Rucete ✏ Biology In a Nutshell
1. What Is Intermediate Inheritance?
- Intermediate inheritance refers to genetic situations where neither allele is completely dominant.
- Two main types: Incomplete dominance and codominance.
2. Incomplete Dominance
- In incomplete dominance, the heterozygous phenotype is a blend of the two homozygous phenotypes.
- Neither allele is fully dominant, so both contribute partially to the trait.
Example: Snapdragons
- Red flowers: RR
- White flowers: rr
- Heterozygous: Rr → Pink flowers
- Resulting phenotype is intermediate (pink), not fully red or white.
3. Codominance
- In codominance, both alleles in a heterozygote are fully expressed—not blended.
- The result is a phenotype where both traits show up simultaneously.
Example: MN Blood Type
- M allele + N allele = MN blood type
- Both M and N proteins are expressed on the red blood cells.
- Genotypes:
- MM → M type
- NN → N type
- MN → Both M and N proteins visible (codominant expression)
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Biology in a nutshell