10.17 Intro to Bacteriology – Flashcards
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| What type of ribosomes are in eukaryotes? |
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| 80S |
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| T/F Most bacteria possess peptidoglycan |
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| true |
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| T/F Prokaryotic mRNA is usually spliced before it can be translated. |
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| false! prokaryotic mRNA does not need processsing |
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| What are the four steps of the gram stain? |
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| step 1= crystal violet for 1 min, rinse step 2= Gram's Iodine for 1 min, rinse step 3= decolorizer (alcohol or acetone) for 30-60 seconds and rinse step 4= safranin red |
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| What color are gram positive and gram negative bacteria on a gram stain? |
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| gram + are blue, gram - are red |
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| What color do acid fast positive bacilli stain? |
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| stain red (while acid fase - bacteria stain blue) |
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| What are the steps for acid fast staining? |
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| primary stain (carbolfuchsin red) for 5 minutes then rinse, decolorizer (HCl, alcohol), and then counterstain with methylene blue or malachite green for 1-3 minutes |
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| What are capsules made out of? |
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| high MW polysaccharide or peptide like N-acetylmuramic acid (NAM) and N-Acetylglucosamine (NAG) |
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| How do capsules help bacteria evade the immune system? |
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| protect against complement and are anti-phagocytic. Also capsules facilitate adherence of bacteria to surfaces. |
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| How big are bacteria? |
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| most range in size .25-1 um wide and 1-3 um long |
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| In gram staining, idion acts as a ____ and complexes with crystal violet in the cytoplasm of bacteria. |
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| mordant |
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| What factors can affect the results of gram staining? |
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| old cultures of g+ may appear G variable. Antibiotic treated cells can give false gram reactions. Also cell walls with LCFA are difficult to decolorize with acetone/alcohol and appear as poorly stained gram + |
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| T/F All bacteria have cell walls. |
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| false, ex. mycoplasma doesn't |
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| What determines if a bacteria is acid fast or not? |
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| presence of LCFA (mycolic acids) in bacterial cell walls make them AF |
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| What are the two methods for acid fast staining? |
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| hot (Ziehl-Neelsen) or cold (Kinyoun) methods. Cold is more often used today |
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| What do acid fast + bacteria look like on acid fast stain? |
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| AF+ are red, AF- are blue or green |
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| round bacteria = |
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| coccus |
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| ovoid bacteria= |
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| coccobacillus |
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| rod-shaped bacteria = |
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| bacillus |
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| spindle shaped bacteria = |
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| fusiform |
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| "seagull" or comma-shaped bacteria= |
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| curved |
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| Corkscrew shaped bacteria= |
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| spiral |
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| What are the common cell arrangements of bacteria? |
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| single, pairs, tetrads, clusters, chains |
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| production of bacterial capsule depends on... |
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| environmental and growth conditions |
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| What is a glycocalyx? |
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| a less organized form of a capsule that is a polysaccharide film over the surface of bacterial cells |
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| What is an S-layer? |
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| slime layer that appears as a matrix of fibers, even less organized than the glycocalyx |
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| What is the outer membrane of a bacteria composed of? |
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| bilayer of LPS and phospholipids |
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| Which bacteria have outer membranes? why? |
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| gram negative, they function as an initial barrier to the environment |
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| What are LPS made out of? |
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| repeating sugar residues attached to core sugars which are then attached to a disaccharide-diphosphate with fatty acid moieties. Repeating sugar residues are useful for bacterial typing (Oantigen), impart a hydrophilic nature ot the bacterial cell |
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| What is the bioactive portion of LPS? |
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| lipid A= disaccharide diphosphate with fatty acid chains |
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| What are porins? |
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| proteins scattered throughout the LPS which control the passage of small water soluble nutrients and other molecules like antibiotics, and specialized transport proteins for larger hydrophobic compounds |
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| What is the purpose of the lipoproteins scattered throughout bacterial LPS? |
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| anchor the outermembrane to the next deeper layer in the cell envelop, the cell wall |
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| What's another name for the peptidoglycan layer? |
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| murein layer |
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| What is the function of the peptidoglycan layer? |
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| found in both gram + and gram - bacteria; gives bacteria cell shape and strength to resist osmotic changes in teh environment. Protects against mechanical damage and provides some barrier effect against larger substances |
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| What is the peptidoglycan layer/murein layer composed of? |
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| disaccharide-pentapeptide subunits which are N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM). Crosslinked via peptide bridges between NAM to form sheets of peptidoglycan. Sheets of peptidoglycan are then crosslinked. |
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| What's the different b/t the peptidoglycan layer of G+ and G-? |
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| in G+, the peptidoglycan layers have teichoic or mycolic acids (acid-fast) to fortify cell walls |
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| What is the periplasmic space? |
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| in G- bacteria, bounded by the internal surface of the outermembrane and the external surface of the cytoplasmic membrane. Contains thin layer of peptidoglycan. |
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| T/F The cytoplasmic membrane of bacteria generates ATP. |
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| true |
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| T/F The cell membrane mediates chromosomal seperation during bacterial replication. |
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| true |
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| What are pili composed of? |
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| subunits of protein called pilin, which are found in a pool together with assembly machinery in the periplasmic space |
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| What are the two types of pili? |
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| common and sex |
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| What is the function of common pili? |
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| fimbriae or type IV pili mediate adhesion to host eukaryotic cells with specialized tipstructures to recognize specific carbs |
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| What are sex pili? |
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| serve as conduits for passage of DNA from one bacterial cell to another ina process known as conjugation |
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| Rapid extension and retraction of type ___ ili results in a form of locomotion known as _____. |
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| IV; twitching motility |
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| T/F Pili and flagella are antigenic. |
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| true |
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| What are flagella? |
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| long helical filaments composed of a rotary motor (a basal body complex with assoc proteins), a flexible universal joine (the hook), and a rigid propeller (a filament composed of a single protein-flagellin) |
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| What is H antigen? |
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| the antigen for flagellin (highly antigenic) |
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| What is H antigen? |
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| the antigen for flagellin (highly antigenic) |
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| What powers the flagella motor? |
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| protons |
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| What is the purpose of inclusion bodies in bacteria? |
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| store reserve granules (glycogen and polyphophate are the MC) |
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| What is the nucleoid? |
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| highly coiled bacterial chromosome intermixed with RNA, polyamines, and support proteins |
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| What are two different types of plasmids? |
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| resistence and virulence |
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| What are endospores? |
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| a resting phase of bacteria when living conditions get tough, NOT A REPRODUCTIVE STRUCTURE |
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| Endospores are resistent to... |
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| desiccation, light, heat, many disinfectants, radation, etc. |
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| How do you kill spores? |
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| autoclaving, high heat for a period of time and right concentrations of certain disinfectants |
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| What are mesosomes? |
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| invaginations of the cytoplasmic membrane, involved in septation |
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| How do bacteria bring in nutrients? |
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| passive and carrier mediated diffusion, active transport, group translocation |
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| What substances do bacteria bring in to the cell via passive and carrier mediated diffusion? |
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| water, O2, carbon dioxide, and simple sugars enter by virtue of a concentration gradient |
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| What nutrients do bacteria bring in via active transport? |
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| energy dependent pumps in the cell envelope bring certain sugars, most amino acids, organic acids, and many inorganic ions into the cell |
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| What do bacteria bring into the cell via group translocation? |
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| similar to active transport but the nutrient being transported gets chemicallymodified before being brought into the cell; many sugars, purines, pyrimidines, and fatty acids are brought in this way |
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| T/F If possible, bacteria would rather use preformed compounds like amino acids, vitamines, nucleotide phosphates, etc. rather than synthesize them de novo. |
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| true |
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| What are fastidious growers? |
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| bacteria that have lost the ability to synthesize substances essential to growth and will only thrive in their hosts |
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| What two general mechanisms do bacteria use to generate ATP? |
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| substrate level phosphorylation and oxidative phosphorylation |
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| How do bacteria cause dental caries? |
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| oral S. mutans takes in sucrose and rapidly ferments it into acids which then eat into tooth enamel |
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| What does it mean for a bacteria to be microaerophilic? |
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| can only handle small amounts of oxygen otherwise it will be toxic |
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| Trimethoprim inhibits what bacterial enzyme? |
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| dihydrofolate reductase |
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| How does trimethoprim specifically inhibit bacterial dihydrofolate reductase and spare human DHFR? |
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| human enzyme needs 50,000 x bacterial dose for inhibition |
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| Peptidoglycan is synthesized from monomeric units composed of ____ coupled to either NAG or NAMA. |
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| uridine diphosphate (UDP) |
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| UDP-NAG and UDP-NAMA are polymerized then crosslinked to each other by means of a __ reaction. |
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| transpeptidation reaction |
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| What's a really complicated name for the glycolytic or anaerobic pathway? |
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| EMP (Emden-Myerhof-Parnas) |
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| What are the end products of fermentative metabolism? |
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| acids, alcohols, carbon dioxide, and hydrogen |
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| What are different ways to distinguish between different bacteria? |
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| staining, selective media, differential media, sequence 16S ribosomal RNA |
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| What are some examples of bacterial aerobes? |
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| mycobacterium tuberculosis, pseudomonas aeruginosa, and bacillus anthracis |
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| What are some examples of anaerobe bacteria? |
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| clostridium botulinum, bacteriodes melaningenicus |
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| What are some examples of bacterial facultative aerobes? |
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| E coli, shigella dysenteriae, s. aureus |
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| What is an example of a bacterial microaerophilic? |
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| campylobacter jejuni |
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| Who created the first antibiotic and what was it? |
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| prontosil rubrum (prodrug of sulphanilamide) by Gerhard Domagk |
