Cell wall stuff Flashcards
What is cell wall responsible for?
Shape of cell
What are the major functions of the cell wall?
Prevents bacterial cells from rupturing when pressure of water inside the cell is greater than the outside
Maintains shape and is anchor point for flagella
Contributes to the ability of some species to cause disease
Site of action for some antibiotics
What is cell wall composed of?
Macromolecular network called peptidoglycan
What does peptidoglycan consist of?
A repeating disaccharide connected by polypeptides which forms a lattice that surrounds and protects the cell
What is the disaccharide portion of peptidoglycan made of?
Monosaccharides NAG and NAM
These are related to glucose
Gram Positive bacteria
Have many layers of peptidoglycan
Thick rigid structure
Contain techoic acids
Polyssacharides and techoic acids provide antigenic specificity
Techoic acids info
Lipotechoic acids links cell wall to plasma membrane
Wall techoic acid links the peptidoglycan
Carries negative charge because of phosphate
Regulates movement of cations
Gram Negative bacteria have how many layers of peptidoglycan?
One or very few
Contains an outer membrane as well
Gram negative cell walls do not contain teichoic acids because they’re more susceptible to mechanical breakage. True or false?
True
What is periplasm? (Gram Negative)
Gel- like fluid in periplasmic space
What do gram negative bacteria protect against?
Phagocytes
Complement
Antibiotics
What are gram negative bacteria made out of?
Lipopolysaccharide (LPS)
What does Lipopolysaccharide conain?
O polysaccharide : functions as antigen
Core polysaccharide: Unusual sugars
Lipid A :Endotoxin embedded in top layer
Gram positive gram stains
Alcohol dehydrates peptidoglycan
CV1 crystals do not leave
Gram negative gram stains
Alcohol dissolves outer membrane and leaves holes in peptidoglycan
CV1 washes out; cells are colorless
Safranin added to stain cells
Atypical cell wall examples
Archaea
Mycoplasma
Mycoplasma
Smallest known bacteria that can grow and reproduce outside living host cells
Plasma membranes contain lipids called sterols which protects them from lysis
Archaea
Lack cell walls or have unusual walls made of polysaccharides and proteins but has peptidoglycan
Contain pseudomurein
Pseudomurein (archaea)
Contain N-acetyltalosaminuronic instead of NAM
Lacks d amino acid
Cannot be gram stained but appear gram negative
What is the acid fast stain used to identify?
Bacteria of genus Mycobaterium
Pathogenic species of Nocardia
These bacteria contain high concentrations of hydrophobic waxy lipid which prevents uptake of dyes
Acid fast bacteria can be stained with?
Carbolfuchsin
What does the carbofuchsin do?
Penetrates cell wall and binds to cytoplasm
