Staphylococcus aureus is a gram-positive organism that produces the enzyme ?-lactamase, which renders certain types of antibiotics inactive. The mode of action that is prevented in certain antibiotics sensitive to this enzyme is:
a. cell wall synthesis.
b. protein synthesis to the 30S ribosomal subunit.
c. protein synthesis to the 50S ribosomal subunit.
d. deoxyribonucleic acid (DNA) synthesis.
A
?-Lactamases open the ?-lactam ring of the drug, and the altered structure prohibits subsequent effective binding to penicillin-binding proteins (PBPs), enabling cell wall synthesis to continue.
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The transposon "sleeping beauty" is:
A. a transposon from fish that was reactivated by mutation. B. a transposon from fish that was reactivated by introducing a plasmid that had a functional transposase. C. an artificially constructed transposon based on sequence comparisons of numerous inactive Tc1/mariner transposons. D. a retrotransposon of humans. E. a complex transposon that can move from cell to cell.
A candy bar contains 108 calories per serving. There are 4 grams of carbohydrate, 5 grams of protein, and 8 grams of fat in a serving. How many of the calories come from fat? Note: One food calorie equals one kilocalorie.
A. 72 B. 16 C. 18 D. 20
It is often said that development is a two-step process. Which two steps are likely to be referred to here?
What will be an ideal response?
Insect workers propagate more of their own alleles by helping their mother reproduce rather than by reproducing themselves; thus, they share a larger fraction of their ___________ with the next generation.
A. food resources B. time C. genome D. ability to defend their nest E. home