Bacterial Structure and Function Flashcards
antony van leeuwenhock
first to visualize microorganisms via microscope
louis pasteur
proved spontaneous generation of bacteria doesn’t occur
robert koch
“single most important contribution to medical science”
importance of washing your hands
joseph lister
invented antiseptic surgery
kochs postulates
1 the specific organism should be shown to be present in all cases of labortory animals suffering from a specific disease but should not be found in healthy animals
2 specific microorganism should be isolated from diseased animal and grown in culture
3 this isolated microorganism should be able to reinfect a healthy animal
4 should be able to re-culture from this newly infected animal
molecular kochs postulates
1 identify gene or gene product
2 show that it is present in illness and not in health
3 show that disrupting gene disrupts virulence
4 show that inducing gene causes virulence
5 immune responds to gene products
6 gene/protein expressed in vivo
classes of microorganisms
algae, fungi, protozoa, bacteria
bacterial characteristics
many pathogens,
many require organic compounds for energy,
some non-pathogens are photosynthetic,
all have a rigid cell wall,
unique characteristics compared to other classes
differences between prokaryotes and eukaryotes
eukaryotes-
chromosomes, nucleus mitosis mitochondria no cell wall
prokaryotes- 1 circular chromosome, no nucleus, no mitosis no mitochondria- use cell wall use flagella for motility cell wall
h-antigen
serotype to a particular flagellum
bacterial cell wall composition
composed of peptidoglycan, containing
N-acetyl muramic acid
N-acetyl glucosamine,
D- amino acids
other AAs not found in eukaryotes
how large are bacteria
1 um
three general morphological types of bacteria
spherical- coccus
rod shaped- bacillus
spiral shape
why is the arrangement of cells important?
can be identifying features of division
ex. streptococci divide along the same axis forming chains, while staphylococci form irregular clusters
nucleoid
DNA inside bacteria, but unbound by membrane
describe the outer bacterial boundaries (wall, membrane etc.)
inner most- cell membrane
middle- cell wall
outer- outer membrane
capsule
periplasmaic space- b/t cell wall and outer membrane
cytoplasm contents in bacteria
ribosomes (different than eukaryotes)
functions of cell membrane
1 contains oxidative enzymes for energy
2 cell wall synthesis
3 transport
4 secreting toxins
5 pump out select antibiotics
describe the structure of the cell wall
cross linked peptidoglycans- NAM residues crosslinked via peptide bridges and NAG residues
what happens when you destroy the cytoplasmic membrane?
destroys the proton gradient
difference between gram positive and negative
positive- cell wall is outer most layer. has teichoic acids
negative- has an outer membrane. has lipoproteins on cell wall, and LPS on the outer membrane
o-antigen
LPS- is an endotoxin bound to outer membrane
composed of polysaccharide
penicillinases
found in periplasmic spaces of gram negative bacteria
capsule
not necessary- but protective (antiphagocytic)
polysaccharide
often target of Abs
flagella
comprised of flagellin polymer
8-12 um long
amount and location of flagella can be identifying
use for motility
pili/fimbrae
small surface appendages
main function is adherence
F-pili is necessary for reproduction
polymer of pilins
biofilms
adhesion via glycocalyx
spores
gram positive rods are only pathogens that form spores
dormant state that bacteria forms in lack of nutrients
very resistant- presence of dipiconlinic acid
killed by very high heat
secreted factors
exotoxins, proteases, lipases
