Among Betazoids in the world of Star Trek the ability to rea

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 Deletion of nucleotides 83-150 Delayed-receiver mr-3 mr-4 Missense mutation in codon 192 Insensitive mr-5 Deletion of nucleotides 83-93 Insensitive Pearson Education Inc,

Solution

1. The mr-3 mutation is a deletion that produces a protein that is 17 amino acids shorter than normal. It does not cause a frameshift.

2. The mr-4 mutation changes a single amino acid, disrupting a critical region of the protein.

3. The mr-1 mutation would terminate translation prematurely. The mutant protein is missing 4 amino acids at the carboxyl end.

4. The mr-5 mutation is a deletion that causes a frameshift. Most or all of the amino acids downstream are changed.

5. The mr-2 mutation changes a single amino acid that is not critical for protein function.