Genes and alleles Transitional Reasoning Download PDF

Questions

1. 1.

   A geneticist investigates a diploid plant and analyzes a specific locus on homologous chromosome pair 4 that influences trichome morphology. Molecular sequencing reveals that the DNA sequence on the maternal chromosome codes for a functional branching protein, whereas the sequence at the identical position on the paternal chromosome contains a single nucleotide substitution yielding an inactive protein. Based on this observation, which statement correctly identifies the relationship between these two DNA sequences?

   • A) The two sequences represent two distinct, non-allelic genes that occupy separate loci on different chromosomes.
   • B) The paternal sequence represents a structural chromosomal mutation, whereas only the maternal sequence constitutes a true gene.
   • C) The maternal and paternal sequences represent two different alleles of the same gene, occupying the same locus on homologous chromosomes.
   • D) The matching chromosomal positions indicate that both sequences are identical alleles, as alleles cannot differ in nucleotide sequence.