Lecture 3 - Bacterial Morphology Flashcards
Bacillus shape is _____
rod shaped
coccus is
spherical
Spiral forms? (2)
spirilla & spirochete (spirochete more tightly coiled)
How is structure of bacteria determined?
The osmotic pressure affects the way cell wall is synthesized bc cell wall responsible for prevent lysis (concentrated cytoplasm)
What would allow a bacterial species to not have a peptidoglycan cell wall?
If in an isotonic environment
What is the best way to prev the growth or kill bacteria?
create drugs/toxins that exploit cell wall synthesis
What does the lipopolysaccharide do?
protect against THREATS
- immune system
- antibiotics
- toxins
Common features of eubacterial cells include: (4)
- viscous cytoplasm (concentrated)
- circular chromosome in nucleoid
- Cell wall of peptidoglycan
What makes up most of the bacterial composition during balanced exponential growth?
lots of proteins and lots of RNA (all three types)
What is the difference between the bacterial envelopes of gram neg and gram positive?
gram negative have two membranes and a peptidoglycan cell wall (thin)
gram positive have one membrane and multilayer peptidoglycan
What is the s layer and when is it needed?
It is needed in hostile environments and protects against phagocytosis
What parts of the phosphoglyceride can be changed depending on the environment?
- the attachment of other molecules to phosphoryl head group
- the fatty acid chain eg cold temp may lead to bact with more cis unsaturated bonds to create kinks that increase fluidity.
What things affect cell membrane fluidity ?
- temperature
- cholesterol
- saturation
What can easily passively transport ?
small uncharged hydrophobic molecules or water due to osmosis
What diffuses slowly across membranes?
large charged polar molecules
What can cross membranes when not ionized?
-weak acids and bases
If want passive diffusion of hydrophilic solutes across membrane need?
Desolvation, so using transport can decrease energy needed to cross membrane
Active vs passive transport concentration gradient?
active is against, passive is with
What can bacteria synthesize but humans can not?
vitamins
What is ABC transporter?
An ATP binding cassette transporter - ATP binds onto transporter so solute can go through, not the actual hydrolysis of ATP.
What does the bacterial cell wall consist of? (go beyond peptidoglycan)
Polymer of alternating N-acetylglucosamine & N -acetylmuramic acid sugars
What subunit of peptidoglycan contains 4-6 peptide residues?
N-acetylmuramic acid
What linkage is peptidoglycan?
1,4 Beta linkage
What makes 1,4 Beta linkage good?
protects against hydrolysis
What does cross link between polymer chains help with?
Strength & shape
What do most drugs attack specifically about peptidoglycan?
the cross link between M-M
Why does the cross link of muramic acids have D-aa?
to avoid protease recognition
What helps keep cell wall rigid and withstand turgor pressure?
sacculus
What is the difference between a persistent and resistant bacteria?
A persistent bacteria - does not grow, so unaffected by a drug while a resistant bacteria - is unaffected by a drug
Why bacteria blow up at center?
bc septum is where peptidoglycan break down and new one form for the dividing bacteria
Negative gram bacteria have outer cell walls that are ____ & is another ____ to overcome
toxic and barrier
What is the difference between endotoxin and exotoxin?
Exotoxin is toxin a bacteria can release when its alive and endotoxin is something it releases after it dies eg septic shock from overwhelmed immune sys
What is example of endotoxin?
LPS
What part of the LPS do toll like receptors recognize?
Lipid A
What connects outer to inner?
murein lipoprotein
What is unique about O antigens?
they are highly variable
Why useful O antigen highly variable? What else can they do?
avoid immune detection & protect against detergents
Secondary active transport usually involves what integral protein?
Symporter eg free energy from ion down its concentration gradient
What do detergents do to compromise cell membranes?
dissolve membrane by forming micelle around lipids and integral proteins (hydrophobic parts)
O antigens helps prev dissolve lipid by protect against detergent, so what does Lipid A do?
Lipid A helps protect against hydrophilic
What do you need if you want big, charge things into cell? What does this mean for how organism can be exploited?
transport ; certain threats to the bacteria can recognize the bacteria by the specific receptor they express eg. LamB maltose & viral recognition.
What beta barrel protein helps mediate export of Ab and toxins?
Beta barrel protein TolC
What does the gram positive cell envelope have? What two envelope characteristics do gram - bact also have?
capsule, S-layer, teichoic acids ; capsule & S-layer
What envelope layer has pores, hard to detect even by gene seq, and have several arrangements?
S-layer
What is teichoic acid that bind to peptidoglycan ?
wall teichoics acids.
Teichoic acid attached to lipid membrane?
lipoteichoic acid
What species has a very unique cell envelope?
Mycobacterium Tuberculosis
What are the consequences of large/unique cell env of Mycobacterium Tuberculosis?
- slow growth bc can’t bring all the resources necessary in as quickly
- less permeability to drugs
