines blood type.
One combination of alleles in the ABO system exhibits a co-dominant mode of
inheritance which is blood type AB.
ABO blood group are controlled by the gene I.
More than TWO alleles exists for the trait

6. MULTIPLE ALLELE in ABO Blood Group
The ABO Blood system:
Classical and most common example of multiple allele is ABO blood group of human being.
This is a controlled by a tri-allelic gene.
Gene coding Blood group has three alleles rather than two.
It can generate 6 genotypes.
The alleles control the production of antigens on the surface of the red blood cells.
Two of the alleles are co-dominant to one another and both are dominant over the third.
More than TWO alleles exists for the trait

7. MULTIPLE ALLELE in Coat colour in Mice
 The coat colour or hair colour in mice is determine by a single gene
with a series of alleles.
 Alleles for black, brown, agouti, grey, albino and other colours of hair.
 These alleles follow order of dominance like AGOUTI > BLACK >
ALBINO.
 This means that agouti is dominant to black and albino; black is
dominant to albino.

8. MULTIPLE ALLELE in Coat colour in Mice
3 conclusions can be drawn:
1. All yellow mice carry the
Agouti gene.
2. Yellow allele is dominant to
agouti.
3. All surviving yellow mice
are heterogenous.

9. MULTIPLE ALLELE in Coat colour in Mice
Consider coat colour in Mice.
The presence or absence of colour is controlled by a number of alleles at one
gene locus.
Four alleles have been identified at this site:
C – Full colour expressed
Cch- chinchilla (silver points or flecks in the coat)
Ch-Himalayan or colour point (White coat with dark extremities)
C- Albino (no pigment present- white coat with pink eyes)
More than TWO alleles exists for the trait

10. MULTIPLE ALLELE - Coat colour in Rabbits
 Coat color in rabbits is inherited as a
series of multiple alleles.
 This means that there can be more
than just 2 alleles for a single gene.
 In the case of coat color in rabbits,
there are four alleles, and each one is
expressed with a different phenotype.
Could a mating between a light grey Rabbit and an Albino produce a Himalayan Rabbit ?
More than TWO alleles exists for the trait

11. MULTIPLE ALLELE - Coat colour in Rabbits
More than TWO alleles exists for the trait

12. MULTIPLE ALLELE - Coat colour in Rabbits
More than TWO alleles exists for the trait

13.  Normal eye colour in Drosophila is red. White eyed Drosophila was one of the first mutations
known in Drosophila. Red eye and white eye showed simple dominant recessive relationship.
MULTIPLE ALLELE - EYE colour in Drossophilla
 Multiple alleles for eye colour in Drossophilla and various
phenotypes due to homozygous and heterozygous conditions.
More than TWO alleles exists for the trait

14. MULTIPLE ALLELE - Coat colour in Rabbits
More than TWO alleles exists for the trait

15. Other genes with dominant alleles are:
The agouti gene-controls colour expression along the length of each shaft of hair.
The dilute genes, which also influence coat colour.
MULTIPLE ALLELE - Agouti
 Agouti: Hairs with more than one colour band on the hair shaft.
 Produce a ticked/agouti coat.
 Typical colour animals (mice, squirrels, rabbits, wolves etc.
 Thought important to crypticity (ability to blend into the
background)
 Determine by the dominant agouti
allele, A.
 Non-agouti cats are unbanded,
with a solid coloured coat, if
homozygous for the non-agouti
allele (aa) at the agouti locus.
 Though it looks ‘Brown’ it is
technically brown and black banded
fur.

16. How does it works ?
The agouti gene controls where and how brown and black pigments are set into hair.
Need to look at how colour is formed in mammal hair.
MULTIPLE ALLELES - Agouti
Melanocytes
At the base of each hair follicle is a melanocyte cell.
Produces pigment and inserts it into the growing hair.
Two types of Pigment
Melanocytes make two types of pigment.
Eumelanin (Brown and Blacks)
Phaeomelanin (Reds and Yellow)
Each relies on a series of pathways before it gets
to its final “Colour”

17. MULTIPLE ALLELES - Agouti
Tyrosine 5,6 dihydroxyindole Eumelanin

18. MULTIPLE ALLELES - TABBY
Tabby cats have:
 M on forehead.
 Thin pencil lines on face.
 Black “eyeliner” appearance and
white or pale fur around eyeliner.
 Pigmented lips and paws.
 A pink nose outlined in darker
pigment.
 Torso, leg and Tail banding. (Torso
banding not in the ticked tabby).

19. RNC