1: Bacterial Structure & Function

what molecule can be found in the cell wall of both gram-positive and gram-negative bacteria?

peptidoglycan

what molecule is found in only gram-positive bacteria?

lipoteichoic acid

the outer membrane can only be found in which type of bacteria?

gram-negative

what is exclusive to gram-negative bacteria?

lipopolysaccharide (LPS) and lipooligosaccharide (LOS)

what molecule in LPS is recognized by host antibodies in gram-negative bacteria?

o-antigen

which component of LPS is most likely to lead to host toxicity and septic shock?

lipid A

which component of gram-positive bacteria is most likely to lead to host toxicity and septic shock (less common)?

teichoic acid

what is the molecular difference between LOS and LPS?

no o-antigen on LOS

beta-lactamase is typically found in which layer of gram-negative bacteria?

periplasm

beta-lactamase confers bacterial resistance against which antibiotic?

penicillin

which host defensive mechanism is the bacterial capsule most important in protecting against?

phagocytosis

which bacterial organelle facilitates motility?

flagellum

what bacterial structures will mediate the adhesion to host cells?

pilus and glycocalyx

which type of bacteria has the potential to form endospores?

gram-positive

what does an endospore protect the bacterial genome from?

desiccation, radiation, temperature, chemical damage

what stabilizes the genetic material of an endospore?

dipicolinic acid

which bacterial component allows microbes to attach to foreign surfaces?

glycocalyx

what is an aggregation of bacteria referred to as?

biofilm

what is the function of a bacterial biofilm?

allows for grouped protection and evasion from host defenses and antibiotics

what is the shape of cocci bacteria?

sphere

what is the shape of coccobacilli bacteria?

rod-sphere

what is the shape of bacilli bacteria?

rod

what is the shape of spirochete bacteria?

spiral

where does crystal violet dye stain within bacteria?

peptidoglycan

what is the purpose of rinsing a gram stain with iodine?

fixes the dye

what is the role of acetone or ethanol during the gram stain procedure?

decolorizer

what agent dyes gram-negative bacteria red?

safranin

why do gram-positive bacteria retain crystal violet dye more efficiently than gram-negative bacteria?

gram-positive bacteria have thicker cell walls than gram-negative bacteria

why do acid-fast bacteria resist the Gram stain?

they have a mycolic acid layer

what is the function of a glycocalyx capsule?

immune evasion, attachment, and for use in tests/vaccines

what type of Gram-negative pili is used for secretion?

T3SS

what type of Gram-negative pili is used for conjugation?

T4SS