Bacterial Structure and Classification Flashcards
What are round bacterium called? Rod shaped?
cocci = round bacilli = rod
What would a chain of round bacterium be called? Sets of two?
streptococci = chain diplococci = doublets
What would a grape-like cluster of cocci be called?
staphylococci
What are comma shaped bacterium called
vibria
What are corkscrew shaped bacterium called?
spirilli and/or spirochetes
Describe the difference between prokaryotic DNA and eukaryotic.
Prokaryotic DNA is usually found in a single, circular chromosome that lacks introns and histones
What are bacterial cell walls composed of? If they are Gram + what is up to 50% of it composed of?
peptidoglycan.
Gram + cell walls contain up to 50% teichoic acid or lipoteichoic acid
Which has a tightly woven, cross-linked cell wall: gram + or -
Gram + is tightly woven and cross linked
Which type of bacterium has two cellular membranes: gram + or -
Gram - bacteria have an inner cell membrane, then the cell wall, then an outer cell membrane
A cellular membrane is found to lack sterols. Is it likely prokaryotic or eukaryotic?
prokaryotic cytoplasmic membranes lack sterols, whereas eukaryotic membranes rely on them.
Which have larger ribosomes: prokaryotes or eukaryotes?
eukaryotes
What purposes do pili serve?
they allow ‘sexual’ transmission of genes between bacteria during conjugation
and
allow bacteria to anchor to hosts
What are capsules composed of?
polysaccharide or polypeptides
What unique ability do some Gram + bacteria have that allows them to survive extremely harsh conditions for expansive lengths of time?
generation of spores: dehydrated, dormant forms that allow potential pathogens to survive for up to centuries in harsh conditions. Ex: anthrax
What is the region between the two membranes of a gram - bacteria called? What lies within this region?
Periplasmic space. The peptidoglycan cell wall layer and a host of degradative enzymes that can potentially destroy antibiotics.
Does the outer membrane of a Gram - bacteria have a charge? If so, what is it and what is its purpose?
Negative charge that helps these bacteria evade phagocytosis, hinder antibiotic uptake, and avoid action of complement.
How to bacteria uptake nutrients through their membranes and cell walls?
proteins called porins
If LPS (lipopolysaccharide) is found in a bacteria what do you know?
That it is Gram -.
What pathologically important things does LPS contain?
Lipid A (aka endotoxin) which illicits cytokine reactions and sepsis and O-antigen which is important for serotyping some species
Describe how a Type II system works in secreting bacterial compounds.
In Type II systems, proteins are secreted from the cytoplasm into the periplasm. Once there, they are secreted across the outer membrane.
Which protein secretion system is found ONLY in pathogenic bacterium? Describe it.
Type III (molecular syringe). Injects proteins from cytoplasm of bacteria, across both membranes and directly into the cytoplasm of the attached host animal cell.
Which protein secretion system is a member of the ABC (ATP binding cassette) and found in all Gram negative bacteria? Describe it.
Type I. proteins are secreted directly into the extracellular environment by the ATP binding cassette transporters
What is peptidoglycan composed of?
repeating disaccharides of NAG and NAM to form long chains called Transglycosylase.
A pentapeptide is attached to each NAM and these pentapeptides cross-link to eachother to form the sugar backbones with the help of transpeptidase and carboxypeptidase enzymes (penicillin binding proteins).
What is the target of penicillin and many antimicrobials in gram + bacteria?
The terminal D-alanine pair in the pentapeptides.
