Chapter 18 Mastering Microbiology
Microarrays are useful for assessing gene expression. gene expression and the presence of specific rRNA sequences. the presence of specific rRNA sequences. enzyme activity.
gene expression and the presence of specific rRNA sequences.
Which fluorescent molecule enables visualization of living microorganisms? SYBR® Green GFP acridine orange DAPI
GFP
The element(s) that have proven useful for stable isotope studies are carbon. sulfur. carbon, nitrogen, and sulfur. nitrogen.
carbon, nitrogen, and sulfur.
Phylogenetic stains, such as those used in FISH, hybridize with RNA polymerase. nuclear DNA. ribosomal RNA. mitochondrial DNA.
ribosomal RNA.
In natural samples it is often difficult to differentiate live cells from dead cells or cells from nonliving matter. True False
true
Several fluorogenic dyes can be used simultaneously in a sample as long as they each emit light at a different measurable wavelength. True False
true
A NASA ecologist wants to design an instrument to send to Mars on the next space probe to determine whether living organisms ever carried out carbon fixation on that planet. Suggest an assay that she could use on Martian soil samples. 34S/35S stable isotope analysis MAR-FISH NanoSIMS 13C/12C stable isotope analysis
13C/12C stable isotope analysis
When dealing with stable isotopes, enzymes tend to favor the lighter isotope. either the lighter or the heavier isotope, depending on environmental conditions. the isotopes in about equal proportions. the heavier isotope.
the lighter isotope
Which of the following statements is FALSE concerning enrichment bias? Dilution of the inoculum may help to avoid enrichment bias in some cases. Enrichment bias resulted in the underestimation of prokaryotic diversity. Enrichment bias is impossible to overcome in some oligotrophic environments. Enrichment bias favors organisms that grow quickly.
Enrichment bias favors organisms that grow quickly.
Once a putative pure culture has been obtained from the environment, it is no longer necessary to check its purity. True False
False
How do viability stains usually distinguish between living cells and dead cells? The chemical fluoresces only when bound to ribosomes that are actively synthesizing proteins. The dye's fluorescence is quenched by dead cells. The chemical stain is taken up by living cells and once metabolized becomes fluorescent. The dye specifically targets intact cytoplasmic membranes.
The dye specifically targets intact cytoplasmic membranes.
There is a small lake on campus that students like to use for recreational activities. A study has begun on the microbial community in the lake at different times of the year. In order to quickly determine the approximate number of reproducing bacteria in a sample, it would best to use __________. green fluorescent protein reporter genes a fluorescent nucleic acid stain a fluorescent viability stain a Gram stain
a fluorescent viability stain
Winogradsky columns are used primarily for enrichment of anaerobic cultures, although occasionally aerobes do appear. aerobic cultures, although occasionally anaerobes do appear. phototrophs, although occasionally heterotrophs do appear. aerobes, anaerobes, and phototrophs.
aerobes, anaerobes, and phototrophs.
Analyses of sulfur isotopes have been used as evidence against life on the Moon, because the sulfides in lunar rocks have an isotope composition similar to marine sulfate, which is enriched in 34S. exactly equal amounts of 34S and 32S. an isotope composition similar to marine mud, which is depleted in 34S. an isotope composition similar to igneous rocks.
an isotope composition similar to igneous rocks.
You would like to determine the rate of production of carbon dioxide in a specific microbial habitat. How could you do this without growing the microorganisms in the lab? by using radiolabeled methane by using radiolabeled DNA by using a microsensor by using radioisotope-labeled carbon dioxide
by using a microsensor
The methodology of microbial ecology includes enrichment and isolation of specific microbes. gene, transcript, and protein characterization. cell-staining methods. enrichment and isolation of specific microbes, cell-staining, and gene, transcript, and protein characterization.
enrichment and isolation of specific microbes, cell-staining, and gene, transcript, and protein characterization.
The diversity of microorganisms in culture collections is representative of the diversity of microorganisms found in nature. True False
false
What technique(s) can be used to characterize the phylogenetic composition of a microbial community without culturing any of the members? green fluorescent protein tagging radioisotope experiments fluorescent in situ hybridization stable isotope techniques
fluorescent in situ hybridization
Which molecular method allows for the detection of a specific organism within a diverse microbial community? viability staining fluorescent in situ hybridization fluorescent DNA staining using DAPI enrichment techniques
fluorescent in situ hybridization
Metatranscriptomics and metaproteomics are favored over metagenomics when ________ is of more interest than ________. gene presence / function or gene expression gene presence / phylogeny function or gene expression / gene presence phylogeny / gene presence
function or gene expression / gene presence
The term axenic is used to describe a(n) pure culture. anoxygenic culture. nutritionally deficient culture. anaerobic culture.
pure culture
For microbial biodiversity studies, it is common to identify the ________ rather than the ________ as a measure of biodiversity. organisms themselves / genes cell types / genes cell types / organisms themselves genes / organisms themselves
genes / organisms themselves
The biggest limitation of traditional light microscopy and electron microscopy methods is that they are unable to reveal absolute cell concentration. genetic and functional diversity of microorganisms in the habitat under study. cellular components of small microbes because of the limits of magnification. physical microbial interactions as found in nature.
genetic and functional diversity of microorganisms in the habitat under study.
Culture-independent approaches avoid issues associated with detecting very rare phylotypes. growing organisms in the lab. conflating phylogenetic and functional diversity. next generation sequencing.
growing organisms in the lab.
The science of microbial ecology deals with how microbial communities interact with each other and their environment. microbial activity and biodiversity. how the activity and biodiversity of microbial communities affect microbial interactions with each other and the environment. microbial gene regulation mechanisms in response to environmental change.
how the activity and biodiversity of microbial communities affect microbial interactions with each other and the environment.
The phylogenetic analysis of complex microbial communities often targets small subunit (SSU) ribosomal RNA genes. This is because rRNA is found in all organisms and __________. is highly conserved over evolutionary time is made by cells only at certain times is easier to extract from samples has more genes than mRNA
is highly conserved over evolutionary time
Which approach would help to identify biologically produced sulfur in a sediment sample? Which approach would help to identify biologically produced sulfur in a sediment sample? isotopic fractionation microautoradiography enrichment microelectrodes
isotopic fractionation
Select the option that lists the steps necessary for PCR microbial community analysis in the correct order. microbial sample collection; sorting by electrophoresis; analysis; DNA extraction; PCR of target genes PCR of target genes; microbial sample collection; DNA extraction; sorting by electrophoresis; analysis microbial sample collection; PCR of target genes; DNA extraction; sorting by electrophoresis; analysis microbial sample collection; DNA extraction; PCR of target genes; sorting by electrophoresis; analysis
microbial sample collection; DNA extraction; PCR of target genes; sorting by electrophoresis; analysis
Which technique would be used to estimate the concentration of naturally occurring Escherichia coli in a wastewater sample? laser tweezers method most probable number (MPN) method cell tagging using GFP method agar dilution tube method
most probable number (MPN) method
The best choice for estimating the viable cell number of a water sample would be the __________. spectrophotometric method agar dilution tube method most probable number method streak plating method
most probable number method
What is the process that will amplify DNA from a single cell isolated from a natural microbial community? multiple displacement amplification polymerase chain amplification polymerase chain reaction You cannot amplify the DNA from a single cell isolated from an environmental sample.
multiple displacement amplification
Microarrays that have been designed to screen samples for specific groups of bacteria are called __________. biochips microchips phylochips phytochips
phylochips
Genes that change over evolutionary time as organisms diverge are called orthologs. Organisms with identical or very similar orthologous genes belong to the same __________. ribotype phenotype genotype phylotype
phylotype
Metagenomics involves the analysis of a microbial community by __________. sampling and sequencing all of the genes in an environment sequencing all of the community RNA in an environment generating a phylogenetic tree based on all of the versions of a gene in an environment generating a complete sequence of the genomes of all of the organisms in an environment
sampling and sequencing all of the genes in an environment
Enrichment cultures are often effective for isolating bacteria from complex communities in natural samples because they __________. select for certain bacteria do not select for or against any bacteria; they help every organism to grow select both for and against certain bacteria select against certain bacteria
select both for and against certain bacteria