Bacteria Cell Structure- Test 1 Flashcards
What is the average size of bacteria?
0.2-2.0um diameter x 2 to 8um length
There is great variety in bacteria but typically described by one of three basic shapes. What are those shapes?
-coccus- spherical
-bacillus- rod
-coccobacillus- short, plump
-vibrio- gently curved
-spirillum- helical, twisted rod
-spirochete- spring-like
What does the arrangement of cells depend on?
the pattern of division and if/how cells remain attached after division
rigid polysaccharide layer that provides strength
peptidoglycan
Do gram-positives and gram-negative cells have different cell wall structures?
yes
A gram-stain reaction determined by the cell wall thickness does not always what?
correlate with envelope structures
Does a gram-positive or -negative cell have a inner and outer membrane?
negative
How does Archaeal cell walls differ from bacterial?
-they lack peptidoglycan
-typically lack an outer membrane
-most lack polysaccharide wall and instead have s-layer (protein shell)
What is the structure of bacterial lipopolysaccharide?
-they have ionic bonds to divalent cations and add strength
-the LPS replaces most of phospholipids in outer half of outer membrane
-Braun lipoprotein anchors outer membrane to peptidoglycan
-has a toxic component called endotoxin
What are the major events in endospore formation?
starts at the vegetative cell cycle then goes through asymmetric cell division where you have the forespore and the mother cell then you go through engulfment where the mother cell engulfs the forespore and the outer spore membrane is formed then the late sporulation them maturation then the mother cell disappears and there is a free endospore and goes through germination and back into the vegetative cycle
What are the different types of bacterial endospores?
terminal, subterminal, and central endospores
coating of molecules external to the cell wall, made of sugars and/or proteins and have two types, slime layer and capsule
Glycocalyx
What are the functions of glycocalyx?
-protect cells from dehydration and nutrient loss
-inhibit killing by white blood cells by phagocytosis contributing to pathogenicity
-attachment- formation of biofilms
observed in many photosynthetic bacteria, observed in many bacteria with high respiratory activity
plasma membrane infoldings
membrane bound organelle- site of anaerobic ammonia oxidation
anammoxosome in plantomycetes
-functions as energy reserves, carbon or phosphorus reservoirs and/or have special functions
-enclosed by thin protein membrane
-reduces osmotic stress
storage inclusions
smaller than eukaryotic ribosomes (prokaryotic 70s, eukaryotic 80s)
bacteria ribosomes
transfer DNA from one cell to another
conjugative plasmids
carry antibiotic resistance genes
R plasmids
produce bacteriocins substances that destroy closely related species
col plasmids
carry virulence genes
virulence plasmids
carry genes for enzymes
metabolic plasmids
-extrachromosomal DNA found in bacteria, archaea, some fungi; usually small, closed circular DNA molecules
-exist and replicate independently of chromosome; inherited during cell division
-classification via mode of existence, spread, and function
plasmids
-hair-like appendages that allow for attachment
fimbriae
-involved in motility
-conjugation pili involved in DNA transfer from one cell to another
pili
Archaea has what instead of pili?
Hami, also used for attachment, have hooks to help attachment
-long thin appendages anchored in cell at one end
-different arrangements
-increase or decrease rotational speed relative to strength of proton motive force
bacterial flagella
counterclockwise
run
What is the difference of archaella from bacterial flagella?
smaller, proteins are unrelated and more similar to pili, move by rotation driven by ATP, generally swim much slower
What is flagella powered by?
PMF
movement typically occurs away from colony
surface motility
requires type IV pili
twitching motility
smooth, continuous motion along long axis without external structures, sometimes has a slime layer
gliding motility
response of ionic strength
osmotaxis
response to water
hydrotaxis
response to oxygen
aerotaxis
response to light
phototaxis
