Glossary of Micro Chapter 1
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- Gram-positive organisms absorb ____a____ and therefore appear to be colored ___b___.
Gram-negative organisms appear ___c___ because of the counter-stain __d___.
- a. crystal-violet
- Both gram-positive and gram-negative organisms have an extra cytoplasmic layer called the cell wall, or _______a______.
The amino-acid chains of the peptidoglycan covalently bind to other amino acids from neighboring chains, with the help of a
- a. peptidoglycan
- How does penicillin work?
- It binds to and inhibits the transpeptidase enzyme (also called "penicillin binding protein") that catalyzes the formation of cell wall linkages.
- What polysaccharide present in the gram-positive cell wall acts as an antigenic determinant and is thus important for serologic identification of many gram-positive species?
- Teichoic acid
- Do bacterial cytoplasmic membranes contain cholesterol or other sterols?
- Gram-negative bacteria have a ___a____ space between the cytoplasmic membrane and the peptidoglycan layer, which is very __b___.
What is the space filled with?
- a. periplasmic
c. gel with proteins and enzymes
- Does the thin peptidoglycan layer of gram-negative bacteria contain techoic acid?
- What is the important lipoprotein present in gram-negative peptidoglycan layers? Why is it important?
- Murein lipoprotein. It is important because it extends outward to bind the unique third outer membrane.
- What is unique about the outer third membrane of gram-negative bacteria?
- It contains lipopolysaccharide.
- What carbohydrate chains are antigenic determinants in gram (-)?
Where are they found?
- O-specific side chains, O-antigen
Found in the outermost layer of LPS
- What is the center of LPS composed of?
What makes up the interior layer of LPS? What is another name for this substance?
- 1. water soluble core polysaccharide
2. Lipid A, aka gram (-) ENDOTOXIN
- Name 3 possible sequelae of gram (-) bacterial lysis in the human
- fever, diarrhea, and possible fatal endotoxic shock (septic shock)
- What class of gram organisms are vulnerable to lysozyme and penicillin attack?
- Gram (+) are vulnerable, because their thickly meshed peptidoglycan layer does not block diffusion of low molecular weight compounds.
- What are the four major bacterial shapes? Name one example of each.
- 1. Cocci: strep, staph, neisseria (diplococci)
2. Bacilli/rods: listeria, e.coli (and most gram neg)
3. Spiral forms: treponema
4. Pleomorphic: chlamydia, rickettsiae
- What are the 6 classic gram (+) bugs?
- 1. streptococcus (strips of cocci)
2. staphylococcus (clusters of cocci)
3. bacillus (bacillus with spores)
4. clostridium (bacillus with spores)
5. corynebacterium (bacillus without spores)
6. listeria (bacillus without spores)
- what is unique about LISTERIA as a gram (+) organism?
- Listeria is gram (+) but HAS endotoxin!
- What is the only group of gram (-) cocci?
- Neisseria (kissing coffeebeans diplococci)
- What is the best way to stain mycobacteria?
Name two diseases caused by mycobacteria
- acid-fast stain.
tuberculosis and leprosy.
- what is the best way to visualize spirochetes?
what STD is caused by a spirochete?
- darkfield microscopy. spirochetes are tiny gram (-) bacteria that are too small to be seen with the light microscope.
syphilis, caused by Treponema pallidum
- what group of bacteria are neither gram (+) nor gram (-)? why?
- Mycoplasma don't have a cell wall to hold on to any dye.
- Where can you usually find antibiotic resistant genes in bacteria?
- In PLASMIDS, smaller adjacent circles of double-stranded DNA.
- How do erythromycin and tetracycline act like magic bullets?
- They INHIBIT PROTEIN SYNTHESIS preferentially at the bacterial RIBOSOMAL subunits while leaving the animal ribosomes alone.
This is possible beacuse procaryotes have smaller, different ribosomes than eucaryotes.
- What 3 enzymes can bacteria possess to break down reactive oxygen products?
- 1. CATALASE: breaks down H2O2
2. PERODIDASE: breaks down H2O2
3. SUPEROXIDE DISMUTASE: breaks down superoxide radical
- What enzymes do OBLIGATE AEROBES possess to help defend themselves?
Name 3 obligate aerobes
- They have catalase, peroxidase, and superoxide dismutase.
NOCARDIA and bacillus cereus (gram pos)
NEISSERIA, pseudomonas, bordetella, legionella, brucella (gram neg)
- What two enzymes do FACULTATIVE ANAEROBES possess? Name 3 facultative anaerobes
- Catalase and Superoxide dismutase.
They are aerobic, but have the capacity to be anaerobic.
1. STAPH, Bacillus anthracis, corynebacteria, listeria, actinomyces (gram pos)
2. MOST Gram negative RODS
- What enzyme allows microaerophilic bacteria to tolerate low amounts of oxygen?
Name 3 aerotolerant anaerobes
- SUPEROXIDE DISMUTASE (no catalase like facultative anaerobes)
2. SPIROCHETES (treponema, borrelia, letpospira)
3. CAMPYLOBACTER (gram neg)
- Name two obligate anaerobes
- CLOSTRIDIUM, BACTEROIDES
- What are chemoheterotrophs and why are they important?
- All the medically important bacteria are CHEMOHETEROTROPHS, meaning they use chemical and organic compounds (like glucose) for energy.
- What is the most common fermentation pathway for the breakdown of glucose to pyruvate?
Why do we care about this in micro?
- EMBDEN-MEYERHOF pathway.
Following fermentation the pyruvate must broken down, and the different end products formed in this process can be used to classify bacteria.
- Why must obligate intracellular organisms always live in their host cell?
- Because they lack the metabolic machinery to utilize oxygen for ATP synthesis and must therefore steal their host's ATP.
Examples: CHLAMYDIA and RICKETTSIA (pleomorphic gram - )
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