Cell Biology: The Cell's Built-In Self-Destruct Program
A tour of the cell, from membranes and mitochondria to division, death and the microscopes that reveal them.
Cell Biology · 50 questions
Try 3 questions
1. What do bacterial cells lack that human cells have?
- Ribosomes for making proteins
- A nucleus enclosing their DNA
- A membrane around the cell
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Answer: A nucleus enclosing their DNA
Prokaryotes keep their DNA in the cytoplasm; they do have ribosomes and a plasma membrane.
2. How does the number of bacteria living in and on your body compare with the number of your own cells?
- Under one percent as many
- About ten times more
- Roughly the same number
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Answer: Roughly the same number
Recent estimates put both at around 30 to 40 trillion, overturning the old 'ten to one' claim.
3. About how many times wider is a typical human cell than a typical bacterium?
- About a thousand times
- About the same
- About ten times
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Answer: About ten times
Bacteria are usually 1 to 2 micrometers across, while most human cells are 10 to 30 micrometers.
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