A patient presents to the emergency room with high fever, labored breathing, body aches and fatigue. The physician takes nasal swabs and sends them for testing. He suspects a viral infection. The infectious agent is probably a virus instead of a bacterium if it:
A. lacks membrane-bound organelles
B. cannot reproduce in acellular culture
C. has a length of 1μm, about the size of a mitochondrion
D. contains DNA
Click for Explanation
Viruses possess DNA or RNA but not both, require a host cell’s reproductive machinery in order to reproduce, and have a size 10-100nm. For the MCAT: eukaryotic cell > bacterium (roughly size of mitochondrion) > virion (roughly size of protein, roughly 100x smaller than bacterium, 1000x smaller than eukaryotic cell, cannot be seen with optical microscope).
A. lacks membrane-bound organelles, incorrect, Both viruses and bacteria lack membrane-bound organelles.
B. cannot reproduce in acellular culture, correct. Viruses require host cells in order to reproduce.
C. has a length of 1μm, about the size of a mitochondrion, incorrect, This is the size of a bacterium.
D. contains DNA, incorrect, Both bacteria and viruses may contain DNA.
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