in this we'll discuss about mendelian inheritance that how Mendel worked. And why he called as the Father of Modern genetics.

2. Let’s Review

3. Mendelian Inheritance
Presented by
Aeman Adnan
M.Mubashir
Fatima Manzoor
Maryam Sadiq
Mubashir Hussain

4. “Introduction to Mendelian Inheritance"
• Gregor Mendel, an Austrian monk, is renowned for
his pioneering work in the field of genetics.
• Mendel's research, conducted in the mid-19th
century, laid the foundation for our modern understanding
of heredity.

5. Why Mendel choose Pea plant
• Pea plants were ideal for controlled breeding due to their easily
distinguishable traits.
• Mendel observed several traits including
Seed color (yellow or green)
Seed shape (round or wrinkled)
Flower color (purple or white)
Flower position ( axial or terminal)
Pod color (green or yellow)
Pod shape (inflated or constricted)
plant height (tall or short)
• He meticulously conducted controlled crosses, controlling which plants
were bred with each other.

6. Mendel's Discoveries:
• Mendel introduced the concept of dominant and
recessive alleles.
• Dominant alleles are expressed when present, while
recessive alleles are only expressed when two recessive
alleles are inherited.
• He identified specific ratios for trait inheritance, such as
the 3:1 ratio for dominant to recessive traits.
• Mendel's discoveries demonstrated that heredity follows
specific rules and can be predicted mathematically.

7. The Implications of Mendel's Work :
• Mendel's work has broad implications in genetics. In
agriculture, it underpins crop breeding by selecting for
desirable traits.
• In medicine, understanding Mendelian inheritance is
essential for studying genetic disorders and inherited
diseases.
• In evolutionary biology, Mendelian inheritance explains
how genetic diversity within species is maintained.

8. Mendelian Inheritance and Modern
Genetics:
• Mendel's legacy endures in modern genetics as
his laws continue to be a cornerstone of genetic
research.
• His meticulous approach to experimentation and
his foundational discoveries have shaped the field of
genetics for over a century.

9. Three laws of Hereditary
There are three laws proposed by Mendel
 Law of segregation
 Law of independent Assortment
 Law of Dominance

10. Law of Dominance
Definition
When two organisms homozygous pure for two different trait, their offspring hybrid is
heterozygous in which one allele suppress the effect of another allele.
The traits are controlled by two factors that can be called ‘’dominant’’ or ‘’recessive.’’
A ‘’dominant’’ trait that shows if the offspring inherits at least one dominant factor from one
Parent.
A ‘’recessive’’ trait that shows only if the offspring inherits two recessive factors, one from
each Parent.

11. Example
when pea plants with Yellow
color seeds (gg) are crossed
with plants with green color
seeds (GG), all seeds in F1
generation were found to be
round (Gg).
All seven traits studied by
Mendel.

12. Limitations
The law is not applicable for all living
organisms as it is only valid in the case
of diploid organisms and the organisms
that undergo sexual reproduction.

13. Principle
The law (or the principle) of dominance states
that the presence of a dominant allele will
always mask the presence of a recessive allele.
Complete dominance is a form of dominance in
the heterozygous condition wherein the allele
that is regarded as dominant completely masks
the effect of the allele that is recessive.

14. Law of Segregation
Also known as First law of inheritance.
It describes
How a alleles for a particular trait
segregate or separate during the
formation of gametes (sex cells:
sperms and egg) in sexually
reproducing Organisms

15. Example
Results
Purple is dominant over white
Phenotypic ratio of F2 generation is 3:1
Genotypic ratio of F2 generation is 1:2:1

16. Limitations
Law of segregation applies only to traits that completely
control a single gene pair in which one of the two alleles is
overriding the other. Therefore, the law of segregation does
not apply to incompletely dominant or co-dominant alleles.

17. Law of Independent Assortment
Introduction
 Law of independent assortment is stated that
When two contrasting pairs of traits are followed in the same cross, their alleles assort
Independently into gametes.
 The distribution of alleles of one trait into gametes has no influence on the distribution
Of alleles of the other trait.
 Law of independent assortment was developed by studying dihybrid cross.

18. Phenotypic and genotypic expression

19. Limitations
 Genes are located on chromosomes at specific loci.
Independent assortment of genes
depends upon independent assortment of their
chromosomes.
 All the genes present on a homologous pair of
chromosomes are linked to each other
in the form of a linkage group. These cannot assort
independently.
 Those traits assort independently whose alleles are
riding non homologous chromosomes

20. Exceptions of Mendelian Inheritance
Mendelian inheritance refers to the patterns of inheritance
described by Gregor Mendel, such as dominant and
recessive alleles. There are several exceptions to
Mendelian inheritance, including:
Incomplete dominance
Codominance

21. Incomplete Dominance
 Both alleles are expressed Partially
 Intermediate between both homozygotes
 Have different expressions e.g. R1 and R2
 Same Phenotypic and Genotypic Ratio
 No need of test cross
 Example:
Flower color in 4O’ clock plant

22. A cross between Red and white
flowered plants produced plants
with intermediate flower color e.g.
pink color
Ratio
1 : 2 : 1
Red: Pink: White
Example

23. Codominance
 Both alleles are expressed fully.
 Distinct from both homozygotes
 Different expression e.g. M and N
 Have same Phenotypic and genotypic Ratio
 No need of test cross.

24. Example

25. Conclusion
Why Mendelian Inheritance is important?
• Gregor Mendel's pioneering work with pea
plants provided us with the fundamental principles
of heredity.
• Understanding Mendelian inheritance is
essential for comprehending how traits are
passed from one generation to the next and how
genetic diversity is maintained.