Why is Staphylococcus aureus often described as an international picnic pest?
What will be an ideal response?
Answer: S. aureus is a member of at least 20-30% of people's normal flora, so it is easily transmitted to foods, where it is capable of growth on several different foods. The pathogen grows very well at room temperature or slightly warm outdoor temperatures. Staphylococcal food poisoning is not caused by the bacterium but by the enterotoxin it produces during growth, which means the food could have been heated, and the heat-tolerant enterotoxins could have survived. Mayonnaise-based salads as well as custard- and cream-filled desserts are among the most common foods associated with staphylococcal food poisoning.
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A billionaire buys a sterile volcanic island that recently emerged from the sea. To speed the arrival of conditions necessary for plant growth, the billionaire might be advised to aerially sow what over the island?
A) basidiospores B) spores of ectomycorrhizae C) soredia D) yeasts E) leaves (as food for fungus-farming ants)
Viruses that attack bacteria are called
A. phages B. proviruses C. virulent D. lytic
You can use Hardy-Weinberg to calculate allele frequencies, but not genotype frequencies. (Hardy-Weinberg can be used to convert genotype frequency into allele frequency, and vice versa.)
A. true B. false
Suppose that an error in transcription alters the formation of a single tRNA molecule in a cell. The altered tRNA still attaches to the same amino acid (Phe), but its anticodon loop has the sequence AAU, which binds to the mRNA codon UUA (usually specifying leucine, Leu). What will be the effect on translation in this cell?
A. One altered tRNA molecule will be relatively inconsequential because it will compete with many "normal" ones. B. The altered tRNA will result in an amino acid variant in all copies of the protein. C. The altered tRNA will be so unstable that it will not participate in translation. D. The altered tRNA will cause this mRNA to make only nonfunctioning product. E. The tRNA-Leu will not be able to enter the ribosome to bind to the UUA codon.