Safe hits and escaping germs

Science · Microbiology · ages 21-22

Name ______________________ Date ____________

A drug garbles translation on the bacterial ribosome. Why is that selective?
- The bacterial ribosome differs from yours
- Human cells contain no proteins at all
- Ribosomes exist only during infection
Why do beta-lactams kill bacteria but leave your cells alone?
- Your cells pump out every drug instantly
- Your cells lack all ribosomes
- Your cells build no peptidoglycan wall
Selective toxicity means harming the microbe while sparing the host.
Circle one: True False
A pathogen loses the porin that a drug uses to enter. Which road is this?
- Destroying the drug
- Overproducing the target
- Barring entry
A microbe snips the beta-lactam ring of penicillin. Which road is this?
- Pumping the drug out
- Destroying the drug
- Reworking the target
Why does a broad-spectrum drug risk a superinfection?
- It kills the protective residents, freeing room for a resistant squatter
- It makes every virus stronger
- It stops the immune system from learning
A lab finds one pump that ejects three unrelated drug classes. What does this show about resistance?
- Each drug needs its own unique pump
- Pumps only work on viruses
- One mechanism can defeat several drugs at once
A student stops pills early because they feel better, saying the rest is pointless. What is the flaw?
- The drug needs months to enter the blood at all
- Stopping early spares the hardiest survivors, which then inherit the site
- Leftover pills always poison the liver

Answer key

For grown-ups. Fold this page away before handing over the rest.

The bacterial ribosome differs from yours · The structural gap between ribosomes lets the drug hit one and spare the other.
Your cells build no peptidoglycan wall · No wall means no target, so the drug passes your cells by.
True · The wider the biological gap aimed at, the safer the drug.
Barring entry · Fewer entry pores keep the drug below killing levels inside the cell.
Destroying the drug · Beta-lactamase enzymes hydrolyse the ring, and the broken drug goes quiet.
It kills the protective residents, freeing room for a resistant squatter · Clearing the normal guard lets a resistant pathogen bloom into a second infection.
One mechanism can defeat several drugs at once · A single efflux pump can translocate multiple drug types, giving cross-resistance.
Stopping early spares the hardiest survivors, which then inherit the site · Selection logic says quit while the toughest are alive, and they become the new population.