Exam 2 – Microbiology Terms – Flashcards
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| Psychrophiles |
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| 0-20C |
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| Mesophile |
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| 15-45C |
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| Thermophile |
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| 40-80C |
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| Hyperthermophile |
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| 80-121C |
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| Heat-shock response |
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| stabilizes proteins and membranes in response to high heat. |
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| What are the physical agents that impede bacterial growth? |
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| Pasteurization, freezing, irradiation, and autoclave. |
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| What is the D-value, and what does it test? |
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| The D-value tests the efficacy of a lethal agent, refers to the length of the time it takes for the agent to kill 90% of the population. |
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| What pH do acidophiles live in? |
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| 0-5 |
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| What do halophiles require? |
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| High sodium. |
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| Where do Barophiles live? |
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| High pressure environments |
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| Where do psychrophiles live? |
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| High pressure environments |
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| Obligate Aerobe |
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| Requires 02 |
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| Obligate Anaerobe |
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| Requires CO2 |
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| Faculative Anaerobe |
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| Can grow in O2 and CO2, prefers O2. |
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| Microarophile |
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| Needs small amounts of CO2, less than 21% |
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| Aerotolerant |
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| Uniformed growth in O2 |
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| How do aerobes functions with O2? |
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| They use peroxidases, super peroxidases, and catalases to break bad things like peroxide. |
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| Do anaerobes have peroxidases? |
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| No. |
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| What is an autoclave? |
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| Steam bath that heats bacteria for 121C for 15-20 minutes. |
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| What does heat-labile mean? |
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| Susceptible to alteration from heat. (proteins are heat-labile). |
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| What is the Phenol Coefficient test, and what is it for? |
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| It is used to compare disinfectants to phenol by exposing the target to both for 10 minutes. |
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| Facts about plasmids? |
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| 1) Confer bacterial resistance. 2) Multiple plasmids per cell. 3) The can be transmitted via horizontal gene transfer. 4) They are naked DNA. 5) They are only found in bacteria/archae. 6) They are between 2-25kb |
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| How are plasmids replicated? |
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| Rolling circle replication, which starts at a nick. |
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| What is a high copy, and low copy number for the number of plasmids in a cell? |
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| more than 50, and 1-2. |
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| What is the central dogma of biology? |
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| DNA to RNA via transcription. RNA to protein via translation. |
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| What is mRNA? |
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| Something that is translated into a protein. |
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| What is a holoenzyme? |
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| A protein (enzyme) + sigma factor (whcih is located at -10 and -35 bp upstream from the transcription storage site). |
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| What is the sigma factor for, and when does it fall off? |
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| The sigma factor is for transcription initiation. It falls off during RNA synthesis. |
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| What are the names of chaperonins? |
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| GROEL, GROES, and DNAK. |
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| What does tRNA do? |
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| Makes a molecule of RNA from DNA template. |
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| What is Rho dependent termination? |
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| It involves the Rho factor that moves along the DNA strand and ends transcription. |
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| What is Rho independent termination? |
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| Transcription that ends when a stop sequence is reached. |
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| What do prokaryotic ribosomes consist of? |
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| tRNA, RNA, and mRNA (as well as proteins). |
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| 30s, 50s, and 70s? |
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| Prokaryotic |
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| 40s, 60s, and 80s? |
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| Eukaryotic |
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| What can prokaryotes do that eukaryotes cannot (in relation to ribosomes)? |
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| They can have may ribosomes work simultaneously. |
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| Which cycles are part of the generalized transduction cycles? |
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| The lytic and lysogenic cycle. |
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| What is does specialized transduction cycle effect? |
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| Transfer of closely linked genes |
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| What is transformation? |
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| gene transfer that takes up naked DNA fro the environment. |
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| What is natural transformation and who does it? |
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| Gram positive do it, and its the natural ability to perform transformation. |
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| What is artificial transformation and who does it? |
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| Gram negative do it, and its the assisted ability to perform transformation. |
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| What does RecA do? |
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| scans DNA for homology |
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| What does RecBCD do? |
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| It unwinds DNA. |
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| What does RuvAVB do? |
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| Aids in single stranded cross-over pairing. |
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| What are sign of horizontal gene transfer? |
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| Different genomes between two different members of the species. A different G-C base ratio from flanking chromosomal DNA. |
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| How does replicative tranposition differ from nonreplicative transposition? |
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| Replicative (copy and paste) Nonreplicative (cut and paste) |
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| How is cell function regulated? |
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| Via extracellular signals and biochemical pathways. |
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| Where can an enzyme be most rapidly changes? |
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| Post translation level. |
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| What does an inducer cause? |
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| An inducer causes gene expression by binding a repressor protein (inducer starts gene expression). |
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| When is the lac operon maximally transcribed? |
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| The lac operon is maximally transcribed when lactose is present, but not glucose (because if glucose is present, then you don't need the lactose) |
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| What is a repressor? |
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| Something that turns off an operon. |
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| What is the mechanism by which the repressor controls the operon? |
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| Induction. |
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| What is catabolite repression? |
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| The the product thats usually unavailable represses the operon (glucose is the catabolite responsible for lactose operon repression). |
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| How is the tryptophan operon regulated? |
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| Its regulated by both repressor, and attenuation (down regulation). |
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| What is attenuation control? |
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| Stops transcription. |
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| What can small regulatory RNA do? |
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| Compliment base pairs with mRNA. |
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| What is phase variation? |
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| An alternative DNA sequence that can code for a bacteria's cell surface structure, such as LPS, PLE, and flagella. This processes involves DNA rearrangement. |
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| When does a stringent response occur? |
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| When energy stores are low to decrease rRNA transcription. |
