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.

Biology & Microbiology

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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.

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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

Biology & Microbiology

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?

Biology & Microbiology

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

Biology & Microbiology