Pop Quiz Notes From September 14 Notes

Chapter 5
Give an example of a beta-lactam antibiotic. How do beta-lactam antibiotics kill bacteria?
Penicillian, amoxicillian and monobactin are all examples of beta-lactamn antibiotics. They attack the structure of the peptydoglycan cell wall to kill bacteria.

What is an "autolysin?" Why do bacteria make autolysins?
Autolysins are bacterial cytoplasmic membrane proteins that break down peptidoglycan. Autolysins give the bacterium some breathing room by breaching the cell wall, which is necessary for the cell wall to lengthen itself in order to divide.

Why aren't gram-negative bacteria killed by vancomysin?
Gram-negative bacteria aren't killed by vancomysin because vancomysin is too big to fit through the outer membrane to the plasmic space.

How have bacteria become resistant to beta-lactam antibiotics?
Bacteria have become resistant because they have mutation capabilities against the antibiotics that destroys the B-lactam. Making an enzyme that destroys penicillian is another way to defeat the antibiotics.

Are any gram-positive bacteria resistant to vancomysin? What might account for this resistance?
Some gram-positive bacteria may be naturally resistant to vancomycin because they hae peptides in their peptidglygan that do not have a terminal D-alanine-D-alanine peptide. Examples are bacteria in the lactobacillus species, such as unpastuerized yogurt.

Chapter 6
Name 2 drugs that block bacterial ribosomes. Why does stopping translation kill the cell, even it it's not dividing?
Streptomysin, Zythromax; Proteins do the work of the cell so if you can't produce proteins, you are a gonner!

Why doesn't Zithromax hurt human cells?
Zithromax can't kill human cells because our proteins are just a little different in the ribosomes so it doesn't affect our cells!

Why isn't tetracycline prescribed for pregnant women or young children in first-world countries?
Tetracycline affects the calcium deposits in the bones and teeth to discolor them to a nasty yellow color.

List 2 ways that bacteria can become resistant to antibiotics that stop protein synthesis.
Mutation and proteinsynthesis are 2 ways bacteria become resistant.

Chapter 7
How does rifampin work? What infection is it used to treat? Would rifampin kill archaea?
It inhibits the RNA prolymerase, or prevents mRNA from being transcribed. It is used to treat TB, bacterial meningitis. Rifampin would NOT be able kill archaea because archaea are closer to eukaryotic cells than prokaryotic bacteria cells.

Why does isoniazid kill tuberculosis bacteria but not gram-positive or gram-negative bacteria?
Isoniazid doesn't kill gram-positive or gram-negative bacteria because it is an acid-fast bacteria that has mycolic acid that in turn affects the integrity of the cell envelope to make the cell blow up.

What is the target of ciprofloxacin? Why does ciprofloxacin kill bacteria, even when they are not dividing?
Ciprofloxacin targets and binds to DNA gyrase so the bacteria can't unwind their DNA. (pg 87)

Chapter 10
What is the difference between an antiseptic and an anitbiotic?
Antibiotics are internally taken whereas antiseptics are more of a general weakener. An antiseptic targets EVERYTHING (fungus, virsus & protazoa) and destroys targets that ALL cells have.

What is the difference between an antiseptic and a disinfectant?
Antiseptics and disinfectants do the exact same thing, the difference is a matter of the concentration. Disinfectants have a high concentration, and are therefore stronger than antiseptics.

What cellular feature do halides destroys? Give an example of halide that is used as an antiseptic, and an example of a halide that is used as a disinfectant?
Halides destroy proteins and DNA. An antiseptic halide is iodine which is used to clean an area of skin before breakage or entry. A disinfectant halide example would be chlorine, used to clean pools. (pg. 131)

What cellular feature do alcohols destroy?
Alcohols destroy phospholipids in the cell membrane by dissolving them.

Give an example of an alkylating agent. Why do alkylating agents kill cells?
Formaldehyde. Alkylating agents kill cells by inactivating proteins, which a cell cannot function without.

Why do heavy metals kill cells? Give an example of a heavy metal used as an antiseptic.
Heavy metals kill cells because they denature (change the shape and thus the function) proteins. An example would be silver in catheter plastic.

Can bacteria ever become resistant to disinfectants?
Yes, bacteria have already become resistant to some antiseptics. But it's thought that bacteria will never able to become resistant to two disinfectants: alcohol and household bleach. (pg 135)

Why is resistance to antibiotics "easier" to evolve than resistance to disinfectants is?

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