GENETICS AND EVOLUTION
GENETIC BASIS OF INHERITANCE
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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describes the genotype of a trait for which the two alleles an individual carries are the same
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an individual who carries one allele for a recessive trait and does not exhibit the trait.
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a trait controlled by a gene on a sex chromosome
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None of the above
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Detailed explanation-1: -A carrier, as related to genetics, is an individual who “carries” and can pass on to its offspring a genomic variant (allele) associated with a disease (or trait) that is inherited in an autosomal recessive or sex-linked manner, and who does not show symptoms of that disease (or features of that trait).
Detailed explanation-2: -Recessive alleles are only expressed if both of a person’s alleles are recessive. If a person has one dominant allele and one recessive, he is called a carrier. This is because he expresses the dominant trait, but “carries” the recessive trait. An example of this is albinism.
Detailed explanation-3: -An individual with one dominant and one recessive allele for a gene will have the dominant phenotype. They are generally considered “carriers” of the recessive allele: the recessive allele is there, but the recessive phenotype is not.
Detailed explanation-4: -Recessive inheritance means both genes in a pair must be abnormal to cause disease. People with only one defective gene in the pair are called carriers. These people are most often not affected with the condition. However, they can pass the abnormal gene to their children.
Detailed explanation-5: -A parent with a single disease allele has a probability of ½ of passing the allele to any one of its children. The probability that an individual is a carrier is a number between 0 and 1. If we know an unaffected individual must be a carrier, then the probability is 1 that the individual is a carrier.