Patterns of sex-linked transmission Transmission of a gene from a male parent to his daughter and then to his grandson (through the daughter) is termed what?

Difficulty: Easy

Correct Answer: Criss-cross inheritance

Explanation:


Introduction / Context:
Sex-linked traits often display characteristic transmission patterns across generations. Recognizing these patterns allows quick identification of X-linked recessive or dominant inheritance in pedigrees.



Given Data / Assumptions:

  • Male → daughter → daughter’s son transmission is described.
  • Sex chromosomes: males are XY, females XX.
  • No statement contradicts viability or dominance; the focus is the path of transmission.


Concept / Approach:
Criss-cross inheritance is typical for X-linked traits: a father passes his X chromosome to all daughters (never to sons). A daughter can then pass that X allele to her sons, producing the “male → daughter → grandson” path. Holandric inheritance is Y-linked (father to all sons), which does not match the pattern here.



Step-by-Step Solution:

Track the male’s X-linked allele → transmitted to the daughter (who is XX).Daughter passes that X to half of her sons (grandsons of the original male).This alternating sex transmission is termed criss-cross inheritance.


Verification / Alternative check:
Pedigree analysis examples of hemophilia or color blindness demonstrate this pattern repeatedly.



Why Other Options Are Wrong:

  • Holandric: Y-linked goes father → son only.
  • Quantitative: polygenic traits; not a transmission path term.
  • Maternal inheritance: mitochondrial/cytoplasmic, passed from mothers to all offspring.
  • Autosomal dominant: does not impose the sex-specific path described.


Common Pitfalls:
Assuming all sex-linked traits are father-to-son; X-linked cannot go father-to-son because fathers pass Y to sons.



Final Answer:
Criss-cross inheritance

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