[Campbell Biology P.361] How are genomic imprinting and inheritance of mitochondrial DNA exc... | Practice Question

How are genomic imprinting and inheritance of mitochondrial DNA exceptions to standard Mendelian inheritance?

  • A: In both cases, the sex of the parent contributing the allele affects the phenotype of the offspring.
  • B: In both cases, genes are passed down on the Y chromosome.
  • C: Both involve alterations in chromosome number.
  • D: Both are caused by crossing over between linked genes.

Explanation

The summary for Concept 15.5 highlights that in both cases, the parental origin of the allele matters. For genomic imprinting, the phenotype depends on whether an allele is inherited from the mother or father. For mitochondrial inheritance, the traits depend solely on the maternal parent because the organelles come from the egg's cytoplasm. This violates the Mendelian assumption that alleles have the same effect regardless of their parental source.