Bacteriology Overview Flashcards
Four things in common with Prokaryotic and Eukaryotic cells
cell membrane
cytoplasm
DNA
ribosomes (different types)
Prokaryotic cells
no nucleus and no membrane encolosed organelles.
tend to be smaller and more simplistic
Eukaryotic Cells
have a nucleus and membrane enclosed organelles
tend to be larger and more complex
Cytoplasm
jelly like aqueous solution contains three main groups of molecules: macromolecules, small molecules and inorganic ions
facilitate chemical reactions and dissolve soltes
contains nucleoid and ribosomes
macromolecules
proteins (enzymes), nRNA and tRNA
small molecules
energy sources, precursors of macromolecules, metabolites or vitamins
inorganic ions
required for enzymatic activity (co-factors)
Nucleoid
nucleus- like structure contains: DNA, proteins, RNA
Bacterial Chromosomal DNA
large circular macromolecule
loop formation caused by nucleoid- associated protiens (NAPs) bound to DNA
DNA supercoiling is mediated by enzymes: DNA gyrase and topoisomerase I
Protein in nucleoid include:
proteins involved in DNA compaction
Transcription factors that regulate expression of bacterial genome
Messenger RNA
mRNA encodes for proteins
Non coding RNA
ncRNA is involved in DNA organization and expression of bacterial genome
1 base pair
1 bp is one pair of nucleotide bases that connect the complementary strands of DNA
Plasmid
circular molecule of DNA that replicates separately from chromosome- not part of nucleoid
not essential under normal conditions
has a defind copy number
Virulence factors
genes associated with causing disease
resistance genes
survive in presence of antibiotics and other toxic compounds
conjugation
process that transfers plasmids cell to cell
Bacterial Envelope contains
cytoplasmic membrane cell wall (peptidoglycan layer) periplasmic space outer membrane (gram negative bacteria) capsule (some bacteria) envelope associated: pili/fimbriae, flagella, secretion systems
Bacterial Envelope Functions
protects cell from environment or host packages internal components provides structural rigidity produces energy facilitates uptake of nutrients and efflux of toxic substances
Gram Positive
stains purple
cytoplasmic membrane
thick layer of peptidoglycan
teichoic acids attached to peptidoglycan
Gram Negative
stains pink
outer and cytoplasmic membranes
thin layer of peptidoglycan in the periplasmic space
lipopolysaccharides in outer membrane (LPS or endotoxins)
Cytoplasmic membrane
composed of phospholipid bilayer and proteins
innermost membrane next to cytoplasm
Phospholipid bilayer
each phospholid molecule has a head and two heads
head is hydrophilic
tails are hydrophobic
hydrophobic compounds can enter by passive diffusion
transport proteins
enable specific transport of molecules into cell and export molecules out of cytoplasm
energy generation and electron transport chain
components required for the synthesis of adenosine 5-triphosphate (ATP) by ATP synthase protein
Selective permeability barrier
transport proteins mediate passage of hydrophilic substances into and out of cell
Cell wall: peptidoglycan layer
cell wall is a mesh like essential structure
protects cell from osmotic lysis
provides mechanical protection
selective permeability barrier
prevents passive diffusion of hydrophobic or large compounds
Protective Barrier
common to gram negative bacteria
selective permeability barrier
provides resistance to toxic compounds
provides tolerance to detergents and bile salts
Structure of Protective Barrier
asymmetrical lipid bilayer
porin proteins
transporter proteins
Asymmetrical lipid bilayer
outer leaflet mainly composed of lipopolysaccharide
prevents dissusion of hydrophobic compounds
porin proteins
allow small hydrophilic molecules to passively enter cell
transporter proteins
enable specific transport of important, larger nutrients into the cell
Capsule importance
help bacteria envade immune system
aids in attachment to some surfaces
increased tolerance to antimicrobial agents
Capsule Structure and appearance
polysaccharide layer outside of the cell wall (gram positive) or outer membrane (gram negative)
bacterial colonies have mucoid apperance
Surface components importance
mediates contact with the surrounding enviroment
important for attachment to surface, movement and interactions with other bacteria
flagella
important for motility
long filamentous protein structures
pili/fimbriae
adherence to srufaces or bacterial interaction (biofilm)
shorter and more stiff than flagella
sex pilus
involved bacterial conjugation (transfer of plasmids)
secretion systems
release of proteins into environment or host
typically related to virulence or bacterial communication
Endospores
dormant bacteria that can survive adverse conditions for long periods of time
can revert to active state in hose and cause disease by multiplying
gram positive form spores more often
Spore forming bacillus
B. anthracis (anthrax)
P (Bacillus) larvae (american foulbrood)
Spore forming Clostridium
C. perfringens and C. difficile (enterotoxaemia)
C. tentani (tetanus)
C. botulinum (botulism)
obligate aerobes
require oxygen to survive
obligate anaerobes
dont need oxygen to survive
faculatative anaerobes
can grow with or without air
better growth in aerobic conditions
aerotolerant anaerobes
grow equally well with and without oxygen
