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MCB 5252 Exam 4, MCB 5252 Exam FOUR
Study Guide.
Define chemotherapeutics - Answers✔therapeutic chemicals that treat diseases including
infectious diseases
Define antibiotics - Answers✔example of chemotherapeutic which are antibacterial agents
Define antimicrobial agents - Answers✔chemicals that kill infectious agents
cidal agent - Answers✔kills microbes
toxic dose - Answers✔drug level at which drug becomes too toxic for the patient
side effects - Answers✔undesirable effects of drugs on host cells
static agent - Answers✔inhibits growth of microbes
broad spectrum drugs - Answers✔attack many different pathogens
narrow spectrum drugs - Answers✔attack only a few different pathogens
which organisms make antibiotics and why - Answers✔Fungi-Penicillium
Bacteria
Bacillus, Actinomyces
Produced for antagonistic effect (killing competition for space and nutrients)
Not necessary for life, just for competition as it takes energy to make these antibiotics
Name the typical targets of antibiotics - Answers✔Cell wall
Protein synthesis
Metabolic antagonists
Nucleic acid synthesis inhibition
Cell membrane
1
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what is meant by selective toxicity - Answers✔ability of drug to kill or inhibit pathogen while
damaging host as little as possible
Therapeutic dose vs Therapeutic index - Answers✔Therapeutic dose: drug level required for
clinical treatment
Therapeutic index: ratio of toxic dose to therapeutic dose
Toxic dose / therapeutic dose = therapeutic index
The higher the index the safer the drug
Define Therapeutic dose - Answers✔drug level required for clinical treatment
Define Therapeutic index - Answers✔ratio of toxic dose to therapeutic dose
List antibiotics that target cell wall synthesis - Answers✔cycloserine
glycopeptides (vancomycin)
Beta lactam (penicillins, cephalosporins)
bacitracin
cycloserine - Answers✔Affects synthesis of building blocks (NAM, NAG)
glycopeptides (vancomycin) - Answers✔Block transpeptidation
Treat antibiotic resistant staph (MRSA) and enterococcal infections
Considered "drug of last resort" b/c rise in resistance to vancomycin is of great concern
bacitracin - Answers✔Prevents transport across cell membrane
Beta lactam - Answers✔penicillins, cephalosporins
Penicillin:
Inhibit peptidoglycan synthesis
Inhibit last step in bacterial cell wall synthesis (leads to lysis of cell)
Acts only on growing bacteria that are synthesizing new peptidoglycan
Resistance to penicillin is growing
Beta-lactamase (penicillinase) is made by resistant organisms and hydrolyzes the bond of the
penicillin ring structure
1-5% of adults are allergic
2
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Name steps in bacterial cell wall synthesis that could be target of antibiotics -
Answers✔Synthesis of building blocks
Transpeptidation
Peptidoglycan synthesis
What are the important features of vancomycin? - Answers✔Block transpeptidation
Treat antibiotic resistant staph (MRSA) and enterococcal infections
Considered "drug of last resort" b/c rise in resistance to vancomycin is of great concern
it is a glycopeptide that inhibits cell wall synthesis by blocking transpeptidation
List the classes of antibiotics that target protein synthesis mechanism, -
Answers✔aminoglycoside
tetracycline
macrolide (erythromycin, cholarmphenicol)
Mech of action for Aminoglycoside antibiotics - Answers✔(streptomycin, gentamicin)
Bind to 30S ribosomal subunit and cause misreading of mRNA and premature release of
polypeptide
Mechanism of action for Tetracycline - Answers✔Broad spectrum, static
Combine with 30S ribosomal subunit and inhibit binding of aminoacyl-tRNA molecules to A-
site of the ribosome
Sometimes used to treat acne
Mechanism of action for Macrolide antibiotics (erythromycin, chloramphenicol) -
Answers✔Erythromycin
Broad spectrum - static
Binds to 23S rRNA of 50S ribosomal subunit and inhibits peptide chain elongation
Used for patients allergic to penicillin
Chloramphenicol
Binds to 23S rRNA on 50S ribosomal subunit and inhibits peptidyl transferase reaction
Toxic with numerous side effects; only used in life-threatening situations
General mechanisms of action for antibiotics that target protein synthesis - Answers✔Antibiotics
bind specifically to prokaryotic ribosome
3
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30S (small) or 50S (large) ribosomal subunit
aminoacyl-tRNA binding
Peptide bond formation
mRNA reading
translocation
Name drugs targeting: cell membrane - Answers✔cell membrane (ergosterol) inhibition "anti-
fungal"
- Polyenes- inhibit function of ergosterol, Amphotericin B (common for systemic infection) and
nysatin
-Azoles- inhibit synthesis of ergosterol: Fluconazole
Name drugs targeting DNA and/or RNA - Answers✔Nucleic Acid synthesis (Quinolones)
Block DNA replication: inhibit DNA polymerase/helicase
Block transcription: inhibit RNA polymerase
Drugs are not as selectively toxic as other antibiotics
Quinolones: inhibit DNA replication
Broad spectrum
Inhibit bacterial DNA gyrase and topoisomerase
Eg. Ciprofloxacin, Naladixic acid
Cipro used to treat anthrax
Rifampin: inhibit RNA/transcription
RNA polymerase inhibitor
metronidazol - Answers✔Treats anaerobic infections (bacteria, fungal or protozoan/parasite
infection)
Name drugs targeting metabolic activities - Answers✔Antimetabolites (Trimethoprim)
Molecules that are structurally similar to, and compete with, naturally occurring metabolic
intermediates
Block functioning of metabolic pathways by competitively inhibiting the use of metabolites by
key enzymes
Trimethoprim: interferes with folic acid production (blocks two steps in folic acid synthesis)
4
MCB 5252 Exam 4, MCB 5252 Exam FOUR
Study Guide.
Define chemotherapeutics - Answers✔therapeutic chemicals that treat diseases including
infectious diseases
Define antibiotics - Answers✔example of chemotherapeutic which are antibacterial agents
Define antimicrobial agents - Answers✔chemicals that kill infectious agents
cidal agent - Answers✔kills microbes
toxic dose - Answers✔drug level at which drug becomes too toxic for the patient
side effects - Answers✔undesirable effects of drugs on host cells
static agent - Answers✔inhibits growth of microbes
broad spectrum drugs - Answers✔attack many different pathogens
narrow spectrum drugs - Answers✔attack only a few different pathogens
which organisms make antibiotics and why - Answers✔Fungi-Penicillium
Bacteria
Bacillus, Actinomyces
Produced for antagonistic effect (killing competition for space and nutrients)
Not necessary for life, just for competition as it takes energy to make these antibiotics
Name the typical targets of antibiotics - Answers✔Cell wall
Protein synthesis
Metabolic antagonists
Nucleic acid synthesis inhibition
Cell membrane
1
, ©FYNDLAY
what is meant by selective toxicity - Answers✔ability of drug to kill or inhibit pathogen while
damaging host as little as possible
Therapeutic dose vs Therapeutic index - Answers✔Therapeutic dose: drug level required for
clinical treatment
Therapeutic index: ratio of toxic dose to therapeutic dose
Toxic dose / therapeutic dose = therapeutic index
The higher the index the safer the drug
Define Therapeutic dose - Answers✔drug level required for clinical treatment
Define Therapeutic index - Answers✔ratio of toxic dose to therapeutic dose
List antibiotics that target cell wall synthesis - Answers✔cycloserine
glycopeptides (vancomycin)
Beta lactam (penicillins, cephalosporins)
bacitracin
cycloserine - Answers✔Affects synthesis of building blocks (NAM, NAG)
glycopeptides (vancomycin) - Answers✔Block transpeptidation
Treat antibiotic resistant staph (MRSA) and enterococcal infections
Considered "drug of last resort" b/c rise in resistance to vancomycin is of great concern
bacitracin - Answers✔Prevents transport across cell membrane
Beta lactam - Answers✔penicillins, cephalosporins
Penicillin:
Inhibit peptidoglycan synthesis
Inhibit last step in bacterial cell wall synthesis (leads to lysis of cell)
Acts only on growing bacteria that are synthesizing new peptidoglycan
Resistance to penicillin is growing
Beta-lactamase (penicillinase) is made by resistant organisms and hydrolyzes the bond of the
penicillin ring structure
1-5% of adults are allergic
2
, ©FYNDLAY
Name steps in bacterial cell wall synthesis that could be target of antibiotics -
Answers✔Synthesis of building blocks
Transpeptidation
Peptidoglycan synthesis
What are the important features of vancomycin? - Answers✔Block transpeptidation
Treat antibiotic resistant staph (MRSA) and enterococcal infections
Considered "drug of last resort" b/c rise in resistance to vancomycin is of great concern
it is a glycopeptide that inhibits cell wall synthesis by blocking transpeptidation
List the classes of antibiotics that target protein synthesis mechanism, -
Answers✔aminoglycoside
tetracycline
macrolide (erythromycin, cholarmphenicol)
Mech of action for Aminoglycoside antibiotics - Answers✔(streptomycin, gentamicin)
Bind to 30S ribosomal subunit and cause misreading of mRNA and premature release of
polypeptide
Mechanism of action for Tetracycline - Answers✔Broad spectrum, static
Combine with 30S ribosomal subunit and inhibit binding of aminoacyl-tRNA molecules to A-
site of the ribosome
Sometimes used to treat acne
Mechanism of action for Macrolide antibiotics (erythromycin, chloramphenicol) -
Answers✔Erythromycin
Broad spectrum - static
Binds to 23S rRNA of 50S ribosomal subunit and inhibits peptide chain elongation
Used for patients allergic to penicillin
Chloramphenicol
Binds to 23S rRNA on 50S ribosomal subunit and inhibits peptidyl transferase reaction
Toxic with numerous side effects; only used in life-threatening situations
General mechanisms of action for antibiotics that target protein synthesis - Answers✔Antibiotics
bind specifically to prokaryotic ribosome
3
, ©FYNDLAY
30S (small) or 50S (large) ribosomal subunit
aminoacyl-tRNA binding
Peptide bond formation
mRNA reading
translocation
Name drugs targeting: cell membrane - Answers✔cell membrane (ergosterol) inhibition "anti-
fungal"
- Polyenes- inhibit function of ergosterol, Amphotericin B (common for systemic infection) and
nysatin
-Azoles- inhibit synthesis of ergosterol: Fluconazole
Name drugs targeting DNA and/or RNA - Answers✔Nucleic Acid synthesis (Quinolones)
Block DNA replication: inhibit DNA polymerase/helicase
Block transcription: inhibit RNA polymerase
Drugs are not as selectively toxic as other antibiotics
Quinolones: inhibit DNA replication
Broad spectrum
Inhibit bacterial DNA gyrase and topoisomerase
Eg. Ciprofloxacin, Naladixic acid
Cipro used to treat anthrax
Rifampin: inhibit RNA/transcription
RNA polymerase inhibitor
metronidazol - Answers✔Treats anaerobic infections (bacteria, fungal or protozoan/parasite
infection)
Name drugs targeting metabolic activities - Answers✔Antimetabolites (Trimethoprim)
Molecules that are structurally similar to, and compete with, naturally occurring metabolic
intermediates
Block functioning of metabolic pathways by competitively inhibiting the use of metabolites by
key enzymes
Trimethoprim: interferes with folic acid production (blocks two steps in folic acid synthesis)
4
