Term
|
Definition
o 0.2 – 3um in diameter
o No membrane around genetic material or organelles
o Examples
§ Bacteria
§ Archaea |
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|
Term
|
Definition
o 10-100um in diameter
o Membrane bound nucleus and organelles
o Complex cytoskeleton
o Examples
§ Fungi
§ Protozoa
§ Algae
§ Helminths |
|
|
Term
Size, shape, and arrangement of Prokaryotic cells
|
|
Definition
o 3 basic shapes
§ Cocci (coccus, singular) – spherical/round
§ Bacilli (bacillus) – rod
§ Spiral – curved/twisted
o Wide variety of shapes and sizes within each category
§ 0.2 – 3.0um in diameter
§ 0.5 – 10um in length
§ Cell arrangement depends on
· How quickly divided cells separate
· How many planes they divide in |
|
|
Term
Cocci: Size, Shape and Arrangement |
|
Definition
o Cells round, ellipsoid, or bean shaped
o Arrangement depends on species
§ One plane division – single cells, pairs, or chains (streptococci)
§ Two plane division – tetrads
§ Three perpendicular plane division – Groups of 8 (sarcinae)
Random – bunches (staphylococci |
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|
Term
Bacilli: Size, Shape, and Arrangement |
|
Definition
o Individual cells can be
§ Short (coccobacilli)
§ Long
§ Thin
§ Fat
§ Filamentous
o And can have ends that are
§ Square
§ Rounded
§ Ellipsoid
§ Spindle-shaped (fusiform)
o Arrangement depends on species
§ Single cells
§ Pairs of cells
§ Chains
o Corynebacterium – Form V, Y, and palisade (zigzaggy) shapes by a snapping division process
o Actinomyces – form long branched filaments that can break up into rod and Y shapes
o Mycoplasma – lack cell walls and are pleomorphic (variable shapes) |
|
|
Term
|
Definition
| Bacilli Example with form of V, Y, and palisade (zigzaggy) shapes by a snapping division process |
|
|
Term
|
Definition
| Bacilli with form of long branched filaments that can break up into rod and Y shapes |
|
|
Term
|
Definition
| Bacilli that lack cell walls and are pleomorphic (variable shapes) |
|
|
Term
· Spiral Bacteria: Size, Shape, and Arrangement |
|
Definition
o Three groups
§ Vibrios – Comma shaped rods
§ Spirilla – Rigid spiral shapes
§ Spirochetes – flexible corkscrews |
|
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Term
|
Definition
o Glycocalyx
o Flagella
o Fimbriae
o Sex pili
o Cell wall |
|
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Term
|
Definition
o Thick gelatinous polymer covering cell
o Some don’t produce glycocalyx
o Mostly polysaccharides, sometimes proteoglycans
o Two types
§ Capsules – Thick, discrete, inseparable coat
§ Slime layer – Loosely formed around cell and separable
o Coats are virulence factors
§ Interfere with phagocytosis
§ Prevent desiccation – enhances survival outside of host
§ Adhesins – allow to attach to inert surfaces
§ Initiate biofilms on implanted devices |
|
|
Term
Catheter-Induced Infections
|
|
Definition
o Staphylococci on skin attach to implanted catheters
o Attachment triggers sticky slime layer production
o Slime layer initiates biofilm which migrates into tissue
o Most common infection acquired in hospitals – catheters need to be replaced every 2 days
|
|
|
Term
|
Definition
o Artificial heart valves, hips, knees all subject to attachment by staphylococci
o Attachment stimulates sticky slime layer and biofilm formation
§ Biofilms on artificial heart valves → infective endocarditis
§ Biofilms on artificial hips and knees → inflammation, bone resorption, failure. 25% chance another will be successful and the patient will walk |
|
|
Term
|
Definition
o Bacteria on teeth form biofilms and ferment sugars to acids → caries
o Also produce products causing gingival inflammation and periodontal disease
|
|
|
Term
· Capsular strain variation |
|
Definition
o Some pathogens have many different strains with chemically and antigenically different capsules
o Variation affects host’s ability to develop immunity
o Streptococcus pneumoniae – 90 distinct types
o Antibodies are capsule-specific
o After antibodies bind, phagocytes bind to antibodies (opsonization) and kill antigen
o S. pneumoniae spontaneously form acapsular variants
§ Rough on media
§ Avirulent
o Smooth are virulent |
|
|
Term
|
Definition
o 3 Parts
§ Long filament
§ Hook (adaptor)
§ Basal body
o 12-20nm diameter
o Consist of flagellin protein monomers
o Dissociate at pH 3
o Reassociate at pH 7
o Hook – attaches filament to basal body
o Basal body – embedded in cell wall and turns like turbine
§ Proton motive force (H+ passing through channels and rotating)
o Number of and location of flagella species specific and used in identification
o 4 Arrangements
§ Monotrichous – Single
§ Lophotrichous – Two or more at one end
§ Amphitrichous – One of more flagella at each end
§ Peritrichous – Multiple flagella everwhere |
|
|
Term
|
Definition
o Motile bacteria can move toward and away from stimulants (taxis)
§ Phototaxis – light is stimulant
§ Chemotaxis – chemical concentrations
o Can change directions by reversing flagella rotation
o Counterclockwise flagella rotation – straight line (run) while flagella wrap and rotate as one
o Clockwise – flagella fly apart and cell tumbles
o No chemoattractant – random
o Chemoattractant present – cell moves up gradient
§ Higher gradient à more binding to receptors à longer runs
§ Lower gradient à less binding to receptors à more tumbling
§ Process: Run, tumble, run, tumble |
|
|
Term
· Axial Filaments (Endoflagellum)
|
|
Definition
o Convey motility to spirochetes
o Fibrils at each end spiraling around under sheath à corkscrew motion |
|
|
Term
|
Definition
o Fimbriae and pili used to be interchangeable and refer to nonmotile bristle-like structures
o Sticky, non-motile, bristle-like filaments on surface
o Thinner, straighter, shorter, more numerous than flagella (100-200 per cell)
o Mediate attachment to surface, or other cells
§ Essential virulence factors due to adhesive properties
o Adhesins – substances facilitating attachment
§ Glycocalyx – better for attachment to inert surfaces
§ Fimbriae – better for attachment to host cells and tissues
o Fimbriae can be lectins
§ Bind to specific sugar of glycoprotein
§ Lectins agglutinate (clump) red blood cells
§ Specific sugar identified because when added, lectins do not agglutinate RBCs
o Antigenic variation – ability to vary antigenic type of fimbriae
§ Allows pathogen to evade immune responses – new fimbrial antigen every 2 weeks
§ Hosts take 2 weeks to create antibodies – by that tame antigen factor changed
§ Example: Neisseria gonorrhoeae
· Capable of hundreds of distinct fimbriae by recombining genes for protein subunit
· Changes every 2 weeks
· No immunity developed – 1 million new cases each year
§ Can also occur with flagella and other surface proteins
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|
|
Term
|
Definition
o Long hollow tubular structures allowing Gram-negative bacteria to transfer DNA in conjugation
o Like fishing rod (pole and hook)
o Once other cell caught, disassembles cytoplasmic subunits and reels in cell till cell-cell contact
o Pilus-positive cells (F+) produce only a few per cell
o Made of self-aggregating protein monomer called pilin
o Major mechanism for gram-negative genetic diversity
o Facilitates transfer of antibiotic resistance
o Gram-negative leading cause of nosocomial (hospital-acquired) infections
§ Often caused by bacteria with multiple genes for antibiotic resistance on plasmids from conjugation |
|
|
Term
· Most prokaryotes have cell wall that provides
|
|
Definition
o Shape
o Structure
o Protection against osmotic pressure
|
|
|
Term
Cell walls of bacteria and archaea different
|
|
Definition
o Bacteria – Peptidoglycan,
o Archaea – No Peptidoglycan
|
|
|
Term
|
Definition
| (bacteria) – Few with no cell wall |
|
|
Term
|
Definition
o Gram-positive and Gram-negative both have peptidoglycan
o Gram-positive
§ Single, thick, layer of peptidoglycan and other polymers
§ Adjacent and external to cytoplasmic membrane
§ See figure 3b-3
o Gram-negative
2 distinct layers
§ Outer membrane layer
§ Thin inner later of peptidoglycan
§ (Cytoplasmic membrane)
§ See figure 3b-4 |
|
|
Term
|
Definition
o Large, crosslinked polymer that maintains
§ Shape
§ Structural rigidity
§ Protection against osmotic lysis
o Long polysaccharide chains
§ Crosslinked by peptide bridges
§ See Figure 3b-5
§ Alternating ß-D-N-acetylglucosamine and ß-D-N-acetylmuramic acid residues connected ß (1-4) linkages with between acetylmuramic acid
o Amino acids in peptide bridges vary by species but assembled from basic pentapeptide
§ L-alanine, D-isoglutamamide, L-lysine, D-alanine, D-alanine
§ Contains D-alanine and D-isoglutamamide
§ Diamino in pos 3 can be lysine, ornithine, or diaminopimelic
o Terminal D-alanine lost in transpeptidation of adjacent side chains (at acetylmuramic acid)
§ Link between Carboxyl at 4th peptide (D-alanine) and side chain amino group of 3rd peptide on adjacent chain
§ Some gram-positive have extra amino acids in crosslink (interbridge)
§ Degree of crosslinking varies by species
· Staph aureus – 100%
· Escherichia coli – 70%
o Peptidoglycan AKA murein
o Ideal target for antibiotics since only found in bacteria |
|
|
Term
Peptidoglycan and Antibiotics |
|
Definition
o Peptidoglycan disruption antibiotics harmless to eukaryotes
o Antibiotics interfering with peptidoglycan synthesis
§ Examples
· Penicillin
· Cephalosporins
· Vancomycin
§ Inhibit crosslinking à defective walls à lyse in hypotonic solutions |
|
|
Term
Enzymatic breakdown of peptidoglycan |
|
Definition
o Hydrolyzed by
§ Lysozyme – hydrolyzes N-Ac-Mur-ß-(1,4)-N-Ac-Glc bond
§ Endopeptidases – hydrolyze peptide bridges (crosslinks)
§ Amidases – hydrolyze linkage between N-Ac-muramic acid and L-alanine
o Lysozyme can be used to prepare
§ Protoplasts – cell wall-less gram-positive
§ Spheroplasts – cell wall-less gram-negative
§ Both must be kept in isotonic solutions or lysis occurs
|
|
|
Term
|
Definition
o Present in most human tissues
§ Degrades peptidoglycan causing bacteria to lyse
§ Used by phagocytes
o Some gram-positive mutate to be lysozyme resistant by either
§ OH groups on muramic acid
§ Removing N-acetyl group from N-Ac-glucosamine |
|
|
Term
|
Definition
o Single thick layer of peptidoglycan
o Strong, but porous to chemicals <1000 daltons
o 30 murein chains thick
o 50-90% of cell dry weight
o Include proteins, polysaccharides, and/or lipids
§ Covalently attached to peptidoglycan or anchored in cytoplasmic membrane
§ Pass through cell wall and stick out
o All have polysaccharide polymer called teichoic or similar teichuronic acid |
|
|
Term
|
Definition
o Only in gram-positive
o Essential
o Function unknown but may regulate cell separation or store metal ions and sugars
o Long, linear (ribitol-phosphate)n or (glycerol-phosphate)n (n=20-30) polymers
§ Hydroxyl groups of sugars often replaced with D-alanine or a sugar
o Ribitol teichoic acids—wall teichoic acids
§ Covalently linked to OH group on C-6 of N-ac-muramic acid
o Glycerol teichoic acids – lipoteichoic acids
§ Covalently linked to glycolipid in cytoplasmic membrane |
|
|
Term
|
Definition
Phosphate deficiency in medium à acidic sugars like glucouronic acid substitute for phosphate.
May regulate cell separation at growth or serve as storage polymers for metal ions and sugars |
|
|
Term
Resistance to degradation of gram-positive bacteria |
|
Definition
o Group A streptococcus covered with M-protein à not easily degraded
§ Intravenous injection à inflammation, arthritis, and rheumatoid nodules
o Mycobacterium tuberculosis has outer layer of arabinogalactan and waxy lipids called mycolates à resistant to macrophages
§ Causes tuberculosis when poor cellular immunity |
|
|
Term
· Gram-Negative Cell Walls
|
|
Definition
o Two distinct layers
§ Outer membrane layer composed of
· Lipopolysaccharide
· Proteins
· Phospholipids
§ Inner layer
· Thin layer of peptidoglycan
· Few saccharide chains in thickness
· Not fully cross-linked
o Cytoplasmic membrane internal and adjacent to peptidoglycan layer
o Space between membranes called periplasmic space
o Anchor lipoprotein
§ Helical
§ Small (7500 daltons)
§ Covalently attached to one of every 10 tetrapeptide units
· Between carboxyl terminus of lipoprotein and side amino group of diamino acid at pos 3 in tetrapeptide unit
§ Lipid portion embedded in inner leaf of outer membrane
§ Anchors inner and outer layers of cell wall
o Less peptidoglycan à less rigid and strong than gram-positive |
|
|
Term
Lipopolysaccharide (LPS) Structure |
|
Definition
o Unique, complex glycolipids with three covalently linked parts
§ Lipid A
§ Core polysaccharide
§ O-specific polysaccharide chain or O-antigen
o Lipid A and core polysaccharide similar in all gram-negatives
o O-antigen different for each gram-negative species |
|
|
Term
|
Definition
o Large, complex, unusual glycolipid
o Embedded in outer leaf of outer membrane of gram negative bacteria
o Large size and numerous saturated fatty acids make outer membrane more rigid than normal |
|
|
Term
|
Definition
o Links lipid A to O-specific polysaccharide
o Contains
§ 8 carbon sugar – 2-keto-3-deoxyoctulosonic acid (KDO)
§ 7 carbon sugar – L-glycero-D-mannoheptose
§ Other sugars
o General structure
§ [KDO-Heptose-Other sugars]
o Mutants lacking
§ KDO à can’t grow
§ Seven carbon sugarà functional deficiencies but survive
§ Other sugars à form atypical rough ® colonies instead of smooth, but normal |
|
|
Term
| O-Specific Polysaccharide Chain |
|
Definition
o Long polymer extending out from membrane
o Attached to terminal sugar of core polysaccharide
o 3-5 sugars repeating 10-50 times
o Contains unusual sugars
§ Dideoxyhexoses
§ Aminohexuronic acids
§ Deoxyaminohexoses
o Major surface antigen of gram-negative bacteria
o Different for each species and even strains
o Called O-specific antigen or O-antigen
o Variation of Salmonella typhurium
§ 2000 strains each with different O-antigen
§ Immunity only develops to specific strain
§ Can get over and over, and vaccine impossible |
|
|
Term
|
Definition
o LPS highly toxic to mammals AKA endotoxins
o Lipid A moiety is toxic component
o Signs and symptoms
§ Sublethal - <100ug à Fever, edema, low blood pressure and aches and pains
§ Lethal - >100ug àFever, edema, low blood pressure, shock, intravascular coagulation, loss of consciousness, circulatory collapse, organ failure and death within hours of first symptoms
o Endotoxin poisoning happens when gram-negative bacteria enter bloodstream and multiply – septicemia
§ Release endotoxins from cell wall as they grow
§ 80,000 cases of gram-negative septicemia each year in US
§ Difficult to treat
§ High fatality (25%) even in hospital
§ Antibiotics sometimes exacerbates by causing lysis and endotoxin release
o Also concern in pharmaceutical
§ Pyrogens – cause fever
§ Trace amounts even 1 nanogram injection of endotoxin causes fever
§ Most things are cominated with trace endotoxins because gram-negative bacteria are everywhere
§ Even if sterile, need to be tested for pyrogens
§ Autoclaving doesn’t destroy endotoxins
§ Must be filtered or distilled
§ Horseshoe crab (limulus lysate) tests for endotoxins by clotting in presence of trace amounts
§ Or inject in rabbit and measure fever
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|
|
Term
Proteins and phospholipids in Gram-Negative Cell Walls |
|
Definition
o Inner leaf of outer membrane mainly phospholipids
o Proteins
§ Major component – Porin, a channel forming protein allowing small nutrients to pass
§ Lipoprotein – attached to every 10 tetrapeptides in peptidoglycan and anchoring layers of cell wall
§ Periplasmic space and Cytoplasmic membrane contain other nutrient transport proteins |
|
|
Term
Practical Consequences of Gram-Negative Cell Walls
|
|
Definition
o LPS is large and solid
§ Makes outer membrane rigid and not easily penetrated by hydrophobic compounds
§ Resistant to detergents since they cannot penetrate
o Porin makes outer membrane permeable to small hydrophilic compounds <600 daltons
§ Resistant to many antibiotics and inhibitory dyes due to being too large for porin
o More susceptible to osmotic lysis due to thinner peptidoglycan wall |
|
|
Term
Proteins and phospholipids in Gram-Positive Cell Walls
|
|
Definition
o Small molecules <1000 daltons can penetrate through porous cell wall
o Sensitive to many antibiotics and inhibitory dyes |
|
|
Term
Bacteria without cell walls |
|
Definition
o Mycoplasma is a genus of bacteria without cell walls
o L forms are laboratory produces mutant bacteria without cell walls |
|
|
Term
|
Definition
o Not well characterized
o Polysaccharides and proteins but no peptidoglycan
o Cell wall polymer – pseudomeurein
o Some stain gram-positive, some gram-negative |
|
|
Term
|
Definition
o Prokaryotes contain proteins
Eukaryotes glycoproteins
A selectively premeability barrier
|
|
|
Term
|
Definition
o Phosphoglycerides
o Sphingolipids
o Sterols |
|
|
Term
|
Definition
o Amphipathic lipid w/
§ Glycerol core
§ Two long hydrocarbon chain tails
§ Hydrophilic alcohol head
o Most common lipid in membranes
o Structurally heterogenous
o Fatty acyl chains connect to OH of phosphoglycerol via ester linkages
o Alcohol attaches to PO4 group
o Variety of alcohol and fatty acyl chains
§ Most common alcohols
· Ethanolamine
· Choline
· Serine
· Inositol
· Glycerol
§ Most common fatty acyl chains
· 16 & 18 carbon saturated, mono-unsaturated, and di-unsaturated
o Plasmalogens – One fatty acyl by ester, one by ether
o Phosphoglycerol diethers – Both fatty acyls by ether
o Diphosphoglycerol tetraethers – Glycerol at both ends via ether linkages
o Phosphoglycerol diethers and diphosphoglycerol tetraethers found in archaea |
|
|
Term
|
Definition
o Amphipathic lipids derived from sphingosine (amino alcohol with long hydrocarbon tail
o Only found in eukaryotic cells
o Sphingomyelin – phosphocholine attached to sphingosine’s terminal hydroxyl group, and a fatty acid to its amino group
o Glycosphingolipids – one or more sugar to sphingosines terminal OH group and fatty acid to amino group
o 2 – 10 % of lipids in eukaryotic cell membranes and localize in lipid rafts |
|
|
Term
|
Definition
o Rigid 4 ring hydrocarbon compounds
o Constitute 25% of lipids in eukaryotic cell plasma membranes
o Variety in membranes
§ Animals – cholesterol
§ Fungi – Ergosterol
§ Plant – Stigmasterol
o Bacteria (except Mycoplasma) and archaea don’t have sterols in plasma membrane
§ Some have hopanoids in membrane, sterol like lipid |
|
|
Term
Structure of Biological membrane |
|
Definition
o Lipid bilayer
o Embedded proteins
o Each layer – leaflet
o Basic components
§ Phosphoglycerides
§ Sphingolipids
o Auto aggregate tail to tail
o Diphosphoglycerol tetraethers à very stable lipid monolayer found in extreme thermophile archaea
|
|
|
Term
Physical Properties of Biological Membranes
|
|
Definition
o Under physiological conditions
· Low viscosity fluid state like light oil
· Lipids move laterally but cannot change leaflets
· Fluid mosaic model
o Membrane fluidity varied by lipid composition
§ Cells can vary saturated versus unsaturated fatty acyl chains
· Lower temp more unsaturated
· Higher temp more saturated
o Eukaryotes can add sterols
§ Make membrane more rigid at high temps
§ Keep sphingolipids and phospholipids from packing too tightly at lower temps |
|
|
Term
|
Definition
o 18% to 76% of membranes by weight
§ Prokaryotes cytoplasmic membrane – 70% protein and 30% lipids
§ Eukaryotes cytoplasmic membrane – 50% protein 50% lipids
o Some proteins span membrane, others in one leaflet
o Move laterally but not from leaflet
o Functions
§ Transporters
§ Anchors
§ Receptors
§ Enzymes
§ Adhesins
§ Signalling
§ Recognition |
|
|
Term
Differences in cell membranes |
|
Definition
o Bacteria, archaea, and eukaryotes use different lipids in forming cytoplasmic membranes
o Bacteria
§ Most simple phosphoglycerides only
§ Sphingolipids and sterols only added in Mycoplasma
§ Some bacteria have hopanoids – sterol like lipids
o Archaea
§ Phosphoglycerol diethers or diphosphoglycerol tetraethers with branched hydrocarbon side chains
§ Branched hydrocarbon chains from 5 carbon monomer isoprene
§ Phosphoglycerol dietheres work like phosphoglycerides but ether more resistant to hydrolysis than esters
§ Diphosphoglycerol tetraethers – phosphoglycerol to each end of 2 long branched hydrocarbon chains (often 40 carbon diphantyl) via ether linkages
· Extreme thermophiles
· Lipid monolayer
o Eukaryotes
§ Phosphoglycerides
§ Sphingolipids
§ Sterolds
o Prokaryotic membranes perform much function of eukaryotic organelles and have proteins for
§ Aerobes and facultatively anaerobic bacteria contain – respiratory electron transport chain
§ Photosynthetic bacteria – photosynthetic enzymes
§ Cell division
§ Cell wall precursor synthesis
o Membrane folds back on itself in invaginations called mesosomes
§ Could contain ETC
§ Could be artifact
o Cytoplasmic membranes destroyed by
§ Alcohols
§ Quaternary ammonium compounds
§ Detergents
§ Antibiotics called polymyxin |
|
|
Term
Nutrient transport across membrane
|
|
Definition
o Pure phospholipid impermeable to hydrophilic compounds but they need them to live
§ Overcome by transport proteins
§ Makes chemical gradients possible
o Concentration gradient – chemical inequality
o Charge gradient – charge inequality
§ 70mV across cytoplasmic membrane
§ Cytoplasm contains large negatively charged molecules (proteins, nucleic acids)
· Cannot escape
· Need to be counterbalanced by positive charges in cell
· Do so with high K+ concentration in cells
· Sodium potassium pump
o Uses ATP to pump K+ in and Na+ out
o Membrane freely permeable to K+ but not Na+
o High concentration inside vs out (140mM/4mM) causes K+ to sneak out, leaving – charge inside
o – charges on inside attract + charges outside
§ Oppose K+ leaking out
o Eventually K+ attracted to negative charge inside
o K+ leaks until electrical gradient force equals chemical gradient force
o -70mV
o Called Electrochemical gradient
§ Used to transport substances across membrane
o Certain drugs (digitalis) inhibit Na K pump and lessen gradient à contractions come easier and more forcibly. usead to treat congestive heart failure
§ Foxglove naturally does this – medicine and poison |
|
|
Term
Group transport – Active transport process
|
|
Definition
o Only in prokaryotes
o Substrate gradient created by phosphorylating substance being brought into cell
o Phosphorylated form unable to cross back
o Phosphoenolpyruvate-sugar phosphotransferase system (PEP-PTS)
§ Transports sugar into cells
§ Membrane bound proteins transfer phosphate from PEP to sugars transported into cell
§ Internal sugars not affected
§ Highly efficient and rapid system used to take up sugar
§ Effective at low sugar concentrations such as 1 ppm
§ Dental plaque use PEP-PTS to take up sugars in oral cavity
· Only fed several times a day
· Have to take up sugar rapidly
· Figure 3c-45 shows one tooth bathed in sugar solution and stained or sugar to see how plaque uptakes sugar
· Microscopic observation shows new polysaccharies inside bacteria (especially streptococci)
· Virulence factor for denatl caries because it allows acid production for prolonged periods of time.
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|
|
Term
Prokaryotic Non-Membranous Organelles
|
|
Definition
o Cytoskeleton
§ Network of protein fibers in cytoplasm
§ Some prokaryotes don’t have one, some have simple
§ Cocci do not have it
§ Rod and spiral shaped cells usually have cytoskeleton of actin-like protein
§ Eukaryotes have complex cytoskeleton
o Ribosome
§ Large non-membranous organelles that synthesize proteins
§ Thousands in one prokaryote
§ Size in svedberg (S) units – rate of sedimentation in centrifuge
§ Prokaryotes – 70 S (smaller)He said know these 70s and 80s numbers and what they mean
§ Eukaryotes – 80 S (larger)
§ Subunits
· 30 S and 50 S
· each contains proteins and rRNA |
|
|
Term
Prokaryotic Inclusion Bodies |
|
Definition
o Large granules or storage deposits in cytoplasm
o Variety of purpose eg. Energy reserve
§ Glycogen
§ Starch
§ Sulfur granules
§ Gas vacuoles
o Gas vacuoles allow to float where light reaches |
|
|
Term
|
Definition
o Highly resilient resting structures to survive adverse conditions
o Resistant to killing by chemical and physical agents than normally sterilize
§ Not killed by heating or boiling
§ Need 121 degrees C moist heat at 15 PSI for 15 min (autoclave or pressure cooker)
o Resistant to staining – have to be stained while heated and have a detergent
o Resilience
§ Little to no water or cytoplasm
§ Multiple layers of dipicolinic acid – calcium chelator only in bacterial endospores
o Virulence factor for endospore forming pathogens
§ Bacillus anthracis à anthrax
· Viable in soil for centuries
· Slaughtering and burn carcasses, quarantine land, wait till not infective |
|
|
Term
|
Definition
o Sporulation
o See Figure 3c – 55 (He said he does not ask detaqils about this)
§ DNA divides and aligns along cell axis
§ Membrane invaginates and forms forespore
§ Forespore covered in another cytoplasmic membrane, other DNA degrades
§ Cortex of calcium and dipicolinic acid deposited between membranes
§ Spore coat forms
§ Endospore matures by unknown process (increases resistance)
§ Released from cell
o Takes 4-8 hrs to form
o One cell à one endospore (KNOW) and that it is not a reproductive mechanism
o Formed within cell
o Depending on species can form centrally, subterminally (near one end), or terminally (at one end)
§ Identifying trait for species
o Appropriate conditions à endospore grows AKA germination
§ Form single cell
§ Germination triggered by sugar, amino acid, or other nutrient
o Bacillus and Clostridium only medical important genre endospore forming bacteria
§ Clostridium forms potent exotoxins and cause
· Tetanus
· Botulism
· Gas gangrene
§ Bacillus
· Anthrax
· Food poisoning
§ Widely distributed in nature
· Common in soil, plants, decaying vegetation, and intestines
§ Common contaminants of wounds
· Germinate in wounds and cause gas gangrene, tetanus, and anthrax
§ Common contaminants of vegetables and meat
· Germinate in fresh and canned foods and cause food spoilage and gastroenteritis or botulism
o Killing of endospore contaminants major concern to food industry, health care professionals, and government regulators
§ Medical and food prep operations must use sterilization processes known to kill endospores
§ States require monitoring of sterilization method effectiveness
§ PA Dept of Environmental Resources require biweekly testing of sterilization devices for med and dental instruments with biological indicator
§ OSHA, CDC, and ADA all recommend weekly testing with biological indicator
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|
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Term
|
Definition
Eukaryotic external structure
Eukaryotes without a cell well produce protective glycocalyx – glycoproteins covering plasma membrane
§ Animal and protozoan cells produce glycocalyx
§ Fungi, algae, and plant cells have cell walls and not glycocalyx
§ Functions
· Protect from outside environment
· Hold cells together
· Strengthen surface
· Protect against dehydration, microbes, injury
· Participate in cell-cell communication and recognition
§ Glycocalyx of protozoa is called pellicle |
|
|
Term
|
Definition
§ Fungi, algae, plant cells have cell walls, animal and protozoan cells don’t
§ Composed of polysaccharides, not peptidoglycan
· Plants – cellulose
· Fungi – mostly chitin, some cellulose
· Yeasts – glucans and mannans
· Algae - -cellulose and other polymers depending on species (agar, carrageenan, silicates, algin, calcium carbonate)
|
|
|
Term
|
Definition
Eukaryotic external structure
§ Structurally different than prokaryotic flagella
· Eukaryotes - Long cytoplasmic projections composed of microtubules and covered by cell membrane
· Prokaryotes – long extracellular filaments
§ Microtubules
· 9 + 2 – 9 doublets around 2 single
· Basal body – 9 + 0 (centriole)
§ Single or multiple, often at end of cell
§ Movement
· Eukaryotes – wave or whip-like motion pulls or pushes it forward
· Prokaryotes – rotate |
|
|
Term
|
Definition
§ Hairlike structures shorter than flagella
§ Could be hundreds
§ Cell-membrane bound cytoplasmic projections
§ 9+2 over 9+0 basal body
§ Whip like motion and beat rhythmically
§ Propels cell or moves nutrients |
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Term
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Definition
o Phospholipid bilayer containing
§ Sterols – more rigid at higher temps and more fluid at lower by preventing packing
§ Glycoproteins
· Recognition molecules
· Enzymes
· Receptors
· Signaling molecules
· Channels
· Transporters
· Anchors
o Prokaryotes
§ Lack sterols (except mycoplasma)
§ Have proteins not glycoproteins
o Permeability barrier
o Nutrient transport
§ Same passive and active transport as prokaryotes
§ Endocytosis
· Phagocytosis
· Pinocytosis
· Receptor-mediated endocytosis
· Exocytosis
§ Prokaryotes don’t carry out endo/exocytosis
o Phagocytosis
§ Ingestion of particulate materials by cell
§ Pseudopods extend around object, fuse together, form phagosome
§ Lysozome fuses with and forms phagolysosome
o Endocytosis
§ Pinocytosis – ingestion of liquid materials by cell
· Pseudopods extend and capture liquid in vesicle
§ Receptor-mediated endocytosis – pinocytosis involving receptor bound molecules
· Same process – receptors inside vesicle
o Exocytosis
§ Reversal of endocytosis |
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Term
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Definition
o Everything inside plasma membrane not in nucleus
o More complex than prokaryotic
§ Water
§ Inorganic and organic molecules
§ Non-membranous organelles
§ Membrane-bound organelles
§ Complex cytoskeleton
o Cytoplasm streaming – movement not found in prokaryotes |
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Term
Eukaryotic Non-Membranous Organelles |
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Definition
o Ribosomes
§ 80S – 60S and 40S
§ Larger than 70S prokaryotic
§ Many antibiotics specific for prokaryotic ribosomes
§ Can attach to ER and sends products into ER to be packaged
o Centrioles and centrosome
§ Animal and fungal cells have two microtubule structures – centrioles
· Right angles
· Form centrosome
· Participate in mitosis and cytokinesis in animal cells
· 9+0 arrangement
o Proteosomes
§ Degrade senescent, improperly folded, damaged, and or foreign proteins into peptides
· Exposed cysteines in proteins bind to sulfhydryl protein ubiquitin
· Ubiquitin-tagged proteins transported to proteosomes
§ Form epitopes bound to MHC on cell surface and presented to T cells for immune response |
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Term
Eukaryotic Vesicles and Vacuoles
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Definition
o Small – vesicles, used for transport
o Large – vacuoles, used for storage
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Term
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Definition
o Vesicles with hydrolytic enzymes
o Digest endocytosed food, microbes, etc
o Inactive at neutral pH but active at pH 5 or lower
o Proton pumps in membrane lower pH of phagolysosomes |
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Term
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Definition
o Membrane bound organelles with enzymes to decompose poisonous metabolic wastes
o Rich in catalase – destroys H2O2
o Rich in Peroxidases – destroy superoxide anion O2-, free radicals, and degrade fatty acids
o Numerous in kidney and liver cells |
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Term
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Definition
o Double membrane structures that carry out Krebs and oxidative phosphorylation
§ Inner membrane folded into cristae
§ Cristae contain ETC and are where oxidative phosphorylation happens
o Contain
§ Circular DNA
§ 70 S ribosomes
§ Replicate themselves |
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Term
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Definition
o Double membrane structures in photosynthetic cells (algae and plants) that convert light into ATP and CO2 into sugars
§ Light harvesting chemicals are pigments in membranous sacs thylakoids
§ Fluid between thylakoids and inner membrane called Stroma
§ Prokaryotes that have light harvesting pigments and photosynthetic enzymes have them in
· Folds of plasma membrane called photosynthetic lamellae
§ Circular DNA
§ 70 S ribosomes
§ Self replicating |
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Term
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Definition
o Mitochondria from small aerobic bacteria ingested
§ Became internal parasite à symbiotic relationship
§ Retained portion of DNA but lost ability to exist independently
§ Eukaryotic cell also dependent
o Similar theory for chloroplasts
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Term
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Definition
Small circular extra chromosomal DNA in prokayotes.
Convey antibiotic resistance or virulence factors and spread antibiotic resistense gens to microbes the lack them.
readily transfered form one prokaryote to another. |
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Term
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Definition
protein organelles in cytoplasm of animal cells that degrade senscent, improperly folded, damaged and/or foreign proteins in cytoplasm. ubiquitin, a small sulhydryl protein in cytoplasm, which proteosomes with exposed cysteine residues bind to exposed sulhydrl group.
Play key role in adaptive iummune response by produceing foreign (non self) peptides |
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