mendels's law of inheritance presented by :Muneeb Qadir lone M.pharm i;Ist yr Department of pharmaceutical sciences,University of Kashmir

1. Mendel’s laws
of
inheritance
presented by:
Muneeb qadir lone
M.Pharm 1st yr
BRANCH:Pharmacognosy
Department of pharmaceutical sciences,university of kashm

2. GREGOR JOHANN MENDEL
• 1822-1884
• Austrian monk
• Principles of genetics were developed in the mid 19th century
• Gregor Mendel is the father of modern genetics

3. Mendel’s experiment
• Experiment was performed in 3 stages;
• Selection of true breeding plant(parent)
• He selected 7 pairs of true breeding variety of pea
plant .On self pollination true breeding variety give
same traits
• Hybridization of f1 generation
• Mendel performed reciprocal cross between plants
with contrast trait.Performed various
mono/dihybrid cross

4. .Self pollination between f2,f3 generations
.f2 generation offsprings obtained from f1,self pollinated
then again cycle continued.

5. Contrasting traits studied by mendel in pea
plant;

6. D0minant and recessive factor;
Dominant factor
• it is able to express in both
homo & heterozygous
condition.
• It can produce complete
polypeptide or enzyme for
expressing effect.
Recessive factor
Expresses itself in
homozygous condition.
It forms
incomplete/defective protein
chain.

7. Homozygous & heterozygous condition;
Homozygous [same allele]
• It is pure for a trait & give
rise to similar homozygous
individual.
• They posses either
dominant or recessive
allele.
• Only one type of gamete
produced.
• Hybrid vigour is absent.
Heterozygous [diff allele]
• Not pure for a trait produce
different allele.
• They posses both one
dominant and one
recessive allele.
• Different type of gamete
produced.
• Hybrid vigour present.

8. Monohybrid cross;
• When we consider the inheritance of one character at a time in
a cross.
• pure yellow and pure green.
• Phenotype ratio 3:1
• Genotype ratio 1:2:1

9. Dihybrid cross;
• A cross in which we study the inheritance of two characters
simultaneously.Mendel wanted to observe the effect of one pair of
allele on other pair in heterozygous organisms.

10. Back cross:
• When a f1 generation is crossed with either of 2 parents.
• Outcross;when an individual is crossed with dominant
parent.generation obtained from this cross,all posses
dominant character.
• Test cross:the progeny is crossed with recessive parent.

11. Reciprocal cross :
• Sex of parent is reversed.
• Characters controlled by karyogenes are not affected .
• Test cross:
.When f1 progeny is crossed with recessive parent .
.in test cross phenotypic and genotypic ratio are same.
.test cross helps to find out genotype of dominant phenotypic
individual.

12. Law of dominance;
• Characters are controlled by discreate units called factors.
• Factors occur in pairs .
• In a dissimilar pair of factor one member dominates over other and
other one is recessive .
• Law of dominance explains expression of only one of parenteral
character in monohybrid cross in f1 generation & expression of both
in f2 .
• It also explains proportion of 3:1 obtained in f2 generation.

13. Law of segregation:
• This is based on fact that allele don’t show blending &both traits are
recovered as such in f2,though one of this is not seen in f1 stage.
• The parents contain 2 alleles during gamete formation ,the factor or
allele of a pair segregate from eachother such that one gamete
receive only one of two factors.
• Segregation is essential during meiotic division in all sexually
reproducing animal.
• No exception to this law (non disjunction may be exception to this
law).

14. Law of independent assortment:
• When 2 pair of traits (2 characters)are combined in a hybrid
,segregation of one pair of characters is independent of other pair of
characters.
• This law is applicable to only those factors or genes which either
located distantly on same chromosome or occur in different
chromosome.
• There are 4 types of gametes formed RY , rY , Ry , ry with a frequency
of 25%of total gametes produced.

15. Applications of mendel’s law
• Using the mendels’s law,we can produce new
combinations in the progeny of hybrids and can predict
their freguency.
• This information is vastly used by plant and animal
breeders to produce better breeders.
• New type of plants with new combinations of usefull
chararacters can be produced by hybridization .

16. Thank you