Focus on genetic inheritance patterns that do not follow Mendel's principles.
Key Concepts
1. Non-Mendelian Inheritance
Definition: Genetic inheritance patterns that do not adhere to Mendel's laws.
Examples include:
Incomplete Dominance: A situation where the phenotype of heterozygotes is intermediate between the phenotypes of individuals homozygous for either allele.
Codominance: Both alleles are fully expressed in the heterozygous condition.
Multiple Alleles: More than two alleles exist for a particular gene.
Polygenic Inheritance: Traits that are controlled by more than one gene.
2. Incomplete Dominance
Example: Snapdragons, where red and white flowers produce pink offspring.
Significance: Shows blending of traits.
3. Codominance
Example: AB blood type in humans where both A and B antigens are expressed.
Significance: Demonstrates simultaneous expression of both alleles.
4. Multiple Alleles
Example: ABO blood group system.
Explanation: Existence of more than two allele forms within a population.
5. Polygenic Inheritance
Traits influenced by multiple genes, resulting in continuous variation.
Example: Human skin color, height.
Implications of Non-Mendelian Inheritance
Greater genetic diversity within populations.
Complex patterns of inheritance that contribute to phenotypic variation.
Impact on genetic counseling and understanding hereditary diseases.
Conclusion
Non-Mendelian genetics broadens the understanding of inheritance beyond simple dominant-recessive relationships.
Essential for understanding complex genetic traits and variations.