Download microbio 1-3 [4-20

Chapters 1-3
Learning Objectives
Establishment of Disease
1. How is the protozoal infection Chagas disease transmitted?
 Insect bites transmit Chagas disease
2.
Some neutral bacteria crowd out pathogenic bacteria or raise useful cross-protective antibodies
Normal Microbial Flora
3. How does a loss of fibronectin in individuals in poor health change the microbial ecosystem?
 Fibronectin is used by gram-positive organisms to adhere. When it is lost, the gram-negatives
take over. Example: gram-negative pneumonia in hospital patients
4.
Why do we have antibodies to foreign blood, even if we’ve never been exposed?
 The answer is that some bacteria contain antigens that cross-react with A & B blood antigens
5.

What oranism causes diarrhea after antibiotics wipe out the normal flora?
Clostridium difficile can cause pseudomembranous colitis in people treated with widespectrum GI antibiotics
Biology of Infectious Agents
6. What are the two subunits of bacterial ribosomes called?
 Bacteria have 30S and 50S subunits (which forms the 70S ribosome)
7.
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What are the three components of Lipopolysaccharide in the gram-negative cell wall?
O Antigen
anti-hydrophobic
Core
sugar (heptose)
Lipid A
anchor & anti-hydrophilic

What kinds of substances do porins let pass?
Porins in the gram-negative cell wall let small hydrophilic compounds pass (AAs, glucose, etc.)
8.
9.
How do vancomycin and penicillins vary in their mode of action on the forming cell wall?
 Vancomycin prevents linkage of disaccharides to murein, whereas penicillin prevents the final
cross-linking of monomers: transpeptidation
10. What does group translocation do?
 Group translocation is also called phosphorylation-linked transport. The important part is
that your transport target is chemically altered.
11. What do you call a bacterial iron chelating compound?
 Each bacteria creates its own brand(s) of siderophore
12. Which is the only antibiotic that inhibits bacterial DNA replication without killing people?
 Metronidazole is selectively activated inside bacteria
[metrosexuole]
13. What determines the speed of synthesis of protein in bacteria? What antibiotic relates?
 Initiation (dependent on # of RNA polymerase molecules) is the key factor in bacterial rate of
protein production
 That’s why rifampin is useful as an inhibitor of initiation
14. Why are the drugs chloramphenicol and macrolides (erythromycin) bacteriostatic?
 These drugs block the formation of peptide bonds within ribosomes
15. Which way do flagella spin to propel a bacterium?
 When flagella all spin counterclockwise, the bacteria swims [think: 3, 2, 1, go!]
16. What do you call rapid alternation between expression and nonexpression of the flagella gene?
 Phase variation is rapid alternation of gene expression
[star trek mumbo-jumbo]
17. What’s the difference between total count and colony count?
 Colony count tells you the number of living bacteria, whereas total count includes deaders
18. What prompts the SOS response in E. Coli?
 Damage to DNA activates a set of genes responsible for repairs in the SOS response
19. Tetanus and gas gangrene are similar in that the bacteria that produce them undergo ___?___
 Sporulation occurs when the mother cell lyses, releasing crazy amounts of toxins and spores
20. What protein causes transcription to cease when its product is no longer needed? What RNA
sequences have a similar purpose in the regulation of biosynthetic enzymes?
 The repressor is a protein that stops transcription of an unecessary gene by binding to the
operator of the operon
[the scribe represses the people, denying their protein]
 Attenuators are mRNA sequences that terminate transcription of a gene when a certain AA is
abundant (example: leucine terminates transcription of enzymes that make leucine)
[mRNA AA Attenuator]