Stokes Microbiology Ch 4 (Prokaryotic)

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Why doesn't Penicillin harm human cells?

prokaryote ("prenucleus")

a cell whose genetic material (usually one circular chromosome) is not in a nuclear envelope, no histones (special chromosomal proteins), no membrane-enclosed organelles, peptidoglycan cell wall (if Bacteria), Pseudomurein cell walls (if Archaea, divide by *binary fission*; avg size: 0.2-1.0 µm x 2 - 8 µm

eukaryote ("true nucleus")

a cell whose DNA (in multiple, paired chromosomes) is found in the cell's nucleus (+*histones*), have membrane-enclosed organelles (ex/ mitochondria, ER, golgi complex, lysosomes), polysaccharide cell walls, divide by mitosis (have mitotic spindle)

binary fission

prokaryotic cell reproduction by the copying of DNA and division into two daughter cells; involves fewer structures and processes than eukaryotic cell division

mitosis

eukaryotic cell division in which chromosomes replicate and an identical set is distributed into each of two nuclei; process guided by mitotic spindle; two cells produced are identical to each other

cocci (singular: coccus), bacilli (singular: bacillus), spiral

basic shapes of prokaryotic cells:
1. spherical: _____
2. rod-shaped: _____
3. have one or more twists: _____

diplo-, staphylo-, strepto-

arrangements of cells (after dividing in planes)
paired: _____ | clusters: _____ | chainlike: _____ (bacilli only divide across short axis, so always chains/pairs) (Haloarcula ~ retangular, flat cells)

sarcina

a group of eight bacteria that remain in a packet after dividing

vibrios, spirilla, spirochete

Three kinds of spiral bacteria:
1. curved rods: ______; 2. have a helical, corkscrew shape and rigid bodies, use *flagella*: _____; 3. have a helical shape and flexible, have *axial filaments* contained within for movement: _____

pleomorphic, monomorphic

______: have many shapes, ______: maintain a single shape

glycocalyx (prokaryotic)

a viscous, gelatinous polymer surrounding a cell, composed of polysaccharide/polypeptide/both; made inside cell wall and secreted to surface; (organized and firmly attached: *capsule*; unorganized and loosely attached: *slime layer*)

capsule

_______: neatly organized, firmly attached glycocalyx, outside cell wall, protects pathogenic bateria from phagocytosis (ingestion and degestion of microbes) of immune cells, produce mucoid (stick) colonies on agar

slime layer

_______: unorganized, loose glycocalyx; protects cells from loss of water or nutrients, role in biofilm (*EPS* [extracellular polymeric substance]: helps cells attach to target environment and to each other, protects)

flagella

long filamentous appendages that propel bacteria; outside cell wall; attached to a protein "hook"; anchored to the wall and membrane by *basal body*; (prokaryotes' "filament": chains of flagellin (protein), eukaryotes: 9 +2 microtubles)

peritrichous, polar, atrichous

arrangements of bacterial flagella:
1. ______: distributed over the entire cell
2. ______: at one or both ends of the cell

bacteria without flagella ("without projections"): _____

mono-, lopho-, amphi-

arrangements of bacterial flagella that is polar:
1. ____-trichous: a single flagellum at one pole
2: ____-trichous: a tuft of flagella coming from one pole
3. ____-trichous: flagella at both poles of the cell

basal body, - (negative), + (positive)

____ anchors flagellum to cell wall and plasma membrane, composed of a small central rod inserted into a series of rings;
gram ____:two pairs of rings, outer ring anchored to cell wall, inner ring to plasma membrane; gram _____: only inner pair

rotate, undulate

prokaryotic flagellum (semirigid, helical) movement: ______ from basal body, run and tumble;
eukaryotic flagellum movement: ______ in wavelike motion

taxis

the movement of a bacterium toward or away from a particular stimulus
ex/ chemicals (*chemo-*), light (*photo-*)

H antigen

the flagellar protein, which is useful for distinguishing among *serovars* (variations) of gram-negative, pathogenic bacteria

axial filaments (*endoflagella*)

the structure (made of bundles of fibrils) for motility in spirochetes, anchored at one end of the cell, beneath outer sheath, causes movement with rotation (like a corkscrew through a cork);
(how T. pallidum [syphilis] moves effectively through body fluids)

fimbria (plural: fimbriae)

bacterial cell appendage used for attachment, shorter, straighter, thinner than flagella, consist of protein "pilin", can occur at the poles or evenly distributed over surface; involved in forming biofilms, etc.;
(enables E. coli to adhere to small intestine lining)

pilus (plural: pili)

an appendage on a bacterial cell used for *conjugation*/DNA transfer and motility (*gliding*/*twitching*); consist also of pilin; usually longer than fimbriae; only one or two per cell;

twitching

____ motility: pilus extends by addition of subunits, makes contact, then retracts (powerstrokes) and disassembles, results in short/jerky/intermittent mvmts (grappling hook)
_____ motility: smooth mvmt of myxobacteria, for travel in low water content (biofilms/soil)

cell wall (bacterial)

complex, semirigid structure responsible for cell shape; made of *peptidoglycan*; prevents osmotic *lysis*; point of flagella anchorage; contributes to ability to cause disease and site of action of some antibiotics

peptidoglycan

the structural molecule of bacterial cell walls, present alone or in combo with other substances; a repeating disaccharide (NAG+NAM backbone) attached by *polypeptides* that forms lattice that surrounds/protects the entire cell.

lysis

destruction to cell caused by rupture of the plasma membrane and loss of cytoplasm

positive

gram-____ bacteria: have a thicker peptidoglycan cell wall, teichoic and lipoteichoic acids; CV-I complex (purple) does not wash out, tend to be killed by penicillin, lysozyme, detergents

negative

gram-____ bacteria: layer of lipopolysaccharide within their cell wall, thin peptidoglycan (bonded to lipoproteins) in the periplasm (which has degradative enzymes, transport proteins), more resistant to antibiotics, destroy with alcohol easier

teichoic acid

acid in gram+ cell walls that consists primarily of an alcohol and phosphate; may bind/regulate mvmt of cations in/out; role in cell growth; polysaccharides provide antigenic variation;
two classes: 1. lipoteichoic: links to plasma membrane 2. wall teichoic: links to peptidoglycan

outer membrane (of a gram-negative cell)

cell part that consists of lipopolysaccharides, lipoporoteins, phoscholipids; strong negative charge (protection from phagocytosys and complement actions); barrier to antibiotics (penicillin), digestive enzymes (lysozyme/detergents/heavy metals/certain dyes)

porin

protein in the outer membrane of a gram-negative cell wall that form channels through the membrane, permitting the passage of small molecules

LPS (lipopolysaccharide)

large complex molecule of gram-negative cell's *outer membrane* that consists of 1. *lipid A* (lipid portion in membrane's top layer that is released as an endotoxin when the cell dies) 2. *core polysaccharide* (stability) 3. *O polysaccharide* (antigen) ex/ E. coli

mycoplasma

genus whose members are the smallest known bacteria that can grow and reproduce outside living host cells; no cell walls; very small; plasma membranes have *sterols* (lipids)

Archaea

cell that may lack cell walls or have walls of *pseudomurein* (not peptidoglycan, so it lacks NAM and D-amino acids found in bacterial cell walls); can not be gram-stained but appear gram-negative because no peptidoglycan

mycolic acid

a hydrophobic waxy lipid in high concentrations (60%) in the cell walls of all bacteria of Mycobacterium and Nocardia; bound to peptidoglycan by a polysaccharide; stained with carbolfuchsin; if removed, acid-fast bacteria stains gram+

lysozyme

enzyme that occurs naturally in eukaryotes, a constituent of tears/mucus/saliva; makes gram+ bacteria vulnerable to lysis (digests disaccharide in peptidoglycan, almost completely destroys cell wall)

protoplast

a wall-less gram-positive cell; a gram+ cell treated to remove the cell wall; typically spherical and capable of carrying on metabolism; susceptible to *osmotic lysis*

L form

prokaryotic wall-less cell that swell into irregular shapes, can form spontaneously or develop in response to penicillin/lysozyme; can live/divide repeatedly or return to the walled state

penicillin

antibiotic which inhibits cell wall formation (by inhibiting peptide bridges in peptidoglycan); especially to gram+ cells because gram- cells have an outer membrane that protects

spheroplast

a wall-less gram-negative cell; a gram- cell treated to remove the cell wall; a spherical structure; gram- cells first treated with EDTA to weaken outer membrane before lysozyme; susceptible to osmotic *lysis*

plasma (cytoplasmic) membrane

prokaryotic selectively permeable membrane enclosing cytoplasm of a cell, internal to the cell wall; a *phospholipid bilayer* (polar heads, nonpolar tails), *peripheral*/*integral* proteins; viscous like olive oil: *fluid mosaic model*

peripheral, integral

____ proteins lie at the inner or outer surface of a plasma membrane; function as enzymes, for support; ____ proteins penetrate the membrane (can be removed only after disrupting the lipid bilayer); *transmembrane proteins* go completely through; functions as channels for entrance/exit

glycoprotein, glycolipid

____ is a protein attached to a carbohydrate, ____ is a lipid attached to a carb; both help protect and lubricate the cell

fluid mosaic model

a way of describing the dynamic arrangement of phospholipids and proteins comprising the plasma membrane (not static); membrane is viscous like olive oil, proteins move freely enough to function; phospholipids rotate and move laterally

selective permeability, energy

functions of the plasma membrane:
1. ____ ______: allows only certain molecules/ions to enter/exit; 2. enzymes for ATP production (____); 3. photosynthetic pigments in its folds: *chromatophores*/*thylakoids*

leakage of cell contents

alcohols, quaternary ammonium (detergents/disinfectants), and polymyxin antibiotics damage the plasma membrane by causing _____ __ ___ _____

passive transport

movement across the membrane from a higher to a lower concentration (with the concentration gradient) without energy (ATP)
includes: *simple diffusion*; *facilitated diffusion*, *osmosis*

active transport

movement across the plasma membrane from a lower to a higher concentration (against the concentration gradient), requires energy (ATP) and transporter proteins

simple diffusion

the net (overall) movement of molecules/ions across a membrane from an area of high concentration to an area of low concentration until it reaches equilibrium; for transport of certain small molecules

facilitated diffusion

movement of a substance across a plasma membrane from high to low concentration, mediated by *transporter proteins* (integral proteins); the solute combines with a non/specific transporter, sometimes large molecules broken down by "extracellular enzymes" beforehand

osmosis

movement of water (solvent molecules) across a selectively permeable membrane from high water concentration to low water concentration; water molecules pass through by simple diffusion or through "aquaporins* (integral proteins=water channels)

osmotic pressure

the pressure needed to stop the movement of pure water across the membrane; the force with which a solvent moves from a solution of lower solute concentration to a solution of higher solute concentration

isotonic (solution)

kind of osmotic solution in which the overall concentration of solutes outside equals the concentration found inside a cell; water leaves and enters at the same rate; contents in equilibrium

hypotonic (solution)

kind of osmotic solution in which the concentration of solutes outside the cell is lower than the concentration of solutes inside (water tries to go in, which may cause osmotic lysis)

hypertonic (solution)

kind of osmotic solution in which the concentration of solutes outside the cell is higher than the concentration of solutes inside (water tries to come out, which may cause shrinkage/*plasmolysis*)

group translocation

a special form of active transport that occurs exclusively in prokaryotes where a substance is chemically altered during transport across the membrane (therefore cannot exit again); requires transporter protein and PEP (phosphoenolpyruvic acid, a high-energy P compound)

cytoplasm

substance inside the plasma membrane; thick, aqueous, semitransparent, elastic gelatinous solution containing 70-80% water, nutrients, proteins, genetic membrane; site for cell metabolism, biochemical, and synthetic activities

nucleoid

the region in a bacterial cell containing *bacterial chromosomes* (the cell's genetic material) and *plasmids* (extra-chromosomal DNA, can be advantageous but not necessary)

ribosome

the site of protein synthesis in a cell, composed of RNA and protein; the prokaryotic kind: *70S* (small 30S subunit containing 1 rRNA + larger 50S subunit containing 2 rRNA)

inclusions

material held inside a cell, often consisting of reserve deposits/storage for nutrients (ex/ to save for when environment is deficient, to store gases for buoyancy)

volutin (metachromatic granules)

large inclusions: phosphate reserves;

characteristic of diphtheria, of diagnostic significance

energy reserves

*polysaccharide granules*, *lipid inclusions*, and *sulfur granules* are inclusions that serve as _____ ______.

carboxysome

a prokaryotic inclusion containing ribulose 1,5-diphosphate carboxylase for CO2 fixation

gas vacuole

a prokaryotic inclusion for buoyancy compensation (so can remain at appropriate depth in water), consist of several individual vesicles

magnetosome

an iron oxide inclusion, produced by some gram-negative bacteria, that acts like a magnet (to move downward towards an attachment site, can decompose hydrogen peroxide)

endospore

special resistant, resting structure within a cell formed when essential nutrients in gram+ bacteria are depleted; can survive extreme heat, lack of water (desiccation), toxic chemicals, radiation

sporulation (sporogenesis)

the process of endospore formation within a vegetative cell; takes several hours; begins when key nutrient becomes scarce; when endospore matures, the original vegetative cell wall ruptures and kills the cell; not a means of reproduction

germination

a process in which an endospore returns to its vegetative state; triggered by physical/chemical damage to the endospore's coat--enzymes break down surrounding layers, water enters, metabolism resumes

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