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56 Cards in this Set
- Front
- Back
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What are the 3 microbiological groups that organisms fall into? Rank them by size.
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1) Eukaryotes (protozoa, fungi)
2) Prokaryotes (bacteria) 3) Viruses Eukaryotes > prokaryotes > viruses |
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What is the smallest unit of life?
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The cell.
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What are the two measurement systems (ie millimiters, etc) used for bacteria?
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nm, um
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What are viruses? What kind of metabolism do they have? Are they smaller or bigger than bacteria?
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Obligate parasites, no intrinsic metabolism. Smaller than bacteria.
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Compare and contrast prokaryotes and eukaryotes.
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Prokaryotes:
1. no nucleus 2. no membrane bound organelles 3. haploid (single circular chromosome of double stranded DNA) 4. cell wall has peptidoglycan 5. size is less than several micrometers 6. 70s ribosomes Eukaryotes: 1. Have a nucleus 2. Have membrane bound organelles 3. Most are diploid 4. No peptidoglycan, even if cell wall is present 5. May be many times larger than bacteria 6. 80s ribosomes |
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What are organelles?
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Membrane enclosed things w/ specialized functions
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Where is the prokaryotic cell wall located with respect to the plasma membrane, and what is its function?
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External to the plasma membrane, and maintains shape even in the face of osmotic imbalance.
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What is the site of cellular respiration on a prokaryote? What is the site of cellular respiration in a eukaryote?
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Cell membrane in prokaryote, mitochondria in eukaryote
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What are the two types of microscopy and how are they different?
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1) scanning electron microscopy - gives an overview of the full structure, just scanning it briefly
2) transmission electron microscopy - gives you a cross section so you can see inside the organism, higher resolution and lets you see subcellular features |
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What is the nucleoid region in prokaryotes? Is it membrane enclosed?
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Region in prokaryotes that contains the single circular dsDNA. Not membrane enclosed - nothing in prokaryotes is membrane enclosed.
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What kind of stain can be used to identify DNA in prokaryotes?
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Feulgen stain
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Where does transcription take place in a prokaryote?
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In the protoplasm.
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What are ribosomes composed of? What are they responsible for? What kind of ribosomes do prokaryotes have? Eukaryotes?
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Ribosomes = RNA and protein. Responsible for protein synthesis. Prokaryotes have 70S (30S and 50S) Eukaryotes have 80S (40S, 60S)
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Are ribosomes organelles?
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No.
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What do inclusion bodies usually store? Where are inclusion bodies found?
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Metabolites (lipids, polysaccharides), ions. Found in the cytoplasm.
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How is the prokaryotic plasma membrane the same, and different from the eukaryotic plasma membrane?
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Same - has a phospholipid bilayer
Different - phospholipid bilayer lacks sterols. Plasma membrane in prokaryotes have the ETC (opposed to mitochondria in eukaryotes), |
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What kind of transport goes on along a prokaryotic plasma membrane?
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1. Active transport (nutrients)
2. Passive diffusion (ions) 3. Secretion (toxins, enzymes) |
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Which type of bacteria colonize teeth first?
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Gram +, because they have thicker cell walls and are sturdier. They make a biofilm that then allows gram - to adhere.
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What is peptidoglycan also known as? What is it made out of?
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Murein, mucopeptide
Made out of NAG (N-acetylglucosamine) and NAM (N-acetylmuramic acid) |
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What are the basic structural units of peptidoglycan?
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NAG and NAM, amino-acid containing carbohydrates joined by cross bridges of amino acids.
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Are NAG and NAM found in eukaryotes?
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No.
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Describe the structure of peptidoglycan. What is it permeable to? How many layers thick is it in gram +?
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Alternating NAG and NAM, multilayered, rigid. Permeable to low molecular weight ions. 40 layers thick in gram +.
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How does peptidoglycans let things in the cell wall?
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Already permeable to low molecular weight ions, have ion channels, transporter molecules, carrier molecules, and transmembrane proteins.
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What contains lysozymes? What is a major producer of lysozymes? What type of immunity do lysozymes belong to? What is its important function?
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Anything wet and lined with mucus. Major producers - major/minor salivary glands, tears.
Belong to innate immunity. Main function: hydrolyze b1-4 bond between NAG and NAM, breaking down bacterial cell wall. It's ANTIBACTERIAL. |
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What kind of microscopy is usually used to view bacteria? What do we have to do to view it?
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Light microscopy. Stain it with Gram stain.
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What kind of stains are used for which bacteria? How do they work?
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Gram stain binds to peptidoglycan in cell wall, stains gram + purple and it stays purple permanently.
Decolorize and stain gram - with safranin, which stains the outer cell wall on gram -. |
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What are mycoplasmas?
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Bacteria that have no peptidoglycan.
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Contrast gram + and gram - bacteria cell walls.
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Gram + cell wall has thick layer of peptidoglycan (40 layers, 60-90% peptidoglycan), contains teichoic and lipoteichoic acids.
Gram - cell wall has 1+ layers of peptidoglycan, has a periplasmic space that stores enzymes for antibacterial resistance, HAS AN OUTER WALL, outer wall contains LPS, no techoic acids. |
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Which bacteria is a periplasmic space found and what does it contain?
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Found in gram - bacteria and contains things that can help fight off antibiotics.
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Why is gram negative bacteria less susceptible to penicillin?
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Less peptidoglycan, periplasmic space contains defenses like beta lactamase
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What kind of antibacterial enzyme is contained in the periplasmic space? How does it funtion?
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Beta lactamase, which breaks to the beta lactam ring of penicillin, so it can't stick to the transpeptidase that promotes NAG NAM assembly.
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How does penicillin function as an antibiotic?
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It uses its beta lactam ring to stick to and interfere with transpeptidase, which is used to promote NAG NAM assembly.
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What are the 3 structural sections of LPS?
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O-antigen, core, lipid A.
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Describe the O-antigen.
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Structural section of LPS in gram - bacteria, antigenic, identifies strains of species, variable, polysaccharide, has species-specific repeat units. Elicits different types of immune responses.
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Describe the core of LPS.
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It's the same for all bacteria that are within the same species.
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Describe lipid A in LPS.
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Is responsible for the endotoxin activity of LPS. Is a glycophospholipid.
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What is the name for bacteria that is neither gram + or gram -? Example?
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Acid fast. Resists gram stains.
Mycobacterium tuberculosis. |
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The capsule - where is it located? What is it? What is it made out of?
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Located outside of the cell wall. Amorphous gelatinous layer. Made out of polysaccharides and sometimes protein.
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What is the function of the capsule?
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- It hides peptidoglycan and the cell wall, hinders phagocytosis, making it a virulence factor
Helps with bacterial adhesion |
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What kind of stain do you use to identify capsules on bacteria? How does stained capsulated bacteria look?
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India ink - capsulated bacteria shows a halo.
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What is the glycocalyx? What kind of bacteria have it?
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Polysaccharide coating on outer bacterial surfaces, allows adhesion to oral mucosa, teeth. Usually on rods or cocci.
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What are flagella used for in bacteria?
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Motility, chemotaxis.
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Describe the four arrangements of flagella.
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Monotrichous - one flagella.
Lophotrichous - tuft of flagella on one side. Amphitrichous - flagella on both sides Peritrichous - flagella all over the place |
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0157:H7 E:coli - explain the O and H
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O = somatic antigen - directly attached to bacterium
H = H antigen - flagellar antigen |
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How does flagella aid with bacterial identification?
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Using the H antigen
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What are fimbriae and pil and what do they do? Where are they found? What kind of bacteria are they predominant in?
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They're shorter than flagella and used for adhesion, can bind to surface proteins in epithelial cells on humans. Predominant in gram -. External structures.
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What does type II pili do? How does it differ from type I?
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Sex pili, used for conjugation, transfers plasmids, sometimes plasmids for resistance (beta lactamase)
Type II pili is longer |
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What does a gram stain tell us about bacteria?
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Morphology and arrangement
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Name for bacteria in:
1) clusters 2) chains 3) paired |
1) staph-
2) strept- 3) diplo- |
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What are some ways to group bacteria?
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Structure, morphology, arrangement, metabolism,
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What does the gram + bacteria have that gram - doesn't?
What does gram - have that gram + doesn't? Which type sporulates? Which is resistant to lysozymes? |
Techoic acid,
Outer membrane, LPS, periplasmic space, endotoxin. Gram - is resistant to lysozymes. Gram + sporulates. |
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If you see an O antigen, what kind of bacteria is it?
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Gram -
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Which type of bacteria have a glycocalyx?
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Rods, cocci
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Which bacteria invades gums and causes periodontal disease and gingivitis?
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P. gingivalis.
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Which two strains of bacteria cause dental caries?
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S. mutans, Lactobacillus
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What cells bind LPS and what happens as a result?
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Macrophages and neutrophils, induces fever, shock because of the endotoxin (lipid A).
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