LEC 1

Question 1

Which bacteria type has a thicker PG layer, Gram + or - ?

Answer 1

+

Question 2

Gram + bacteria have _ membrane(s); gram - have _ membrane(s)

Answer 2

1, 2

Question 3

Gram + peptidoglycans contain an ______ residue

Answer 3

L-lysine

Question 4

Gram - peptidoglycans contain ______

Answer 4

mesodiaminopimelic acid (DAP)

Question 5

In gram _ bacteria, beta lactamases are confined to the periplasmic space

Answer 5

-

Question 6

In gram _ bacteria, beta lactamases are excreted through the cell wall to the external enviornment

Answer 6

+

Question 7

Transpeptidase catalyzes bond formation between 2 ___ residues and one ____

Answer 7

glycine; d-ala

Question 8

Result of Peptidoglycan cross linking:

peptide-____-_____-_____-peptide

Answer 8

D-ala-glycine-glycine

Question 9

BL Mechanism: Beta lactams _____ the transpeptidase ___ residue in the enzyme active site

Answer 9

acetylate; serine

Question 10

BL Mech: acetylation of the serine residue ____ transpeptidase, leading to a defective cell wall, ____ stress, cell lysis and death

Answer 10

inactivates

osmotic

Question 11

Beta lactams are bacterio____

Answer 11

cidal

Question 12

Beta lactams are highly reactive due to a highly strained _______

Answer 12

4 membered ring

Question 13

Mechanisms of resistance to beta-lactams:
____ cellular uptake
mutation of _____ changing the affinity

Answer 13

decreased

PBPs

Question 14

Mechanisms of resistance to beta lactams:
presence of _____ ____ that pumps AB out
Induction of bacterial ________, catalyzing hydrolysis

Answer 14

efflux pump

beta-lactamases

Question 15

Penicillin allergy results from the drug acting as a ____ and _____ host protein

Answer 15

hapten;

acylating

Question 16

Products of penicilling degradation under acidic conditions (ie stomach):

Answer 16

benzylpenicillenic acid; benzylpenillic acid; benzylpenicilloic acid

Question 17

Electronegative side chains reduce ____, stabilizing penicillin against hydrolysis under _____ conditions, and increasing ____ viability

Answer 17

nucelophillicity; acidic; oral

Question 18

Penicillin __ is typically administered IV; and penicillin _ is typically oral

Answer 18

G; V

Question 19

Water soluble penicillins are typically ____ protein bound, while lipophillic penicillins are usually ____ protein bound

Answer 19

less

more

Question 20

Ampicillin is the ____ protein bound and most water soluble; _____ is the most protein bound and most _____

Answer 20

least;

cloxacillin, lipophillic

Question 21

More lipophillic side chains = _____ bioavailability and _____ degradation

Answer 21

less; less

Question 22

Beta lactams are excreted via ____ or ____ routes

Answer 22

renal, biliary

Question 23

90% of renal excretion is due to tubular _____

Answer 23

secretion

Question 24

Penicillin are (Cationic or anionic); thus, we use ____ to increase penicillin’s its half-life

Answer 24

anionic;

probenecid

Question 25

Methicillins (are/are not) sensitive to beta-lactamases. This is due to _____ ____ of the nucelophillic attack on the carbonyl group

Answer 25

are not;

steric hindrance

Question 26

Methicillins are acid stable or acid labile?

Answer 26

LABILE–>use injection

Question 27

MRSA is due to a mutation on the ____, causing low affinity for binding of beta lactams. The gene involved is ___, and the protein is ____

Answer 27

PBPs; mecA; PBP2A

Question 28

Cephalosporins are ___-member rings

Answer 28

6

Question 29

Cephalexin is _____ active. The _____ group is protonated at physicological pH, making the side chain ____ attracting and decreasing hydrolysis under ____ conditions

Answer 29

orally;
amino;
electron;
acidic

Question 30

Carbapenems have a ____ group that replaces the _____ ring seen in penicillin, increasing reactivity

Answer 30

methylene; thiazolidine

Question 31

Imipenem ____ beta-lactamases

Answer 31

inhibits

Question 32

Imipenem is hydrolyzed by renal _______, so administer it along with _____

Answer 32

dehydropeptidase 1, cilastin

Question 33

Example of a monobactam:

Answer 33

aztreonam

Question 34

Aztreonam’s contain a _____ acid group at the ____ position, taking the place of a carboxyl group seen in penicillin

Answer 34

sulfamic; C2