When normal and mutant alleles are present on opposite chromosomes of homologous pair, the heterozygotes are called as

Options

A. cis heterozygote
B. homologous heterozygote
C. trans heterozygote
D. None of the above

Answer

To solve the question regarding the classification of heterozygotes when normal and mutant alleles are present on opposite chromosomes of a homologous pair, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Terms**:
- **Heterozygotes**: Individuals with two different alleles for a particular gene.
- **Normal Alleles**: Typically represented as uppercase letters (e.g., A, B).
- **Mutant Alleles**: Typically represented as lowercase letters (e.g., a, b).

2. **Identify Chromosome Arrangement**:
- In a homologous pair of chromosomes, one chromosome is inherited from the mother and the other from the father.
- The arrangement of alleles on these chromosomes can be in two configurations:
- **Cis Configuration**: Both normal alleles (A and B) are on one chromosome, and both mutant alleles (a and b) are on the other.
- **Trans Configuration**: One normal allele (A) is on one chromosome, and the other normal allele (B) is on the opposite chromosome, with the mutant alleles (a and b) also on opposite chromosomes.

3. **Determine the Configuration in the Question**:
- The question specifies that the normal and mutant alleles are present on opposite chromosomes. This indicates a trans configuration.

4. **Conclude the Type of Heterozygote**:
- Since the normal and mutant alleles are on opposite chromosomes, the heterozygotes are classified as **trans heterozygotes**.

### Final Answer:
When normal and mutant alleles are present on opposite chromosomes of a homologous pair, the heterozygotes are called **trans heterozygotes**.

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