Help
Options
Didn't know it?
click below
click below
Knew it?
click below
click below
Don't Know
Remaining cards (0)
Know
retry
shuffle
restart
0:00
Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.
Normal Size Small Size show me how
Normal Size Small Size show me how
Microbio
Ch. 6 - Microbial Growth & Nutrition
| Question | Answer |
|---|---|
| Classify microbes into 5 groups based on preferred temperature range (low to high) | Psychrophiles (cold-loving), psychrotrophs (15-30C), mesophiles (moderate-temp of 20-40C), thermophiles (heat-loving), hyperthermophiles. |
| Bacteria grow best at what pH range? | 6.5 - 7.5 |
| Molds and yeasts grow best at what pH range? | 5 - 6 |
| What is added to culture media to control pH? | Buffers |
| Bacteria that grow in acidic environments are called _____. Bacteria that grow in salty environments are called ______. | Acidophiles; halophiles. |
| Hypertonic solutions vs hypotonic solutions on cells | Hypertonic solutions cause plasmolysis (shrinkage of the cell). Hypotonic solutions cause osmotic lysis (rupture) |
| Why is carbon important for microbial growth? | It composes all organic molecules; is the energy source. |
| Why is nitrogen, sulfur, and phosphorous important for microbial growth? | Nitrogen - protein synthesis, component of DNA/RNA. Sulfur - amino acids. Phosphorous - ATP, cell membranes. |
| Define obligate aerobes | Requires oxygen |
| Define facultative anaerobes | Grow best in oxygen, but will grow via fermentation or anaerobic respiration when oxygen is not available. |
| Define anaerobes | Unable to use oxygen; most are harmed by it |
| Define aerotolerant anaerobes | Tolerate but cannot use oxygen |
| Define microaerophiles | Require oxygen concentration lower that air; still are aerobic. |
| What toxins are produced in the ETC of aerobic respirations? (2) | Superoxide radical and hydrogen peroxide |
| Why is oxygen toxic to obligate anaerobes but not aerobic bacteria? | Aerobic bacteria contain the enzymes superoxide dismutase and catalase (aka peroxidase) that destroys the toxins produced during aerobic respiration. Obligate anaerobes do not have these enzymes. |
| Define biofilm | Multiple species of bacteria in a polysaccharide matrix (slime) |
| Define quorum sensing | Cell-to-cell communication that allows bacteria to coordinate their activity in a biofilm. |
| Define capnophiles and list 2 methods of culturing them. | Microbes that require extra CO2. Methods include a candle jar and CO2 generating packet. |
| Does the agar in an agar plate provide any nutrients? | No. Agar is the polysaccharide solidifying agent in the plate. Nutrients are supplemented. |
| What is the difference between chemically defined media and complex media? | A chemically defined medium is one whose exact chemical composition is known, whereas in a complex medium, the chemical composition varies from batch to batch. |
| What is enriched media? Give examples | Media needed to grow fastidious bacteria. Ex) TSA + sheep's blood (blood agar); TSA + heated sheep's blood (chocolate agar) |
| What is fastidious bacteria? | Bacteria that have extra nutritional requirements |
| What is selective media? Give examples | Media that suppress the growth of unwanted microbes and encourage the growth of desired ones. Ex) Martin Lewis Agar (antibiotics are added); Phenylethylene alcohol agar (inhibits gram neg bacteria) |
| What is differential media? | Chemicals are added to make it easier to distinguish one microbe from another. |
| Give examples of media that are both selective and differential, and explain how they work. (2) | Mannitol salt agar - selective because only Staph grow on this due to high salt content, differential because only Staph. aureas turn yellow when it ferments the mannitol. MacConkey Agar - selective for only gram neg, lactose fermenters will turn pink |
| What is the difference between BSL levels 1-4? I.e. what PPE is needed for each type of lab? | BSL 1 - none; no obvious risks. BSL 2 - gloves, coat, eye protection; moderate risk of infection. BSL 3 - negatively pressured room, air filters; infection airborne agents. BSL 4 - negative pressure building, spacesuits; "hot zone". |
| Define colony | Population of cells arising from a single cell or spore. |
| What are the 4 phases of the bacterial growth curve? | Lag phase, Log phase (exponential growth), Stationary phase, Death phase. |
| What are 3 direct methods of measuring cell growth? | Plate counts, filtration, direct microscopic count. *count # of cells |
| What are 2 indirect methods of measure cell growth? | Turbidity, genetic probing. *estimation of # of cells |
| Cell macronutrients | CHONPS - carbon, hydrogen, oxygen, nitrogen, phosphorous, sulfur |
Created by:
catfreak711