GTC BIO 2117 Test 4 Review Questions
And Detailed Answers.
What do we call antibiotics that kill gram negative and gram positive bacteria? - Answer Broad
spectrum drugs (antibiotics) are effective against both gram negative and gram positive
bacteria.
What do we call it when we give the patient 2 or 3 different antibiotics a once? Why would we
do that? - Answer Combination chemotherapy. Pathogens are capable of becoming resistant
to a single agent, but combination chemotherapy (using more than one drug) makes it more
difficult for the pathogen to develop resistance.
What is chemotherapeutic index? - Answer The relationship between toxicity of a compound
for the body and the toxicity for parasites.
If a drug has a low chemotherapeutic index, what does that mean? Is that good or bad? -
Answer Drugs that have a low chemotherapeutic index often inhibit pathways or attack
structures found in the host cells. For example, cancer cells closely resemble normal body cells,
therefore, it is difficult to poison the cancer cells without poisoning the body. A low
chemotherapeutic is bad. The larger the therapeutic index, the better the chemotherapeutic
agent, and the less toxic it is to the host. Drugs often have high therapeutic indexes if the target
of the drug is a structure or pathway not found in the host organism.
A drug has a low selective toxicity. Is that a good or bad thing? - Answer Selective toxicity is
the ability of a chemical or drug to kill a microorganism without harming its host, therefore, a
low selective toxicity is a bad thing.
Name four major methods by which antibiotics work: - Answer 1) inhibit cell wall synthesis
2) inhibit protein synthesis
3) inhibitor of nucleic acid synthesis
4) inhibit folic acid synthesis
Penicillin is made by a ______? - Answer fungus (mold/penicillium)
Who discovered penicillin? - Answer Fleming
,What are three problems with penicillin? - Answer 1) overuse has led to resistance. Many
bacteria have beta-lactamase (penicillinase), an enzyme which inactivates the penicillin.
2) narrow spectrum
3) anaphylactic reaction: many people allergic
What types of microorganisms are affected by pencillin? - Answer primarily for staph and strep
infections- also syphilis
What do we mean by semisynthetic penicillin? Are they only good for gram positive
microorganisms? - Answer Altered natural beta-lactams create semisynthetic derivatives of
penicillin. These are synthetic and more expensive. They have a broader spectrum than
penicillin due to their modified chemical structures.
Why do they add clavulinic acid to penicillin? - Answer The clavulinic acid inactivates the
penicillinase made by bacteria.
What is beta-lactamase? - Answer A bacterial enzyme that catalyzes the hydrolysis of the
lactam ring in some penicillin antibiotics, rendering them ineffective. Beta-lactamase is also
known as penicillinase.
Cephalosporins are described as first generation, second generation, and third generation. What
is the difference? - Answer first generation are generally used for gram positives. They are
narrow spectrum. second generation are more broad. They kill enterics (gram - and some gram
+). Third generation kills pseudomonas and is broad spectrum killing gram - and even more
gram +.
How do these work? - Answer They work like penicillin by inhibiting cell wall synthesis. They
do this by inhibiting the cross linkages between the NAM and NAG layers of the peptidoglycan
cell wall. The cephalosporins are resistant to beta lactamase enzyme.
Why are these drugs better for some people than penicillin? - Answer They are active against
more organisms and do not cause as many allergic reactions as penicillin.
Name four drugs other than penicillin that inhibit the synthesis of the cell wall: - Answer ABI V.
1. Augmentin
2. Bacitracin
, Which of these drugs is for topical application? - Answer bacitracin
Name 2 drugs that inhibit mycolic acid production/cell wall synthesis in Mycobacteria: - Answer
isoniazid and ethambutol
Why can we give drugs that disrupt ribosomes? Wouldn't that also affect human ribosomes? -
Answer The drugs only affect the 30s ribosomes in prokaryotic cells. Human cells are not
affected because they have 40s ribosomes since they are eukaryotic.
Aminoglycosides are effective against gram _____ bacteria - Answer negative
What are some side effects of aminoglycosides? - Answer 1. hearing loss
2. kidney damage
Tetracycline is considered a ______________ _____________ antibiotic. - Answer broad
spectrum
Tetracycline is effective against intracellular bacteria such as: - Answer chlamydia and rickettsia
Tetracycline is effective against bacteria without a cell wall such as: - Answer mycoplasma
What is the problem with tetracycline and children? - Answer discolors teeth and affects bone.
What drug gets through the blood brain barrier and is great for treating meningitis. (also treats
rickettsia and chlamydia)? - Answer chloramphenicol
Problem associated with chloramphenicol - Answer toxicity in children--> aplastic anemia. This
is very serious as it causes supression of bone marrow and loss of production of WBC and RBC
Why would a patient be given erythromycin instead of penicillin? - Answer patients who are
allergic to penicillin or the organism is resistant to penicillin. Erythromycin has a low toxicity.
And Detailed Answers.
What do we call antibiotics that kill gram negative and gram positive bacteria? - Answer Broad
spectrum drugs (antibiotics) are effective against both gram negative and gram positive
bacteria.
What do we call it when we give the patient 2 or 3 different antibiotics a once? Why would we
do that? - Answer Combination chemotherapy. Pathogens are capable of becoming resistant
to a single agent, but combination chemotherapy (using more than one drug) makes it more
difficult for the pathogen to develop resistance.
What is chemotherapeutic index? - Answer The relationship between toxicity of a compound
for the body and the toxicity for parasites.
If a drug has a low chemotherapeutic index, what does that mean? Is that good or bad? -
Answer Drugs that have a low chemotherapeutic index often inhibit pathways or attack
structures found in the host cells. For example, cancer cells closely resemble normal body cells,
therefore, it is difficult to poison the cancer cells without poisoning the body. A low
chemotherapeutic is bad. The larger the therapeutic index, the better the chemotherapeutic
agent, and the less toxic it is to the host. Drugs often have high therapeutic indexes if the target
of the drug is a structure or pathway not found in the host organism.
A drug has a low selective toxicity. Is that a good or bad thing? - Answer Selective toxicity is
the ability of a chemical or drug to kill a microorganism without harming its host, therefore, a
low selective toxicity is a bad thing.
Name four major methods by which antibiotics work: - Answer 1) inhibit cell wall synthesis
2) inhibit protein synthesis
3) inhibitor of nucleic acid synthesis
4) inhibit folic acid synthesis
Penicillin is made by a ______? - Answer fungus (mold/penicillium)
Who discovered penicillin? - Answer Fleming
,What are three problems with penicillin? - Answer 1) overuse has led to resistance. Many
bacteria have beta-lactamase (penicillinase), an enzyme which inactivates the penicillin.
2) narrow spectrum
3) anaphylactic reaction: many people allergic
What types of microorganisms are affected by pencillin? - Answer primarily for staph and strep
infections- also syphilis
What do we mean by semisynthetic penicillin? Are they only good for gram positive
microorganisms? - Answer Altered natural beta-lactams create semisynthetic derivatives of
penicillin. These are synthetic and more expensive. They have a broader spectrum than
penicillin due to their modified chemical structures.
Why do they add clavulinic acid to penicillin? - Answer The clavulinic acid inactivates the
penicillinase made by bacteria.
What is beta-lactamase? - Answer A bacterial enzyme that catalyzes the hydrolysis of the
lactam ring in some penicillin antibiotics, rendering them ineffective. Beta-lactamase is also
known as penicillinase.
Cephalosporins are described as first generation, second generation, and third generation. What
is the difference? - Answer first generation are generally used for gram positives. They are
narrow spectrum. second generation are more broad. They kill enterics (gram - and some gram
+). Third generation kills pseudomonas and is broad spectrum killing gram - and even more
gram +.
How do these work? - Answer They work like penicillin by inhibiting cell wall synthesis. They
do this by inhibiting the cross linkages between the NAM and NAG layers of the peptidoglycan
cell wall. The cephalosporins are resistant to beta lactamase enzyme.
Why are these drugs better for some people than penicillin? - Answer They are active against
more organisms and do not cause as many allergic reactions as penicillin.
Name four drugs other than penicillin that inhibit the synthesis of the cell wall: - Answer ABI V.
1. Augmentin
2. Bacitracin
, Which of these drugs is for topical application? - Answer bacitracin
Name 2 drugs that inhibit mycolic acid production/cell wall synthesis in Mycobacteria: - Answer
isoniazid and ethambutol
Why can we give drugs that disrupt ribosomes? Wouldn't that also affect human ribosomes? -
Answer The drugs only affect the 30s ribosomes in prokaryotic cells. Human cells are not
affected because they have 40s ribosomes since they are eukaryotic.
Aminoglycosides are effective against gram _____ bacteria - Answer negative
What are some side effects of aminoglycosides? - Answer 1. hearing loss
2. kidney damage
Tetracycline is considered a ______________ _____________ antibiotic. - Answer broad
spectrum
Tetracycline is effective against intracellular bacteria such as: - Answer chlamydia and rickettsia
Tetracycline is effective against bacteria without a cell wall such as: - Answer mycoplasma
What is the problem with tetracycline and children? - Answer discolors teeth and affects bone.
What drug gets through the blood brain barrier and is great for treating meningitis. (also treats
rickettsia and chlamydia)? - Answer chloramphenicol
Problem associated with chloramphenicol - Answer toxicity in children--> aplastic anemia. This
is very serious as it causes supression of bone marrow and loss of production of WBC and RBC
Why would a patient be given erythromycin instead of penicillin? - Answer patients who are
allergic to penicillin or the organism is resistant to penicillin. Erythromycin has a low toxicity.
