M Bio Exam 4 (9,28,29,30)
If you did a cloning experiment but you accidentally left x-gal out of the medium you use to grow your transformants, what would be the result (assuming you remembered all other important ingredients in your culture medium, including ampicillin)?
All cells that grow would produce white colones.
Please identify the mismatched pair regarding waste water treatment.
Ammonia stripping - Removal of free gaseous ammonia from water.
Key Terms Summary: Match the term with its definition
Anaerobic Digestion: Process that uses anaerobic microbes to degrade the sludge obtained during wastewater treatment. Advanced Treatment: Any physical, chemical, or biological purification process beyond secondary treatment of wastewater Sludge: The solid portion of wastewater that settles to the bottom of sedimentation tanks during primary and secondary treatment. Composting: The natural decomposition of organic solid material. Wastewater: Material that flows from a household or business plumbing system; also includes storm runoff water and some industrial wastes Effluent: The liquid portion of treated wastewater. Biochemical Oxygen Demand (BOD): The amount of oxygen required for the microbial decomposition of organic matter in a sample
If you want to use PCR to generate the target sequence indicated by the gray box in the figure below, DNA primers that have the complementary sequence for which sections are required?
B and C
How does boiling a home-canned food immediately before serving it prevent botulism?
Botulinum toxin is denatured by heat, becoming harmless.
Please select all of the foods and beverages from the list below that are produced by microbial fermentation.
Bread yogurt and cheese beer and wine pickles
What creates the air pockets in bread?
CO2, produced through fermentation by Saccharomyces cerevisiae.
Match each method for studying microbial communities with its description.
DNA microarrays: Comparing microbial populations by studying gene expression. Fluorescence in situ hybridization (FISH): Using fluorescent probes to look for specific microbes in an area/community. Metagenomics: Using microbial DNA sequence information to observe commonly conserved genes for particular traits.
Which of the restriction enzymes would be used to cut the sequence CATGTGTGAATTCTGATA?
EcoRIc
Please match the words with their appropriate definition.
Ecosystem: Community of organisms and the non-living environment with which they interact Community: All of the different organisms in a location Ecology: Study of the interaction of organisms with each other and their environment Population: Organisms of the same type in a given environment Ecological niche: Role of an organism in a particular ecosystem Microenvironment: Environment immediately surrounding an individual microbe Biosphere: All of the ecosystems on Earth
The figure below shows the recognition sequences and cutting sites of two different restriction enzymes. If you are trying to clone gene X, which enzyme would you use to cut your DNA fragment and the cloning vector (A or B) and why?
Enzyme B, because it creates staggered "sticky ends" and complementary sticky ends anneal easily. Correct
Which of the following is NOT part of the nitrogen cycle?
Fermentation
Please select the statement that best describes the purpose of gel electrophoresis.
Gel electrophoresis separates DNA fragments based on size.
Which of the following is NOT a method used to detect fecal coliforms in drinking water?
Gram stain
The growth and metabolism of organisms themselves can alter an environment dramatically. Why?
Nutrients may become depleted, and a variety of potentially toxic waste products may accumulate.
Which of the following is NOT used for secondary waste water treatment?
Oceans
Which of the following are advantages of using PCR for disease diagnosis?
PCR can be used to detect anaerobic pathogens which would require special culture conditions. PCR allows a patient to receive treatment quicker .PCR allows for quick detection and identification of organisms that grow slowly in culture.
When cloning eukaryotic genes into bacteria for protein production, a copy of DNA that lacks introns must first be obtained. Introns are removed from primary RNA transcripts by the cell's own machinery, but the copy of the DNA lacking introns must be generated by a biotechnology method. This intron-free copy DNA (or cDNA) is generated by
obtaining mRNA from the cell, then using reverse transcriptase enzyme to convert it into a stable cDNA (or copy of DNA) molecule for insertion into the bacterial cell.
What properties should a cloning vector have?
origin of replication, restricition enzyme recognition site, selectable marker, second genetic marker
Please select all methods of food preservation from the list.
drynig lowering pH salt + sugar pasteurization
Bacteriocins are ______ produced by bacteria that kill off closely related strains, thereby reducing competition in a low-nutrient area.
proteins
An important goal of wastewater treatment is to decrease the environmental impact by ______ the biochemical oxygen demand (BOD).
reducing
Look at the figure below. The bacterial colonies, shown here on medium containing ampicillin and x-gal, are different colors because
some colonies have bacteria that cleaved x gal while others did not some colonies have bacteria that have non functional lacZ gene while others do not some colonies have bacteria that produce a functional lac Z gene while others do not some colonies have bacteria that have a recombinant plasmid in them while others do not
Most bacteria require an aw (water activity) above 0.90 for growth. Which of the following is likely to spoil quickest?
fresh stew - aw 0.98
Microbes growing in nodules on the roots of plants can form an agriculturally important symbiotic ______-fixing relationship. Microbes in this group are collectively referred to as rhizobia.
nitrogen
A specimen from a vaginal sample is subjected to polymerase chain reaction. Primers specific for a gene in the bacterium Neisseria gonorrhoeae are used in the reaction, and an amplified DNA product is visualized on an agarose gel. This can lead a physician to conclude that
the patient is infected with Neisseria gonorrhoeae.
The tart taste of yogurt, pickles, sharp cheeses, and some sausages is due to
the production of lactic acid as a by-product of fermentation in these foods by bacteria.
Low biochemical oxygen demand (BOD) indicates that
there is a small amount of degradable material present in the water and little oxygen is being consumed by microbes.
Match the food product with the description of how it is produced.
Acidophilus milk: A culture of L. acidophilus is added immediately before packaging. The microbes are included for a possible health benefit in the human intestinal tract. Yogurt: Pasteurized milk is inoculated with Streptococcus thermophilus, then incubated at 40-45° C for several hours under controlled conditions to alter the milk's consistency and flavor. Cheese: Pasteurized milk is inoculated with Lactococcus cremoris and L. lactis, then incubated until fermentation products cause the milk proteins to coagulate.
Which of the following cause foodborne intoxications?
Staphylococcus aureus Clostridium botulinum
What are mycorrhizas?
The fungi growing on plant roots that help the plants take up phosphorus and other substances in exchange for plant nutrients.
Which of the following are disadvantages of sanitary landfills for waste management?
There are only a limited number of available urban/suburban sites for landfills. Methane gas accumulates in landfills, and must be removed. There is some risk that pollutants may leak from a landfill into underground aquifiers.
Identify what researchers can learn about a microbial community using metagenomics.
They can identify the genes that are present in a microbial community. Knowing what genes are present in a community may facilitate identification of microbes. They may learn what role a particular microbe has in the environment.
Please select the FALSE statement regarding mycorrhizas
They grow as endosymbionts within specialized organs called nodules.
Which of the following are critical in ensuring that a septic tank works properly?
They must drain adequately Drainage from the system should be distant from water supplies. Sludge that remains in the septic tank must be pumped out from time to time.
Why would adding soil and water facilitate composting?
To add a variety of microbes to the system, and moisture to support their growth.
In the dideoxy chain termination (Sanger) method of DNA sequencing, when ddNTP (dideoxynucleotide) is incorporated into a growing DNA strand, elongation will stop.
True
Microbes growing in low-nutrient environments typically do so in biofilms—nutrients accumulate on the surface of these structures.
True
Nitrogen fixation and ammonification are two different reactions in the nitrogen cycle that yield ammonium as a product
True
The metabolism of lactic acid bacteria differs from that of most other microorganisms that can grow aerobically in that wost organisms that grow aerobically use aerobic respiration, lactic acid bacteria only ferment.
True
The sulfur cycle resembles the carbon cycle more than the nitrogen cycle in that sulfur is mostly in solid form and originates from natural sedimentary deposits rather than from the atmosphere.
True
The use of starter cultures improves the safety of fermented meat products by increasing the number of microbes that create acidic end products, thereby inhibiting the pathogens that otherwise might grow.
True
To make fermented sausages, meat is ground and combined with a starter culture and other ingredients (including sugar, salt, and nitrite). The sugar serves as a substrate for fermentation by the microbes since there isn't enough sugar for this process in the meat itself.
True
Select the statement that best describes why we test for coliforms when determining the quality and safety of drinking water.
When there are coliforms, other intestinal pathogens may also be present.
Spoiled foods are
any foods that have undergone an undesirable change due to microbial growth.
Restriction enzymes are
bacterial in origin DNA cleaving enzymes
A bioremediation strategy called ______ enhances growth of local microbes in a contaminated site by providing additional nutrients.
biostimulation
Consider the figure below. Bacteria containing the plasmid shown in panel A would generate ______ colonies on medium containing x-gal, while those in panel B would generate ______ colonies.
blue; white
Please choose the statement that best describes the role of a cloning vector.
Introduce DNA into a cloning host.
Which of the following are mutualistic relationships?
Microbes in digestive organs of herbivores Rhizobia in legume root nodules. Mycorrhizas in/on plant roots.
Why do xenobiotics often persist in the environment?
Microorganisms are unlikely to have the enzymes to break them down.
Correctly place the steps in the commercial production of wine.
Picture
Key Concept Activity: Match the following municipal wastewater treatment methods with their descriptions.
Picture
Label the figure to identify all the potential environmental sources of groundwater contamination.
Picture
Label the general components of a constructed wetland to better understand the production of cleaner water. Not all labels are used.
Picture
Please choose the correct statement that describes the actions of methanogens in the carbon cycle.
Produce methane in anaerobic ecosystems
Which microbial groups are most likely to spoil refrigerated foods?
Psyhrophiles Psychrotrophs
Please match the food preservation method with its description.
Refrigeration: Use of lowered temperatures to slow growth of microbes in food. Lowering pH: Adding acids or encouraging fermentation to push microbes out of their optimal range for growth. Cooking: Use of high heat for extended time to kill microbes; alters food considerably. Freezing: Lowering temperature enough to form ice crystals that damage or kill microbes. Pasteurization: Exposing foods to high temperatures for short times to reduce numbers of spoilage microbes. Irradiation: Exposing food to gamma rays to destroy microbes without altering the flavor of foods. Adding antimicrobial chemicals: Adding organic acids, nitrates, or sulfur dioxide to inhibit microbes Canning: Use of steam heat under pressure. Especially useful for eliminating endospores. Drying/reducing aw: Removing water or adding salt/sugar, thereby reducing available water.
Please choose the statement that best describes the role of restriction enzymes in genetic engineering.
Restriction enzymes are used to cut DNA at specific locations.
Identify the factors that result in streams and rivers generally being aerobic.
Rivers and streams flow rapidly and are turbulent, facilitating O2 circulation. Rivers and streams can be shallow, allowing light to penetrate to the bottom and facilitating photosynthesis throughout the water body.