Introduction to Bacteria and Bacterial Diseases Flashcards
what are the three bacterial shapes?
spheres/cocci
rods/bacilli
spirals
what is a diplococci?
Streptococcus pneumoniae
what does the bacterial capsule do?
protects from desiccation and immune response
what makes up the bacterial capsule?
polysaccharides
is the bacterial capsule intra- or extracellular?
extracellular
what does the cell wall contain?
peptidoglycan
what does the cell wall protect from?
mechanical damage
osmotic lysis
what makes something gram positive?
thick peptidoglycan layer
what makes something gram negative?
thin peptidoglycan layer covered by lipopolysaccharide
true/false: there are bacteria that show variable gram staining
true
Mycobacteria
what makes up the plasma membrane?
phospholipids and proteins
what is the function of the plasma membrane?
flexible barrier
transport
what are plasmids?
small, circular DNA
replicate autonomously
physically distinct from chromosome
why do we care about plasmids?
encode virulence factors and resistance genes
transmissible
pili are for _____________. also known as ______________
adhesion
fimbriae
flagella are for ___________
motility
in what are flagella more common?
gram negative
what is the important protein in flagella?
flagellin
what is genetic variation in bacteria induced by?
mutation: spontaneous or induced
where do spores divide?
within cell walls
what is conjugation via F-pilus?
F-pilus transfers DNA from donor to recipient
what is transduction?
DNA transfer by (bacterio)phages
in conjugation via F-pilus, proteins involved are encoded on a __________
plasmid
where is transformation (uptake DNA directly) usually seen?
laboratory experiment
has been documented in natural
what are bacterial virulence factors?
bacteria-associated molecules that are required for a bacterium to cause disease while infecting eukaryotic hosts
what are the classes of virulence factors in bacteria?
adhesins
toxins and enzymes
capsule
secretion systems
super-antigens
how do adhesins binding to host cell receptors alter the host cell?
trigger intracellular signaling
induce endo- or phagocytosis
promote transport
change gene expression
what is an E. coli adhesin?
FimH
define endotoxins
components of bacterial cell wall released when bacteria are lysed
define exotoxins
produced and secreted by live bacteria
many types
what are some properties of endotoxin (LPS)?
heat stable
antigenic
activates host cells
what do high levels of endotoxins lead to?
endotoxemia: fever, shock, disseminated intravascular coagulation
what is activation by endotoxin?
ligand-receptor interactions that cause intracellular signaling then release of pre-formed products, gene transcription and/or synthesis/release of new products
what are some exotoxins that cause disease?
botulinum toxin
tetanus toxin
Clostridium perfringens toxins
shiga toxin
in which bacteria are secretion systems best known?
gram negatives
what is a streptococci?
Streptococcus pyogenes
what is a species that presents as chains of rods?
Bacillus anthracis
what is a species that presents as flagellate rods?
Salmonella typhi
what is a species that is a spiral/vibrios?
Vibrio cholerae
what is a species that is a spirilla?
Helicobacter pylori
what is a species that is spirochaetes?
Treponema pallidum
what is a bacteria with a capsule?
Bacillus anthracis
what are some important features of spores?
dormant
highly resistant
dehydrated
divides within cell walls
what are two species that are spore-forming?
Bacillus spp
Clostridium spp
what is the structure of LPS?
O-antigen
core
lipid A: most toxic
what do superantigens do?
cross-link the T cell receptors to major histocompatibility molecules: non-specific activation of immune system, massive proinflammatory cytokine release
are endotoxins or exotoxins heat stable?
endotoxins (released from cell wall when lysed)
what is an example of an endotoxin?
lipopolysaccharide from gram positive bacteria
what are some bacteria that have superantigens?
Staphylococcus aureus
Staphylococcus pyogenes
Histophilus spp
