(Ch 12, 25) Pearson HW Questions

Chapter 12, 25,

Which of the following is NOT an example of synthetic biology?
a.) assembling gene sequences together into genome and creating a living organism from it.
b.) making E. coli photographic
c.) developing a novel polyvalent vaccine
d.) creating a new metabolic pathway that produces a previously unidentified compound

c.) developing a novel polyvalent vaccine

Which of the following is NOT a limitation to using auxotrophs to prevent the spread of genetically modified genes to wild populations?
a.) auxotrophs may mutate in ways that allow them to synthesize the limiting nutrient
b.) auxotrophs often cross-feed from the metabolites of other organisms in the environment
c.) back mutation to the wild type may occur
d.) auxotrophs self-destruct using self-toxins when this method is applied

d.) Auxotrophs self-destruct using self-toxins when this method is applied.

A poorly immunogenic vaccine often suggests the foreign proteins were not properly recognized by the immune system due to a lack of ________ necessary, which can also be engineered to occur with additional molecular manipulations.

glycosylation

The Ti plasmid is best suited for genetically manipulating
a.) plants
b.) Agrobacterium spp.
c.) viruses
d.) fish

a.) plants

One challenge in cloning human somatotropin is that

it is susceptible to digestion by bacterial proteases because it is a small protein hormone

Plasmids are commonly used as cloning vectors because __________.
a.) they are easily inserted into cells by transformation
b.) they can contain genes for antibiotic resistance used for plasmid selection.
c.) they can replicate independently of the chromosome
d.) all of the listed responses are correct.

d.) all of the listed responses are correct

Genetically engineered vaccines can be created by __________.
a.) adding virulence genes from a pathogen to a non-virulent organism
b.) removing virulence genes from a pathogen
c.) purifying a specific subunit of a pathogen
d.) all of the listed responses are correct.

d.) all of the listed responses are correct

Benefits of transgenic plants include __________.
a.) herbicide susceptibility
b.) decreased yield
c.) insect resistance
d.) shorter shelf life

c.) insect resistance

Polyvalent vaccines using vaccinia virus are highly favored by doctors and physicians, but are especially challenging for those who develop them, because

multiple foreign proteins simultaneously synthesized often disrupts each other’s activity

The principle underlying how salmon were genetically engineered to grow faster is the

replacement of inducible to constitutive hormone production

Bt crops, including potatoes and cotton, are genetically engineered using laboratory techniques. Which of the following utilizes recombinant DNA technology to produce advantageous traits in the crops that are produced?

Genetically engineered crops have an advantageous gene from another organism inserted into their genome.

Bt crops are engineered in the lab to produce Bt toxins due to the presence of a bacterial gene from B. thuringiensis. Why is it advantageous for the plants to produce the Bt toxin?

Insects that normally destory non-toxin-producing crops will be killed when they eat plants that do produce the toxin. 

Which of the following best explains how scientists are able to introduce the bacterial gene for Bt toxin into the cotton plant genome?
a.) The bacterial gene for Bt toxin is isolated, and the DNA is put into tiny bullets (like BB’s) that are “shot” into the cotton plant using a gene gun.
b.) The Bt toxin gene is isolated and inserted into a Ti plasmid from Agrobacterium tumefaciens. The engineered Ti plasmid is taken up by a bacterium that infects the cotton plant.
c.) A virus is engineered to contain the Bt toxin gene. This virus is then used to infect the plant and pass on the gene.
d.) The Bt toxin gene is added to water that is sprayed on the cotton plants. The gene is taken up through the roots of the plant

b.) The Bt toxin gene is isolated and inserted into a Ti plasmid from Agrobacterium tumefaciens. The engineered Ti plasmid is taken up by a bacterium that infects the cotton plant.

GM crops have raised issues among communities in which they are produced. Which of the following are concerns raised by the public about genetically engineered crops?

-The Bt toxin could result in the death of non-pest species of insects.
-The Bt gene could ultimately make the plants pathogenic to humans.
-The Bt toxin could negatively affect the taste of the food that is produced from these crops.

The cells used as hosts for cloning vectors are __________.

easy to grow and transform with engineered DNA

True or false: Engineering a metabolic pathway enables a researcher to use different genes from unrelated organisms.

False

It is possible to rapidly screen for mutations in regulatory genes using

gene fusions

Recognizing pathogens that contain multiple unique proteins which enable the human immune system to recognize just one and mount an effective response has opened the door on development of some vaccines only being

subunit vaccines

What is the first step in constructing a metagenomic library from RNA?

The RNA must be converted into cDNA, using reverse transcriptase. 

A researcher wanted to determine the LD₅₀ (lethal dose that kills 50% of the infected hosts) for a newly isolated bacterial pathogen. Mice were inoculated with diluted cultures containing between 10¹ and 10⁷ cells. After two days, all of the mice had died EXCEPT for the uninoculated controls. Which of the following is the most likely explanation?
a.) This pathogen is highly virulent in mice
b.) Mice are not good model animals for this pathogen.
c.) The pathogen has become attenuated.
d.) The pathogen has a very high LD₅₀.

a.) This pathogen is highly virulent in mice

Pathogenicity is the ability…

of the pathogen to inflict damage on the host

Siderophores are…

Organic molecules that help pathogens take up iron.

Which of the following is most likely to cause disease?

a.) injection of 10¹ cells of a highly virulent bacterial species into a mouse.
b.) injection of 10⁵ cells of a highly virulent bacterial species into a mouse.
c.) injection of 10⁶ cells of a low virulent bacterial species into a mouse. 
d.) injection of 10³ cells of a moderately virulent bacterial species into a mouse. 

b.) injection of 10⁵ cells of a highly virulent bacterial species into a mouse.

________ is a damage or injury to a host organism that impairs its function.

Disease

Which of the following is NOT important for the adherence of bacteria to host tissues?
a.) capsule
b.) adhesins
c.) lipopolysaccharides
d.) slime layer

c.) lipopolysaccharides

The best term to describe the general process by which microorganisms cause diseases is known as…

pathogenesis

For several months a graduate student has been working with a pure culture of a suspected bacterial pathogen in an attempt to determine whether it causes disease in various animal models. She had initially found that the organism was highly virulent in mice, but when she attempted to replicate her early experiments weeks later, all of the new experimentally infected mice survived. The student has brought her surprising findings to the lab's weekly research meeting. What advice could you give her?

The bacterial strain may have become attenuated. 

A pharmaceutical company that uses the Limulus amoebocyte lysate (LAL) assay to test water that is used to make sterile saline for intravenous administration is trying to detect small amounts of which of the following?

endotoxin

Endotoxins are also known as…

Lipid A

When would endotoxins be released from a bacterial cell?

When the cell dies

Which of the following would be the first sign of an infection that resulted in the release of endotoxin?
a.) Weakness
b.) Nausea
c.) Fever
d.) Pain

c.) Fever

Why is a release of endotoxin into the bloodstream potentially deadly?

It can lower blood pressure and cause the patient to go into shock.

Certain traits that allow pathogens to create infection and cause disease are termed

virulence factors

Which of the following enzymes breaks down the “glue” that holds cells together?
a.) Collagenase
b.) Streptokinase
c.) Fibrinolysin
d.) Hyaluronidase

d.) Hyaluronidas

Which of the following virulence factors would be found in Staphylococcus aureus?
a.) Streptokinase
b.) Collagenase
c.) Staphylokinase
d.) Hyaluronidase

c.) Staphylokinase

How do fibrinolysins enhance a pathogen's virulence?

They break down fibrin proteins that are involved in clot formation, allowing the cells to penetrate deep into damaged skin.

Which of the following features of Salmonella prevent it from being phagocytosed?

Flagella

Where do Salmonella pathogens grow and replicate in the infected host?

Inside phagocytes

Where is the site of Shigella attachment in the host?

M cells

How do Shigella cells move between host cells?

They can polymerize actin molecules from the epithelial cells into tail-like structures that propel them from one cell to another. 

What is the etiologic agent of typhoid

Salmonella

An exotoxin that has the ability to kill or damage host cells is referred to as a(n)

cytotoxin

Which domain of the A-B toxin binds to cell surface receptors on the host cell?

B domain

How are superantigens different from other types of exotoxins?

Superantigens cause an overstimulation of the host immune system.

A person who attended a picnic early in the day develops a very high fever and is unresponsive by the evening. This person most likely has been exposed to a…?

superantigen

A patient who has been hospitalized with uncontrolled muscle spasms has probably been infected with bacteria that secrete a…?

neurotoxin

How does the dental bacteria plaque stay in place?

-Bacteria may use dextran as an adhesive.
-Bacteria may use capsule adhesins to adhere to glycoproteins.
-Saliva glycoproteins form a film to which bacteria can attach.

Dental plaque consists of a biofilm, with bacteria carefully arranged in a community. What are the advantages of forming a biofilm?

Biofilms provide protection from immune attack. 

What steps are involved in the formation of dental plaque? Put the steps in order from the first to last.

1.) A thin film of glycoproteinis deposited on teeth by saliva

2.) S. sobrinus uses capsule adhesins to attach to glycoproteins, and S. mutans uses dextran to attach to enamel within crevices.

3.) Bacteria ferment glucose, producing lactic acid.

4.) Dental caries form

5.) Periodontal disease or other infections can develop.

_ is needed for dental plaque formation, because it is used to produce bacterial capsules.

Sucrose

_ is fermented to produce the lactic acid that dissolves enamel on teeth.

Glucose

_ is an archaean found in dental plaque.

Methanobrevibacter oralis

_ is a common bacterial species found in dental plaque.

Streptococcus sobrinus

_ are produced as acid dissolves tooth enamel.

Caries

_ is the condition in which bacteria are found in the blood.

Bacteremia

_ is the condition in which bacteria are reproducing in the blood and spreading.

Septicemia

Although it had been thought that dental plaque consisted primarily of streptococci, more recent research showed that a variety of microbes are present. What approaches were used to identify these additional microbes and to determine their three-dimensional structure in the biofilm?

phylogenetic probes/fluorescent in situ hybridization

Newer molecular approaches have made it possible to identify a wide range of species that cannot currently be cultured in the laboratory. FISH also allows the structure of the community to be visualized.