Prokaryotic Microbes Flashcards
(15 cards)
Describe nucleoid of a bacteria
Usually not membrane bound
1 closed circular double stranded DNA molecule
Supercoiling and nucleoid proteins ( different from his tone proteins that aid in folding )
What are episomes
Plans,ids that may integrate into chromosomes in the bacteria cell
Describe the structure of peptidoglycan
Mesh like polymer of two identical sugars (NAG & NAM) and pentapeptide ( made of L and D amino acids )
What shape do peptidoglycan strands have
Helical
In what strand of bacteria do peptidoglycan chains cross linked directly
E coli
In what strain of bacteria are peptidoglycan chains linked with peptides for strength
S aureus
What is importance of peptide cross links
Helps prevent cell from bursting under osmotic pressure
In some gram positive cell walls, teichoic acids can be found. What do they do
Anchor cell wall to plasma membrane
Protect from environmental substances
May bind to host cells
Describe structure of gram negative cell wall
Thin layer of peptidoglycan and then additional layer of cell membrane on top thag acts as a selective permeable membrane, allowing diffusion of low molecular weight solutes by porins
Lipopolysaccharide
Consists of; lipid A, core polysaccharide, O side chain( O antigen)
Lipid A embedded in outer membrane- LPS unique to bacterial OM( Gram -ve)
Contributes to -ve charge on cell surface
LPS cam act as endotoxin amd can stimulate strong immune response leads to septic shock
Patterns of flagellelation
Monotrichous- one flagellum
Polar flagellum- flagellum end of cell
Amphitrichpus- one flagellum at end of each cell
Lophotrichous- cluster of flagella at one or both ends
Petritrichpus - spread over entire cell
Role of endospores
Mom growing structures that contain a copy of the genome
What are archael membranes composed of
Hydrocarbons derived from isoprene units attached to glycerol by ether linkages
How do prokaryotes replicate
Asexual reproduction usually binary fission
What’s a method to measure cell mass of replicating prokaryotes
Measure optical density of bacterial culture
Spectrophotometer passed light of specific wavelength through microbial suspension
Higher cell density - more light scattered , less light transmitted into detector
