Micr33 – Microbiology Answers – Flashcards
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| Prokaryote |
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| Comes from the Greek words for prenucleus |
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| Eukaryote |
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| Comes from the Greek words for true nucleus. |
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| Prokaryote |
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| One circular chromosome, not surrounded by a nuclear membrane, no histones, no membrane bound organelles, bacteria: peptidoglycan cell walls, archaea: pseudomurein cell walls, binary fission |
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| Eukaryote |
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| Paired chromosomes surrounded by a nuclear membrane, histones, membrane bound organelles, polysaccharide cell walls, mitotic spindle. |
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| Prokaryotic cell shape |
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| Average size: 0.2-1.0 microns x 2-8 microns Monomorphic Few are pleomorphic |
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| Glycocalyx |
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| Outside cell wall Usually sticky Capsule: neatly organized Slime layer: unorganized |
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| Flagella |
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| -outside cell wall -made of chains of flagellin -attached to a protein hook -anchored to the wall an membrane by the basal body |
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| Motile cells |
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| Rotate flagella to run or tumble Move toward or away from stimuli Flagella proteins are H antigens |
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| Axial filaments |
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| Also called endoflagella, in spirochetes, anchored at one end of cell, rotation causes cell to move. |
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| Fimbriae |
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| Fimbriae allow attachment |
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| Pili |
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| Pili facilitate transfer of DNA from one end of cell to another, gliding motility, twitching motility |
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| Peptidoglycan |
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| Polymer of disaccharide N-acetylglucosamine (NAG) N-acetylmuramic acid (NAM) |
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| Peptidoglycan in Gram-Positive Bacteria |
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| Linked by polypeptides at NAM |
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| Gram-Positive Cell Wall |
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| Thick peptidoglycan Teichoic acids: - lipoteichoic acid links to plasma membrane -wall Teichoic acid links to peptidoglycan -may regulate movement of cations and provide antigenic specificity Polysaccharides covering the cell wall may provide antigenic specificity as well |
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| Gram-Negative Cell Wall |
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| Thin peptidoglycan, outer membrane, periplasmic space |
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| Gram-Negative outer membrane |
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| Lipopolysaccharides, lipoproteins, phospholipids Forms the periplasm between the outer membrane and the plasma membrane. Protection from phagocytes, complement, and antibiotics |
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| Gram stain mechanism |
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| Crystal violet-iodine crystals form in cell -gram positive: alcohol dehydrates peptidoglycan, CV-I crystals do not leave -gran-negative: alcohol dissolves outer membrane and leaves holes in peptidoglycan, CV-I washed out |
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| Gram positive cell wall |
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| 2-ring basal body, disrupted by lysozyme, penicillin sensitive |
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| Gram-negative cell wall |
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| 4-ring basal body, endotoxin, tetracycline sensitive |
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| Atypical cell walls |
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| Acid-fast cell walls Waxy lipid (mycolic acid) bound to peptidoglycan Mycobacterium Nocardia |
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| Damage to cell wall |
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| Lysozyme digests disaccharide in peptidoglycan, penicillin inhibits peptide bridges in peptidoglycan |
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| Protoplast |
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| Wall-less cell with a plasma membrane intact |
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| Spheroplast |
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| Gram-negative cell with a remnant of the outer wall left plus an intact plasma membrane |
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| Protoplasts an spheroplasts are susceptible to osmotic lysis |
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| That's bad |
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| L forms |
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| Are wall-less cells that swell into irregular shapes (still live and divide) |
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| The plasma membrane |
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| Phospholipid bilayer, peripheral proteins and integral proteins, transmembrane proteins |
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| Fluid mosaic model |
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| Membrane'sas viscous as olive oil Proteins move to function Phospholipids rotate and move laterally |
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| Selective permeability |
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| Allows passage of some molecules |
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| Enzymes in plasma membrane |
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| For ATP production |
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| Chromatophore and thylakoids |
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| Photosynthetic pigments on foldings of plasma membrane |
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| Damage to plasma membrane |
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| By alcohols, quaternary Ammonium, polymyxin antibiotics cause leakage of cell contents |
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| Simple diffusion |
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| Movement of a solute from high to low concentration |
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| Facilitated diffusion |
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| Solute combines with a transporter protein in the membrane |
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| Facilitated diffusion |
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| Solute combines with a transporter protein in the membrane |
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| Osmosis |
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| The movement of water across a selectively permeable membrane from an area of high water concentration to an area of low water concentration |
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| Osmotic pressure |
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| The pressure needed to stop the movement of water across the membrane. |
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| Aquaporin |
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| The channel through which water moves through the plasma membrane |
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| Isotonic solution |
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| Equal concentration |
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| Hypotonic |
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| Water moves into cell. Might burst. |
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| Osmotic lysis |
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| Cell bursts from osmosis |
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| Hypertonic solution |
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| Water moves out of the cell causing cytoplasm to shrink |
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| Plasmolysis |
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| Cell shrinks |
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| Active transport |
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| Requires a transporter protein and energy in the form of ATP |
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| Group translocation |
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| Requires a transporter protein and PEP (a special form of active transport in prokaryotes. Substances are altered as they are transported. |
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| Cytoplasm |
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| The substance inside the plasma membrane (not a void, it is a very rich environment) |
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| The nucleoid |
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| Bacterial chromosome. No boundary to mark nucleoid location |
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| PEP |
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| Phosphoenol pyruvate |
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| The prokaryotic ribosome |
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| Protein synthesis. Complete 70S structure. Made of 1 small subunit (30S) and one large unit(50S). S stands for Svedberg unit. Ribosome is non membranous. It is made of protein and RNAs |
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| Meta chromatic granules (volutin) |
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| Phosphate reserves, for generating ATP |
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| Polysaccharide granules |
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| Energy reserves |
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| Lipid inclusions and sulfur granules |
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| Energy reserves |
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| Carboxysomes |
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| Ribulose 1,5-diphosphate carboxylase for CO2 fixation |
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| Gas vacuoles |
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| Protein-covered cylinders Help organisms float for photosynthetic purposes |
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| Magnetosomes |
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| Iron oxide (destroys H2O2) Hydrogen peroxide is toxic, this helps rid of it. |
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| Svedberg unit |
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| "S" in ribosomes. Accounts for size, weight, and shape. A unit of sediments |
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| Endospores |
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| Resting cells. Resistant to desiccation, heat, chemicals. -Bacillus(genus) -Clostridium(genus) |
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| Sporulation |
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| Endospore formation |
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| Germination |
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| Return to vegetative state |
