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?

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1. **Define the parents' genotypes:**

- Heterozygous: $$ Aa $$
   - Homozygous recessive: $$ aa $$

2. **Determine the gametes produced by each parent:**

- The heterozygous parent ($$ Aa $$) produces two types of gametes: $$ A $$ and $$ a $$ (each with a probability of $$\frac{1}{2}$$).
   - The homozygous recessive parent ($$ aa $$) produces only one type of gamete: $$ a $$.

3. **Set up the Punnett square:**

$$
   \begin{array}{c|cc}
      & A & a \
   \hline
   a & Aa & aa \
   a & Aa & aa \
   \end{array}
   $$

4. **Determine the genotypes of the offspring:**

- $$ Aa $$: Occurs in 2 out of 4 cases ($$50\%$$).
   - $$ aa $$: Occurs in 2 out of 4 cases ($$50\%$$).
   
   **Genotypic ratio:** $$ 1:1 $$ or $$50\%$$ $$ Aa $$ and $$50\%$$ $$ aa $$.

5. **Determine the phenotypes:**

Assuming that $$ A $$ is dominant over $$ a $$:
   
   - $$ Aa $$ individuals express the dominant phenotype.
   - $$ aa $$ individuals express the recessive phenotype.
   
   **Phenotypic ratio:** $$50\%$$ dominant phenotype and $$50\%$$ recessive phenotype.
- **Genotypes:** 50% $$ Aa $$ and 50% $$ aa $$ - **Phenotypes:** 50% dominant and 50% recessive

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

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