antibiotics II

Question 1

what parts of cell do the antibiotics target in bacterial cells

Answer 1

cell wall (peptidoglycan), plasma membrane, ribosomes, DNA synthesis, Metabolic pathways

Question 2

antibiotics target peptidoglycan – glycopeptide

Answer 2

vancomycin is a glycopeptide.
– binds to D-ala-D-ala and prevents the incorporation of the NAM/NAG peptide subunits into the peptidoglycan matrix.

Question 3

vancomycin is a ..

Answer 3

broad spectrum antibiotic

Question 4

what does vancomycin have activity against

Answer 4

methicillin resisitant staphylococcus aureus (MRSA) – generally reserved for serious drug resistant gram positive infections

Question 5

antibiotics target peptidoglycan – B-lactams

Answer 5

penicillin and its derivative, amoxicillin, prevents cell wall biosynthesis by binding to and inhibiting these penicillin binding proteins – inhibiting cross-linking

Question 6

what are B-lactams used for

Answer 6

to treat ear infections

Question 7

antibiotics target peptidoglycan – bacitracin

Answer 7

prevents the transport through the cell membrane of a component of peptidoglycan

Question 8

what is bacitracin an ingredient in

Answer 8

polysporin

Question 9

treatment of glycopeptide, b lactams, or bacitracin have no effect on..

Answer 9

stationary cells since those cells are not synthesizing peptidoglycan, and has little to no affect on gram negative bacteria

Question 10

why do glycopeptide, b lactams, or bacitracin have no effect on gram negative bacteria

Answer 10

because of the outer membrane, which prevent access to the peptidoglyan layer.

Question 11

antibiotics target membranes .. which type of gram bacteria

Answer 11

gram negative – looking at outer membrane which is unique to gram -

Question 12

what happens to the outermembrane when antibiotics target it..

(polymyxin B)

Answer 12

polymyxin B binds to the phospholipids and to lipid A which disrupts the outer membrane of gram negative bacteria.

– the affected membrane develops temporary cracks, which permit passage of various molecules, allowing polymyxin B to enter and kill cell

Question 13

polymyxin B is used to treat..

Answer 13

infections in eye, and infections in bloodstream and lungs

Question 14

bacterial cell membranes can also be breached by..

Answer 14

colicins

Question 15

colicins do what
and what kind of spectrum are they

Answer 15

inhibit cell wall synthesis and therefore have negative effects on the peptidoglycan layer.
– narrow spectrum because of specxific receptors they bind to

Question 16

process of how colicins work

Answer 16

the colicin will bind to the bacterial membrane proteins and the gets internalized through a channel like TolC.
– once inside, the colicin will have some effect to kill the bacteria.

Question 17

antibiotis target ribosomes – what are the three examples of antibiotics we talked about

Answer 17

macrolides, aminoglycosides, and tetracyclines

Question 18

macrolides

Answer 18

prevent peptide bond formation, thus stopping protein synthesis resulting in bacterial cell death

Question 19

what type of macrolides is used and to treat what

Answer 19

erythromycin – whooping cough and syphilis

Question 20

aminoglycosides

Answer 20

mechanism of action is through binding to the bacterial 30S ribosomal subunit, causing the misreading of tRNA, thus causing the bacterium to synthesize faulty proteins. – leads to cell death

Question 21

what type of aminoglycosides are used and to treat what

Answer 21

streptomycin – mycobacterium tuberculosis

Question 22

tetracyclines

Answer 22

bind to the bacterial 30S subunit, blocks binding of tRNAs therefore prevents protein synthesis

Question 23

what type of tetracyclines is used to treat what

Answer 23

doxycycline – chlamydia

Question 24

what is an important metabolic pathway in bacteria

Answer 24

folic acid biosynthesis

Question 25

what are folic acids

Answer 25

precursor for RNA and DNA

Question 26

what are used together to block folic acid synthesis

Answer 26

sulfonamides and trimethoprim

Question 27

when sulfonamides and trimethoprim are perscribed together what does it treat

Answer 27

eye, skin and vaginal infections

Question 28

what blocks mycolic acid synthesis

Answer 28

izoniazid

Question 29

izoniazid process of blocking mycolic acid synthesis

Answer 29

in mycobacterium tuberculosis. -- izoniazid is taken up by the bacteriym, and then activated by an enzyme produced by the bacterium with the result that mycolic acid synthesis is prevented

Question 30

what happens when mycolic acid synthesis is prevented

Answer 30

the cell wall will be weakened and are more prone to being killed by immune system. --

Question 31

why are the cell walls weakened when mycolic acid synthesis is prevented

Answer 31

because mycolic acid is part of the mycobacterium's cell wall

Question 32

antibiotics that target nucleic acid biosynthesis -- example of enzyme

Answer 32

fluoroquinolones

Question 33

what are fluoroquinolones in terms of the spectrum of antibiotics

Answer 33

broad

Question 34

type of fluoroquinolones

Answer 34

ciprofloxacin

Question 35

ciprofloxacin

Answer 35

last line of defense against antibiotic resistant organisms -- most valued at the moment -- also known as the gyrase inhibitor

Question 36

breakdown of process that happens when ciprofloxacin is introduced to system

Answer 36

DNA is found in the nucleoid - to be replicated, has to be unwound by the enzyme called gyrase (helicase unzips the DNA and gyrase keeps DNA from tangling) - the antibiotic ciprofloxacin binds to the DNA gyrase, and prevents the unwinding/uncoiling of DNA -- this inhibits replication of DNA allowing the cell to be targeted by immune system.

Question 37

targeting fungi is a problem.. why?

Answer 37

it is because fungi are eukaryotic, therefore compounds that inhibit their grrowth or kill them, will also harm human host cells.

Question 38

what is unique to the cell wall of fungi that antibiotics can target without hurting host cell

Answer 38

sterols in the fungi

Question 39

difference between sterols in humans and fungi

Answer 39

humans -- cholesterol fungi -- ergosterol

Question 40

Candida infections of mouth, throat, and bloodstream (skin, vagina) can be treated with

Answer 40

azoles and mycostatins

Question 41

azoles

Answer 41

imidazole interfere with the synthesis of ergosterol in fungal cell membrane

Question 42

mycostatins

Answer 42

nystatin - changes permeability of fungal cell membrane by combining with ergosterol