Biol 257: chapters 10-13
Which of the rRNA molecules has proven the most useful in taxonomy/identification?
16s
Which type of ribosomal RNA is most often used in taxonomy?
16s
To study the phylogeny of eukaryotes,
18s rrna is used
Which technique(s) is/are used to help identify and classify bacteria?
All of the choices are correct.
Sphaerotilus and Leptothrix are examples of
sheathed bacteria
E. coli 0157:H7 produces clear colonies on MacConkey agar, while common strains of the organism produce pink colonies on this medium. The organism stains pink in the Gram stain. Select the TRUE statement, given this information.
E. coli 0157:H7 does not ferment sorbitol AND is Gram negative.
Please use the dichotomous key below to identify a bacterium with the following characteristics: stains pink in the Gram stain, produces no color when exposed to oxidase substrate, and produces both acid and gas when inoculated in lactose broth.
E. coli or other coliform
Which of the following structures would be the best choice as a biological indicator to test autoclave operations?
Endospores formed by Geobacillus stearothermophilus.
From most general to most specific, which is the correct order?
Kingdom, phylum, class, order, family, genus, species
Which of the statements about chemotrophs is FALSE?
Lactic acid bacteria such as Lactobacillus obtain their ATP by oxidizing glucose, using lactic acid as their terminal electron acceptor.
Please select the FALSE statement regarding phenotypic approaches to identifying microorganisms.
MALDI-TOF MS separates and sorts an organism's carbohydrates by mass, generating a profile that provides a fast way to identify an organism grown in culture.
Which of the following statements about members of the family Enterobacteriaceae is NOT true?
Members only reside in the intestinal tract of humans.
Which of the following organisms is the causative agent of Hansen's disease (leprosy)?
Mycobacterium leprae
The Gram-positive rod that is also acid-fast and is a human pathogen is
Mycobacterium tuberculosis.
Intracellular Gram-negative diplococci found in a urethral sample from a male is indicative of
Neisseria gonorrhoeae.
Cyanobacteria have evolved elaborate mechanisms for preventing O2 from coming into contact with the nitrogenase enzyme. Why?
Nitrogenase enzyme complexes are damaged or destroyed by O2.
Why are molecular methods particularly useful for identification of microbes that are difficult to grow?
Since all microbes have DNA, and we can often detect and identify them through even very small amounts of their DNA, molecular methods allow us to identify microbes even when they can't be grown at all.
Which of the following bacteria can oxidize metal compounds exposed during strip mining of coal, dramatically lowering pH and leading to damaging acid run-off into the surrounding ecosystem?
Sulfur-oxidizing bacteria
A sample must contain many microorganisms in order for them to be seen any using microscopy techniques. Why is this so?
The area on a microscope slide is very large compared to the relative size of microbes, and you take a very small amount of your sample to place on the slide surface. Therefore, you must have a large number of microbes initially in the culture to increase the chances that you'll be able to see bacteria on the slide.
When DNA probes are used to identify bacterial DNA similarities by hybridization, the probe DNA is heated and the template DNA is treated to separate the two strands. Why would the probe DNA be heated?
The probe may contain parts that are double-stranded. Heating it up breaks the hydrogen bonds holding the strands together, creating single-stranded sequences that hybridize with their complementary targets.
Please select the FALSE statement regarding sheathed bacteria.
The sheath allows these bacteria to perform photosynthesis.
The purple bacteria are Gram-negative organisms that undergo ______ photosynthesis by using hydrogen sulfide or organic molecules as an electron source, rather than water.
anoxygenic
A unicellular microorganism was recovered from a hot spring (95°C) in Wyoming. After observation, it was determined that the cells lacked a nucleus, had a cell wall that lacking peptidoglycan, and had 70S ribosomes. Analysis of the cytoplasmic membrane revealed lipids containing long-chained branched hydrocarbons with ether linkages. Determine how this organism would be classified, based on the description provided.
archaea
Match each of the following anaerobic chemotrophs with their descriptions.
archea: methanogens found in mud: Sulfur and sulfate-reducing bacteria generally in endospore: Clostridium species GP catalase-negative: lactic acid bacteria GP pleomorphic: Propionibacterium species
The methanogens
are part of the domain Archaea AND oxidize hydrogen gas to produce methane.
Pseudomonas species
are resistant to many disinfectants and antimicrobials and are mostly harmless except for the opportunistic p. aeruginosa
Treponema and Borrelia
are spirochaetes.
Serological methods
are useful in identifying bacteria
Wolbachia are found only in
arthropods
Based on what you know about the myxobacteria, for which of the following could they serve as an experimental model?
cell to cell communication and cooperation
Match the description for each method of nutrient acquisition/retention that may be used by aquatic bacteria.
cells form chains: sheathed bacteria extensions of the cytoplasm: prosthecate bacteria bacteria may prey: predator of other organisms using a special: unusual movement accumulation of sulfur: formation of storage
Reticulate and elementary bodies are two forms in the life cycle of
chlamydia
Which of the following contains bacteriochlorophyll?
chromatium, thiospirillum, thidictyon
Sequencing of rRNA is useful for
determining evolutionary relationships AND identification of unknown bacteria.
In 1970 Stanier proposed that classification be based on
dna sequence
Corynebacterium species and Enterobacteriaceae family members are examples of ______ anaerobes, meaning that they preferentially use aerobic respiration if O2 is available, but can ferment if it is not.
facultative
Gram staining is never sufficient for diagnosis.
false
Obligate aerobes may transform energy via fermentation.
false
Serratia marcescens are red when incubated at 37°C.
false
Streptococcus pyogenes can be easily distinguished microscopically from other Streptococcus species.
false
Swarmer cells are
formed by sheathed bacteria.
Phylogenetic relationships between prokaryotes are most accurately determined using
genotypic information.
Match the description of obtaining nutrients from other organisms with the appropriate organism type.
highly motile: Bdellovibrio species often reside in protozoa: Legionella species form an endo: Some Photobacterium and Vibrio species gram-positive: Epulopiscium species
Which of the following bacteria can oxidize large amounts of ammonia-containing waste, consuming so much oxygen in the process that they can create hypoxic areas of water?
nitrifying bacteria
The conversion of ammonium to nitrate could be accomplished by the presence of
nitrosomonas and nitrobacter
The relatedness of organisms determined by counting common characteristics
numerical taxonomy
It has been estimated that 99% of intestinal bacteria are
obliate anaerobes
If the GC content of two organisms is 60%, the
organisms are most likely related
Clostridium, Lactobacillus, and Propionibacterium all
oxidize organic compounds AND use organic compounds as terminal electron acceptors.
Methanogens are a group of archaea that generate ATP by
oxidizing hydrogen gas, using carbon dioxide as a terminal electron acceptor
Organisms that grow very slowly, cannot be cultured, are present in very small numbers, or are mixed with a number of other bacteria may still be identified using
pcr
Which molecule was the basis for establishing the three-domain classification system?
rRNA
Streptomyces
resemble fungi in their pattern of growth and produce a number of antibiotics
Which of the statements is FALSE?
rhizobia donate some of their dna to the host plant
An early attempt by Cohn at bacterial classification grouped bacteria according to their
shape
The basic taxonomic unit in the classification scheme of plants and animals is
species
Agrobacterium species
stimulate tumor-like growths in plants to obtain nutrients. contain the Ti plasmid that modifies the growth of plant tissue.
Which of the following is NOT associated with a Clostridium species?
strep throat
The role of sulfur in the metabolism of Thiomargarita namibiensis is similar to which of the following in human metabolism?
sugar
When looking at the GC (or G + C) content, a researcher is studying
the dna of the organism
In E. coli O157:H7, the O157:H7 refers to the
the specific LPS and flagella type present.
Disagreements between conclusions obtained from rRNA data and other techniques may be explained by
horizontal DNA transfer.
What roles do hydrogen gas and carbon dioxide play in the metabolism of methanogens?
hydrogen gas in their energy source, and carbon dioxide is their terminal electron acceptor
Which of the following genera have dormant forms that are resistant to extreme environmental conditions? i. Bacillus ii. Clostridium iii. Neisseria iv. Micrococcus v. Leptospira
i. bacillus ii. clostridium
The name Lactococcus (Streptococcus) lactis
indicates that Streptococcus is the old genus name
Helicobacter pylori
inhabit the stomach
Streptococcus pyogenes
is beta-hemolytic.
Which of the following statements about Thiomargarita namibiensis are TRUE?
it stores sulfur, its energy source it stores nitrate, its terminal electron acceptor its name means sulfur pearl of namibia
Members of this group of microbes can break down glycogen deposited in the vaginal lining in response to estrogen. This helps to drop the pH in the area, preventing infections.
lactic acid bacteria
Which of the following microbes is(are) important to cheese-making?
lactic acid bacteria and propinonibacterium
Organisms that typically produce colonies with a fried egg appearance are the
mycoplasmas
A student complains that it makes no sense to worry about coliform bacteria in water, since we naturally have harmless coliforms in our intestines anyway. Is the student correct?
No. While some coliforms might be harmless, their presence serves as an indicator of fecal pollution. Fecally contaminated water may contain a variety of fecal pathogens, not all of which are coliforms.
You have isolated a bacterium from a contaminated river but you are unable to culture it in the laboratory. Which method could you use to identify the organism?
Nucleic acid amplification tests
You are sent three clinical samples and are asked to determine whether they are the same strain. You perform standard identification techniques but cannot come to a conclusion. You decide to do an RFLP test. You digest the genomes of the organisms with the same restriction enzyme and run a gel. Each organism yields 5 bands on the gel, of the following sizes: Organism A: 3 kb, 7 kb, 11 kb; 14 kb, 21 kb; Organism B: 3 kb, 7 kb, 2 kb, 8 kb, 11 kb; Organism C: 11 kb, 3 kb, 14 kb, 7 kb; 21 kb What conclusion(s) can you make from this result?
Organisms A and B are likely the same strain but are different from organism C.
Which of the following about hydrothermal vents is FALSE?
Photosynthesis supports food production in the region.
Which of the following organisms is NOT classified as a facultative anaerobe?
Psuedomonas auruginosa
How do anoxygenic phototrophs benefit from having accessory pigments that allow light to be harvested at deeper areas of a moist or aquatic environment?
This allows even anaerobic microbes to conduct photosynthesis, as they can harvest light energy in the deeper areas where oxygen won't be present, use wavelengths of light not absorbed by the photosynthetic organisms closer to the surface of the water; AND don't have to compete with other cells that use oxygen in the upper levels for the scarce nutrients in the fluid environment.
The lactobacilli, in their role as normal microbiota of the vagina, help the vagina resist infection by contributing to
acidity of the vagina
luminescents
all choices are correct
A selective growth medium
allows only certain bacteria to grow
Thermus and Deinococcus
are both thermophilic
The three domain classification scheme uses
Archaea, Bacteria, Eukarya.
Why might it be easier to identify the bacterium that caused pneumonia than one that caused a wound infection?
Bacteria that cause pneumonia can be identified with few tests because the lungs have no normal microbiota. Many bacteria are normally found on the skin however; these may be in the wound, complicating identification.
The reference for taxonomic descriptions of bacteria is
Bergey's Manual of Systematic Bacteriology.
Which of the following are spirochetes?
Borrelia AND Treponema
Which of the following is/are obligate intracellular parasites?
Chlamydia and Rickettsia
Bacteria that may form endospores include
Clostridium and Bacillus
Select the FALSE statement regarding bacterial diversity.
During unfavorable conditions, myxobacteria travel as a pack to a new location.
Based on DNA hybridization, humans and chimpanzees are the same species.
true
Horizontal DNA transfer may make it more difficult to construct phylogenetic trees.
true
Rhizobium is considered an endosymbiont with plants.
true
The G + C content can be measured by determining the temperature at which double-stranded DNA denatures.
true
The most medically relevant species of Pseudomonas is P. aeruginosa.
true
The skin and oral cavity may have anaerobic microenvironments.
true
The three domain systems consist of Archaea, Bacteria, and Eukarya.
true
You isolate a prokaryote. After performing analysis on the organism, you cannot find a description matching that of your organism in the reference text Bergey's Manual of Systematic Bacteriology. This suggests that you have likely isolated a new organism.
true
Anoxygenic phototrophs
use hydrogen sulfide or organic compounds as a source of electrons.
Media that change color as a result of the biochemical activity of growing bacteria
usually contain pH indicator
Woese
was involved in determining rRNA sequences AND proposed breaking prokaryotes into two groups.
