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Textbook Question
Among Betazoids in the world of Star Trek®, the ability to read minds is under the control of a gene called mindreader (abbreviated mr). Most Betazoids can read minds, but rare recessive mutations in the mr gene result in two alternative phenotypes: delayed-receivers and insensitives. Delayed-receivers have some mind-reading ability but perform the task much more slowly than normal Betazoids. Insensitives cannot read minds at all. Betazoid genes do not have introns, so the gene only contains coding DNA. It is 3332 nucleotides in length, and Betazoids use a four-letter genetic code.
The following table shows some data from five unrelated mr mutations.
Mutation Description of Mutation Phenotype _
mr-1 Nonsense mutation in codon 829 Delayed-receiver
mr-2 Missense mutation in codon 52 Delayed-receiver
mr-3 Deletion of nucleotides 83–150 Delayed-receiver
mr-4 Missense mutation in codon 192 Insensitive
mr-5 Deletion of nucleotides 83–93 Insensitive
For each mutation, provide a plausible explanation for why it gives rise to its associated phenotype and not to the other phenotype. For example, hypothesize why the mr-1 nonsense mutation in codon 829 gives rise to the milder delayed-receiver phenotype rather than the more severe insensitive phenotype. Then repeat this type of analysis for the other mutations. (More than one explanation is possible, so be creative within plausible bounds!)
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