MicroBio Quiz 3 CH.18

pathogenicity island

a genomic island that contains virulence factors

genomic island

chunk of DNA in a microbe’s genome that comes from another organism through horizontal gene transfer

how to spot a pathogenicity island

if the transferred island increases the “fitness” of a microorganism during interaction with a host

adhesin

any microbial factor that promotes attachment

types of adesins

pili, nonpilus adhesins

type I pili

static, hair-like appendages used only for attatchment

how do pathogens evolve

from non pathogens via horizontal gene transfers

virulence genes

encode proteins that enhance the organism’s disease-causing ability

type IV pili

dynamic, thin, and flexible, for twitching mobility

biofilms

allow microorganisms to adhere to any surface and help the bacteria survive in hostile environments

capsules

coat bacterial cell walls and can prevent phagocytes from binding

phagocytes

cells that protect the body by ingesting harmful foreign particles, bacteria, and dead or dying cells

protein A

can sequester antibodies

cytokines

small proteins secreted by cells of the immune system and other cell types

intracellular pathogens

avoid innate and humoral immune mechanisms by living inside host cells

facultative intracellular pathogens

invade host cells but can also survive outside the host cell

obligate intracellular pathogens

invade and reproduce inside a host cell only

A subunit

toxic (active)

B subunit

binds host cell receptors (binding, delivery)

alpha toxin

forms a seven membered transmembrane pore in target cell membranes

alpha toxin causes

cell contents to leak, cell lysis

anthrax toxin

2 A subunits called edema factor and lethal factor and B subunit called protective antigen

edema factor

causes fluid loss to extracellular species

lethal factor

destroys regulatory cascades and cripples the immune response

endotoxin

part of the outer membrane of the gram negative cell wall that include lipopolysaccharide

type II secretion system

systems use a pilus-like extension to push proteins from the periplasm out of the cell

type III secretion system

uses a molecular syringe to inject proteins from the bacterial cytoplasm into the host cytoplasm

type IV secretion system

systems use conjugation-like machinery to export proteins from the cytoplasm

rhinovirus

nonenveloped, single-stranded, positive-sense RNA virus

infleunza

single-stranded, negative sense, segmented RNA genome

Antigenic variation

100 known serotypes of rhinovirus

antigenic shift

two strains of influenza virus infect the same cell and the genomes get mixed, makes a dramatically different virus

antigenic drift

random mutations can occur within the cell that a virus infects, creating small changes in virus proteins