dihybrid inheritance linkage
Overview
This lesson explores dihybrid inheritance, the simultaneous inheritance of two different genes, and the concept of linkage, where genes located on the same chromosome are inherited together. Understanding these principles is crucial for predicting offspring phenotypes and genotypes in more complex genetic crosses. We will delve into Mendel's law of independent assortment and how linkage deviates from it.
Introduction to Dihybrid Inheritance
Dihybrid inheritance involves tracking the inheritance patterns of **two different genes simultaneously**. Each gene has at least two alleles, and these genes are typically located on different homologous chromosomes. A classic example is Mendel's pea plant experiments, where he studied seed color (...
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Key Concepts
- Dihybrid Cross: A genetic cross involving two different genes, each with two alleles.
- Independent Assortment: Mendel's second law stating that alleles for different genes segregate independently during gamete formation.
- Linkage: The tendency of genes located close together on the same chromosome to be inherited together.
- Recombinant Gametes: Gametes produced by crossing over between linked genes, resulting in new combinations of alleles.
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Exam Tips
- →Always draw out Punnett squares for dihybrid crosses, especially when dealing with independent assortment, to systematically determine gamete combinations and offspring genotypes/phenotypes.
- →When asked to identify linkage, look for deviations from the expected 9:3:3:1 (F2 dihybrid cross) or 1:1:1:1 (dihybrid test cross) ratios. A significantly higher proportion of parental phenotypes suggests linkage.
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