Asked in HEC Phase II 2017 2017Moderate

The condition in which one of more genes that have no allelic counterpart is known as:

Correct answer: B. Hemizygous

  • A. Homozygous
  • B. Hemizygous
  • C. Heterozygous
  • D. Incomplete dominance

Explanation

Hemizygous means having only a single copy of a gene instead of the customary two copies. All the genes on the single X chromosome in the male are hemizygous. Homozygous means having 2 identical alleles of a particular gene. Heterozygous means having 2 different alleles of a particular gene. Incomplete dominance is a form of Gene interaction in which both alleles of a gene at a locus are partially expressed, often resulting in an intermediate or different phenotype. The correct answer is, therefore, B.

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About X-linked Recessive Inheritance

X-linked recessive inheritance involves genes on the X chromosome, so males express a recessive allele with no corresponding allele on their single X chromosome, while females may be carriers. Pedigrees cover haemophilia and red-green colour blindness, including carrier mothers, affected sons and the absence of father-to-son transmission.

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