What are the genotypic and phenotypic expectancies for a cross between
heterozygous and homozygous recessive individuals?

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What are the genotypic and phenotypic expectancies for a cross between heterozygous and homozygous recessive individuals?

UpStudy AI · Accepted Answer

1. Let the heterozygous genotype be $$ Aa $$ and the homozygous recessive genotype be $$ aa $$.

2. The gametes produced by the heterozygous individual ($$ Aa $$) are $$ A $$ and $$ a $$, each with a probability of $$\frac{1}{2}$$. The homozygous recessive individual ($$ aa $$) produces only the $$ a $$ gamete.

3. Set up the Punnett square:

|         | $$ a $$      |
   |---------|--------------|
   | **$$ A $$** | $$ Aa $$     |
   | **$$ a $$** | $$ aa $$     |
   
4. **Genotypic Expectation:**
   
   - $$ Aa $$: $$\frac{1}{2}$$ of the offspring.
   - $$ aa $$: $$\frac{1}{2}$$ of the offspring.

5. **Phenotypic Expectation:**

Assuming that the allele $$ A $$ is completely dominant over $$ a $$:
   
   - The $$ Aa $$ offspring will show the dominant phenotype.
   - The $$ aa $$ offspring will show the recessive phenotype.
   
   Therefore:
   
   - Dominant phenotype: $$\frac{1}{2}$$ of the offspring.
   - Recessive phenotype: $$\frac{1}{2}$$ of the offspring.
- **Genotypic Expectation:** - $$ Aa $$: 50% - $$ aa $$: 50% - **Phenotypic Expectation:** - Dominant phenotype: 50% - Recessive phenotype: 50%

What are the genotypic and phenotypic expectancies for a cross between
heterozygous and homozygous recessive individuals?

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