Microbiology Ch. 4
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define prokaryote and eukaryote?
- Prokaryote- NO nucleus
- Eukaryote- nucleus
functional anatomy of Prokaryote?
- 1 circular chromosome not enclosed in membrane
- no histones
- no organelles
- peptidoglycan cell walls
- binary fusion division
what are histones?
what makes DNA coil and wrap up tight
Functional Anatomy of Eukaryote?
- paried chromosomes enclosed in nuclear membrane
- histones present
- organelles present
- polysaccharide cell walls
- mitotic cell division
basic shapes to prokaryote?
- Coccus- sphere
- Bacillus- rod
- Spirrila- spiral/cork screw
- wierd shapes: star shaped stella, square shaped haloarcula
average size of prokaryote?
0.2-1.0 um x 2-8 um
most bacteria are how many shapes?
monomorphic - meaning 1 shaped
a few bacteria can have multiple shapes which is defined as?
pleomorphic - multiple shapes
how are cocci arranged?
- Pairs - diplococci
- clusters- staphylococci
- chains- streptococci
how are bacilli attached to each other?
end to end, never in middle
arrangement of bacilli?
- pairs- diplobaccili
- chains- streptobacilli
- there is no staphylo arrangement in rods
shapes of spiral bacteria?
- vibro- comma shaped, only one bend
- spirilla- rigid, helical shape
- spirochetes- flexible, helical shape
name the outer structures?
- axial filament
characteristics of glycocalyx?
- outside cell wall
- usually sticky
- protects from dehydrations, and limit outward diffusion
how is glycocalyx organized?
- Organized (capsule)
- prevents phagocytosis
- composed of sugards to allow for attachment to surfaces
if the outer cell wall of cell is unorganized and loose what is it called?
if outer cell wall of cell is organized what is it called ?
during a negative stain what is the difference between capsules adn slime layers?
- capsules are more regular and organized looking
- slime layer are more diffuse and less organized
function of flagella?
characteristic of flagella?
- consist of chains of flagellin
- attached to a protien hook
- anchored to wall and membrane by basal body
- single- monotrichous
- on both ends- amphitrichous
- 2 or more on one or both ends- lophotrichous
- all over the cell- peritrichous
how do flagella move?
chemotaxis- directional movement according to chemical gradient. tumble and run. toward (attractant) or away (repellant)
phototaxis- movement according to light gradient
describe what tumble and run is?
flagella move in the direction of the attraction. the runs are longer (movement in 1 direction) and the tumble is less (stop and spin).
what are axial filaments?
- endoflagella - flagella on inside of cell
- located in spirochetes (create the spiral pattern of spiral bacteria)
- anchored at one end of cell
- rotation causes cell to move
what are fimbriae?
hairlike projections that allows for attachment so microbes can colonize.
what are pili?
- allow for transfer of genetic material from one cell to another.
- usually longer then fimbriae
- cells usually one have 1 or 2
describe the cell wall?
- determines the shape
- in some cases, recognized by host immune system
- target for antibiotics
- prevent osmotic lysis
- made of peptidoglycan (prokaryote)
gram positive cell wall?
- thick petidoglycan,
- teichoic acids,
- in acid fast cells, contain mycolic acid
- help regulare movement of cations
- polysacharides provide antigenic variation
gram negative cell wall?
- thin peptidoglycan ,
- no teichoic acids
- outer membrane
describe the extra outer membrane of gram negative cell wall?
- contains lipopolysaccharides
in gram positive cell wall what does techoic acid do?
- lipotechoic acid lins to plasma membrane
- wall techoic acids link to peptidoglycan
in gram negative cell wall what does lipopolysaccharides do?
barrier to antibiotics and surface molecules/antigens are useful in identification.
in gram negative, what does a strong negative charge protect from?
how gram stain works ?
- stain-crystal violet
- mordant- iodine
- alcohol -if gram positive-dehydrates or disolves peptidoglycan and crystal violet/iodine stuck inside cell
- if gram negative-alcohol dissolves outer membrane and leaves holes in peptidoglycan. the crystal violet and Iodine is washed out.
what does lysozymes and penicillin do to cell walls?
- lysozyme digests disaccharide in peptidoglycan
- penicillin inhibits peptide-bridges in peptidoglycan (why it is given to gram positive bacteria b/c they have more peptidoglycan )
characteristics of plasma membrane?
- fluid mosaic model- self healing puncture proof structure
- phospholipid bilayer
- contains peripheral, integral, transmembrane proteins
- selectively permeable
- enzymes for ATP production
- photosynthetic pigments on foldings called chromatophores or thylakoids
what damages plasma membrane?
- polymyxin antibiotics (neosporin)
types of movement across membrane?
- simple diffusion- movement from high to low concentration
- osmosis- water diffusion
- facilitated diffusion- transporter protiens
- active transport (against gradient)- transporter protiens/ATP
what is cytoplasm?
stuff inside plasma membrane
characteristics of cytoplasm?
- nuclear area has nucleoid
- free ribosomes
- inclusions- liquid, gas or other substances in cell
list of inclusions
- metachromatic granules
- lipid bubbles
- polysaccharide granules
- sulfur granules
- phosphate reserves
- energy reserves
- protien covered cylinders
- iron oxide reserves
what are endospores?
- resting cells
- durable, resistant form
- protect agains desiccation, heat and chemical
return to active form (vegetation state)
What would you like to do?
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