Multifactorial_Inheritance_Presentation.pptx

Extensions to Mendel for
Multifactorial Inheritance
• A deep dive into complex inheritance patterns

Introduction
• Understanding how multiple genes and
environmental factors influence traits.

Mendelian Inheritance
• Basic principles: Dominant, recessive, and
independent assortment.

Beyond Mendel
• Traits that do not follow simple Mendelian
ratios.

Multifactorial Inheritance
• Traits influenced by multiple genes and
environmental factors.

Polygenic Inheritance
• Many genes contribute to a single trait, such
as height or skin color.

Gene Interactions
• Epistasis, complementary genes, and
modifying genes.

One-Gene Inheritance
• A single gene determines the trait (e.g., cystic
fibrosis).

Two-Gene Inheritance
• Two genes interact to produce a phenotype
(e.g., eye color).

Multiple-Gene Inheritance
• More than two genes contribute to the final
phenotype.

Environmental Influence
• How diet, climate, and lifestyle affect gene
expression.

Continuous vs. Discontinuous Traits
• Differences in phenotype expression.

Polygenic Traits
• Traits that show continuous variation, like
intelligence and weight.

Epistasis
• One gene affects the expression of another
gene.

Complementary Gene Action
• Two genes working together to produce a
trait.

Modifier Genes
• Genes that enhance or suppress other genes'
effects.

Threshold Traits
• Traits expressed only when a genetic liability
threshold is crossed.

Examples of Multifactorial Traits
• Diabetes, heart disease, schizophrenia, and
hypertension.

Case Study: Human Height
• Polygenic and influenced by environment.

Case Study: Skin Color
• Controlled by multiple genes and
environmental exposure.

Human Eye Color
• A classic example of polygenic inheritance.

Fingerprint Patterns
• Determined by genetics and prenatal
conditions.

The Bell Curve
• Distribution of polygenic traits in a population.

Twin Studies
• Nature vs. nurture in multifactorial
inheritance.

Genome-Wide Association Studies
(GWAS)
• Identifying genes contributing to complex
traits.

Heritability
• Measuring genetic vs. environmental
influence.

Genetic Risk Factors
• Understanding susceptibility to diseases.

Epigenetics
• How environmental factors modify gene
expression.

Multifactorial Diseases
• Heart disease, diabetes, cancer, and mental
disorders.

Genetic Counseling
• Assessing risk and inheritance patterns in
families.

Ethical Considerations
• Privacy, genetic testing, and personalized
medicine.

Future Research Directions
• Advancements in genetics and biotechnology.

Final Thoughts
• Mendel laid the foundation, but genetics is
much more complex.

Comparison: One-Gene vs. Two-
Gene vs. Multiple-Gene
Inheritance
Feature One-Gene
Inheritance
Two-Gene
Inheritance
Multiple-Gene
Inheritance
Gene Involvement Single gene
determines the trait
Two genes interact Several genes
contribute
Trait Type Simple Mendelian
traits
Intermediate
complexity
Complex traits with
continuous
variation
Examples Cystic fibrosis, sickle
cell anemia
Eye color, coat color
in animals
Height, skin color,
intelligence

Multifactorial_Inheritance_Presentation.pptx

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