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48 Cards in this Set

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  • Back
All living things require a source of elements, such as C, H,O, P, K, N, S, Ca, Fe, Na, Cl, Mg, and certain other elements. TRUE/FALSE
What is an essential nutrient?
Any substance, whether in elemental or molecular form, that must be provided to an organism.
List some elements required for E. coli.
A cell as simple as E. coli contains on the order of 5,000 different compounds, yet needs to absorb only a few types of nutrients to synthesize this great diversity. these include NH4SO4, FeCl2, NaCl, trace elements, glucose, KH2PO4, MgSO4, CaHPO4 and water.
Is Thiobacillus considered an extremophile?
Yes. They not only require such a low pH for growth, but particular bacteria(for example, Thiobacillus) actually help maintain the low pH by releasing strong acid.`
What is an heterotroph?
It is an organism that must obtain its carbon in an organic form.
What is an autotroph?
Is an organism that uses inorganic CO2 as its carbon source. They convert CO2 into organic compounds. (not nutritionally dependent on other living things)
The main reservoir of N is nitrogen gas(N2), which makes up 79% of the earths atmosphere. TRUE/FALSE
TRUE. These nitrogenous compounds are the primary N source for heterotrophs.
regardless of the initial form in which the inorganic nitrogen enters the cell, it must first be converted to NH3, the only form that can be directly comnbined with carbon to synthesize amino acids and other compounds. TRUE/FALSE
Free gaseous O2 makes up app 20% of the atmosphere. TRUE/FALSE
What type of bacterium is able to concentrate and store phosphate in metachromatic granules.
What are zinc fingers?
Zinc is an essential regulatory element for eucaryotic genetics. It is a major component of zinc fingers, binding factors that help enzymes adhere to specific sites on DNA.
Metal ions are also toxic to microbes in high concentrations. TRUE/FALSE
TRUE. In general this appears to be the case. Yet, the bacteria that cause gonorrhea and meningitis grow more rapidly in the presence of iron ions.
What is a growth factor?
An organic compound such as an amino acid, nitrogenous base or vitamin that cannot be synthesized by an organism and must be provided as a nutrient.
Does haemophilus influenzae have a specific nutritional rerquirement?
This bacterium that causes meningitis and respiratory infections in humans, can grow only when hemin(factor X), NAD(factor V), thiamine and pantothenic acid(vitamins), uracil and cysteine are provided by another organism or a growth medium.
Autotrophs derive energy from one of two possible non-living sources. What are they?
1. Photoautotrophs
2. Chemoautotrophs
What is a photoautotroph?
They are photosynthetic, they capture the energy of light rays and transform it into chemical energy that can be used in cell metabolism.
What are chemoautotrophs?
They are of 2 types.
Chemoorganic autotrophs- They use organic compounds for energy and inorganic compounds as a carbon source.
2. Lithoautotrophs- requires neither sunlight nor organic nutrients, relying totally, on inorganic minerals.
The majority of heterotrophic microorganisms are chemoheterotrophs that derive both carbon and energy from organic compounds. TRUE/FALSE
TRUE. (aerobic respiration)
What are saprobes?
They are free living microorganisms that feed primarily on organic detritus from dead organisms.
Obligate saprobes exist strictly on dead organic matter in soil and water.
What is an opportunistic pathogen?
Although its natural habitat is soil and water, Pseudomonas aeruginosa, frequently causes infections in hospitalized patients.
Cryptococcus neoformans causes a severe lung infection in AIDS patients.
Rickettsias are primarily energy parasites, and the malaria protozoan is a hemoglobin parasite. TRUE/FALSE
Under hypotonic conditions, the solute concentration of the external environment is lower than that of the cells internal environment. TRUE/FALSE
TRUE. Pure water provides the most hypotonic environment for cells because it has no solute.
The amoeba has a water or contractile, vacuole that siphons excess water back out into the habitat like a tiny pump. TRUE/FALSE
TRUE. As well, Halobacteria living in the great salt lake and the dead sea actually absorb salt to make their cells isotonic with the environment.
What is Diffusion?
It is the net movement of molecules down their concentration gradient by random thermal motion.
What is receptor specificity?
These carrier proteins which exhibit this, they bind and transport only a single type of molecule. A carrier protein that transports sodium will not bind glucose.
What is group translocation?
This is considered active transport. It couples the transport of a nutrient with its conversion to a substance that is immediately useful inside the cell. Used by bacteria, while simultaneously adding molecules such as PO4 that prepare them for the next stage in metabolism.
The typhus Rickettsia multiplies only in the range of 32C to 38C, and rhinoviruses(common cold), multiply sucessfully only in tissues that are slightly below normal body temperture(33-35C. TRUE/FALSE
TRUE. Starins of Staph. aureus grow within the range og 6C to 46C, and the intestinal bacterium Enterococcus faecalis grows within the the range of 0C to 44C.
What is the difference between a true psychrophiles and psychrotrophs?
True psychrophiles must be distinguished from psychrotrophs or facultative psychrophiles that grow slowly in cold but have an optimum temperature above 20C.
Staph. aureus and Listeria monocytogenes are of concern because they can grow in refrigerated food and cause foo-borne illness. TRUE/FALSE
What is taq polymerase?
From this, researchers were able to develop a technique called polymerase chain reaction(PCR) which could amplify a single piece of DNA into hundreds of thousands of identical copies. It was from Therus acquaficus.
The majority of medically relevant microorganisms are mesophiles that grow at intermediate temperatures(20-40C) TRUE/FALSE
What is a Thermoduric microbe?
They are microbes that can survive short exposure to high temperatures, but are normally mesophiles, and are common contaminates of heated or pasteurized foods.
What is a thermophile?
It is a microbe that grows optimally at temperatures greater than 45C.
What is singlet O2?
As o2 enters into cellular reactions, it is transformed into several toxic products. It is an extremely reactive molecule produced by both living and non living processes. It is produced by phagocytes to kill invading bacteria.
List several other destructive molecules that can damage and destroy a cell?
1. Superoxide ion(O2)
2. peroxide (H2O2)
3. Hydroxyl radicals(OH-).
What is superoxide dismutase?
In a series of reactions(essential for aerobic organisms), the superoxide ion is first converted to H2O2 and normal O2 by the action of an enzyme, superoxide dismutase.
What is a microaerophile?
This agent does not grow at normal atmospheric concentrations of O2 but requires a small amount of it in metabolism
What are aerotolerant anaerobes?
These do not utilize O2, but can survive and grow to a limited extent in its presence. They are not harmed by O2. They possess certain mechanisms for breaking down peroxides and superoxide.
certain lactobacilli and Streptococci use manganese ions or peroxidases to perform this task.
What are capnophiles?
Although all microbes require some CO2 in their metabolism, capnophiles grow best at a higher CO2 tension that is normally present in the atmosphere. This is important in the initial isolation of some pathogens from clinical specimens, notably, neisseria(gonorhhea, meningitis), Brucella and Streptococcus pneumoniae.
What is an acidophile?
Organisms that live at pH extremes.
Obligate acidophiles include Euglena mutabilis(alga),between 0-1.0, and Thermoplasma, an archaea that lacks a cell wall, lives in hot coal piles.
Bacteria that decompose urine create alkaline conditions, since NH4 can be produced when urea is digested. TRUE/FALSE
TRUE. Metabolism of urea is one way that Proteus spp can neutralize the acidity of the urine to colonize and infect the urinary system.
What are barophiles?
Deep sea microbes called barophiles exist under pressures that range from a few times to over 1,000 times the pressure of the atmosphere.
What is satellitism?
A classic commensal interaction between microorganisms arises when one member provides nutritional or protective factors needed by the other.
What is doubling time/
The time required for a complete fission cycle, from parent cell to two new daughter cells.
Average generational time for bacteria is 30-60 minutes.
What is the generation time of Mycobacterium leprae?
10-30 days.(Hansen's disease)
What are the growth curve phases in bacteria?
1. Lag phase
2. Exponential growth phase(log)
3. Staionary phase
4. Death phase
The cells reach the maximum rate of cell division, during the exponential growth phase, a period during which the curve increases geometrically, as long as there is adequate nutrients. TRUE/FALSE
What is a Chemostat/
It is an automatic growth chamber. This device can admit a steady stream of new nutrients and siphon off used media and old bacterial cells.