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Growth and Control
Microbiology I - Exam 2 - Growth and Control
| Question | Answer |
|---|---|
| Ways to measure growth | plating, absorbance, biological activity |
| Measuring growth by absorbance uses a measure of _____ at a certain ____ | od, wavelength |
| Measuring absorbance at wavelength of 500 nm is indicated by the following notation: | OD500 |
| Microbes will grow as long as ___, ___, and ___ are present | nutrients, temperature, water |
| "OD" means | optical density |
| Making lipid membranes takes how many Acetyl CoA? | 9 |
| How many carbons in one Acetyl CoA? | 2 |
| Growth is characterized by | synthesis of new cell components, DNA replication |
| What is the most energy intensive celllular component to grow? | lipid membrane |
| Growth curve has the following phases: | lag, log, stationary, death |
| Growth phase in which organisms are recovering from past damage, preparing to make use of available nutrients | lag |
| Growth phase in which growth of population is exponential | log |
| During log phase, synthesis of all cllular components must be | balanced |
| What can induce a lag phase? | shift in nutrients |
| What is the main characteristic of lag phase? | adjustment |
| What is the main characteristic of log phase? | exponential growth |
| Generation time: N is | number of bacteria after n generations |
| Generation time: n is | number of generations |
| Generation time: No is | initial number |
| Generation time: g is | generation (doubling) time |
| What is the equation for total number of organisms? (in words) | total number = initial number x 2 to the number of generations |
| What is the equation for the number of generations? (in words) | number of generations = time / generation time |
| Cell division when both cells have a combination of old and new parts and are the same size | binary fission |
| When cells divide by binary fission, is there a parent and daughter cell? | no |
| Cell division when new cell starts at small point on cell surface | budding |
| What kind of organism commonly divides by budding? | yeast |
| When cells divide by binary fission, is there a parent and daughter cell? | y |
| Cell division in which there is a daughter cell made of almost entirely newly synthesized parts | budding |
| Water availability is quantified as: | water activity |
| A measure of how much salt is dissolved in water, or how much water is available in a salt solution | water activity |
| Water activity can be defined as | relative humidity in a closed environment |
| Pure water has a water activity of ___ and a relative humidity of ___%. | 1.0, 100 |
| Organisms that can grow over a wide range of water activities (but mostly around .98) are called | halotolerant |
| The water activity of seawater is about | .98 |
| Organisms that prefer or are tolerant of very low water activities are called | halophiles |
| Optimal molarity for halophiles is above ___M, or above ___M to ____. | 0.2, 2, saturation |
| Two places halophiles might live | dead sea, great salt lake |
| How to halophiles and halotolerant organisms handle lower water activities? | accumulate solutes within cytoplasm - fights off osmotic pressure, often have specially adapted enzymes and membranes |
| What it the preferred pH for alkaphiles? | 8-10 |
| What is the preferred pH for extreme alkaphiles? | 10+ |
| What is the internal pH range that all organisms must maintain? | 5-10 |
| What type of damage occures at pH below 5? | protein hydrolysis |
| What type of damage occurs at pH range above 10? | base hydrolysis of RNA |
| What can be done in a lab to help organisms tolerate pH? | add buffers |
| What are two ways that organisms can tolerate pH levels? | ATPase to pump out H+, chaperones to prevent acid denaturation |
| What is the expected distribution of an organism's tolerance to temperature ranges? | bell curve |
| Growth can occur from a temperature of ____ C up to ____C. | -20, 120 |
| What condition must be present for growth to occur at tempts above 100C? | water must be under pressure to remain liquid |
| What is the one place on the surface of the earth where organisms DO NOT grow? | active volcanoes - too hot for C-C bonds! |
| Optimal temps for psychrophiles are from ___C to ___C, with maximal growth at about ___C. | 0, 20, 15 |
| An example of a psychrophile is | chlamydomonas algae - pink snow from red spores! |
| What are the organisms that cause food spoilage in the fridge? | facultative psychrophiles |
| Optimal temps for facultative psychrophiles are from ___C to ___C, with maximal growth at about ___C. | 0, 30, 25 - fridges are about 4C |
| Optimal temps for thermophiles are from ___C to ___C. | 55-65 |
| Optimal temps for hyperthermophiles are from ___C to ___C. | 90-113 |
| Three mechanisms for heat tolerance: | stable DNA, stable proteins, more fliud lipid layer |
| How do thermophiles stabilize DNA? | locked in protein rings |
| At what temp does DNA melt? (in C) | 75 |
| How do thermophiles stabilize proteins? | no loose ends, well organized interior, high proline content - proline can't rotate - is less flexible! |
| In terms of O tolerance, most bacteria are ____ or ____. | obligate anaerobes, facultative anaerobes |
| An organism that does not require O2, but prefers it: | facultative anaerobe |
| An organism that does not require O2 and does NOT prefer it: | aerotolerant |
| Many organisms that live in our bodies are ____ (in terms of O tolerance) | microaerophiles |
| Superoxidase dismutase destroys | superoxidase |
| What kind of damage can radicals do? | DNA mutation |
| What enzymes destroy H202? | catalase, peroxidase |
| Alpha radiation consists of: | helium nuclei |
| Beta radiation consists of: | electrons |
| Gamma radiation consists of: | photons |
| Which kind of radiation is bad for bacteria? | gamma |
| Can alpha and beta radiation cause mutations? | y, but usually from an artificial source |
| What do gamma and X- rays do that make them dangerous? | excite electrons so much they leave, creating radicals - can also damage DNA directly! |
| What kind of damage does UV radiation cause? | thymine dimers, tryptophan breakdown |
| What is the wavelength that causes thymine dimers in DNA? | 260nm |
| What wavelength does tryptophan absorb? | 280nm |
| How do microwaves cause damage to microbes? | heat water to letal temps |
| Do microwaves have enough energy to break bonds or ionize? | no |
| What physical barrier is used against radiation? | pigments that block UV light |
| What mechanisms are used to combat radiation damage? | DNA repair enzymes, radical degrading enzymes, multiploid genome, compact nucleoid |
| How does a compact nucleoid protect against radiation damage? | more concentrated pigments, repair enzymes, less space for falling apart |
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epiphenom
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