Microbiology CH 9

The following are steps used to make DNA fingerprints. What is the third step?

Digest with a restriction enzyme.

In the figure, the bacteria transformed with the recombinant plasmid and plated on media containing ampicillin and X-gal will

form white, ampicillin-resistant colonies.

Biotechnology involves the

use of microorganisms to make desired products, the use of animal cells to make vaccines, and the development of disease-resistant crop plants.

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 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 Bt toxin could result in the death of non-pest species of insects.

Arrange the following statements in chronological order.

1. The Ti Plasmid is isolated and prepared for the insertion of foreign DNA 2. The gene fot Bt toxin is isolated from the bacterium and inserted into the plasmid 3. the plasmid is taken up by a bacterium 4. the bacterium is used to introduce the Bt toxin gene into the chromosome of plant cells 5. a single plant cell is chosen to produce a plant that now produces Bt toxin

Consider the double-stranded DNA molecule below. The gray segments in the middle represent the regions we'd like to amplify by PCR. Four different pairs of PCR primers (in blue) are shown below. Each primer is shown in the location it would anneal to its template strand. Which primer pair would best amplify the target region?

1 Two features make this primer set the best choice for amplifying the target region. First, their 3' ends face the sequence to be amplified. This is crucial, because DNA polymerase only adds nucleotides to the 3' end of the primers. Any other orientation would not duplicate the target sequence! Second, the primers bind right at the end of the target sequence. This is desirable, because it means that only the target sequence will be amplified, and not the surrounding sequence(s) as well.

Which of the following places the steps in the PCR procedure in the correct order?

1) Incubate at 94°C to denature DNA strands; 3) Incubate at 60°C for primer hybridization. 2) Incubate at 72°C for DNA synthesis;

The following tiles indicate the first five thermocycler steps in a PCR run. Arrange them in the correct order.

1. 94∘C for 1 minute 2. 55∘C for 1 minute 3. 72∘C for 1 minute 4. 94∘C for 1 minute 5. 55∘C for 1 minute

Arrange the following steps from a typical genetic modification procedure into their correct sequence. Place the first step at the far left. Some steps may be equivalent.

1. Isolate Bacterial Plasmid 2. Select gene of interest + insert into plasmid 3. Plasmid taken up by bacterium 4. Bacteria Replicate 5. Cloned gene harvested from bacteria.

In the figure, after digestion with the appropriate restriction enzyme, what is the smallest piece containing the entire ampicillin-resistance (amp) gene?

1.50 kbp

How many pieces will EcoRI produce from the plasmid shown in the figure?

2

The following steps must be performed to make a bacterium produce human protein X.

6-Eukaryotic transcription 7-Reverse transcription 2-Restriction enzyme 4-DNA ligase 5-Transformation 3-Prokaryotic transcription 1-Translation

Each step of the polymerase chain reaction is associated with a particular temperature.

72C = DNA extension 55C= Primer annealing 94C= DNA denaturation

You have a small gene that you wish replicated by PCR. After 3 replication cycles, how many double-stranded DNA molecules do you have?

8

The Pap test for cervical cancer involves microscopic examination of cervical cells for cancerous cells. A new, rapid diagnostic test to detect human papilloma virus (HPV) DNA before cancer develops is done without microscopic exam. The steps involved in this FastHPV test are listed below. What is the second step?

Add an RNA probe for HPV DNA.

Which statement regarding agricultural biotechnology is FALSE?

Agricultural biotechnology is extremely limited because foreign genes cannot be inserted into plant cells.

The restriction enzyme EcoRI recognizes the sequence GAATTC. Which of the following is TRUE of DNA after it is treated with EcoRI?

All of the DNA fragments will have single-stranded regions ending in AA.

Which of the following best describes how recombinant DNA technology currently helps patients who do NOT produce adequate amounts of growth hormone (hGH)—a condition that otherwise leads to stunted growth?

Bacteria now produce hGH.

Which of the following best describes why a vector is used in genetic modification procedures?

Cells usually won't copy an isolated gene sequence.

Which of the following are used by the Centers for Disease Control and Prevention to track outbreaks of foodborne disease?

DNA fingerprints, restriction fragment length polymorphisms, and reverse-transcriptase PCR(rtPCR)

Which of the following attaches the target gene to a desired location?

DNA ligase

Suppose the thermocycler is INCORRECTLY programmed to omit the 72∘C step in each cycle of an otherwise normal PCR run. Which of the following would most likely occur?

DNA polymerase would synthesize DNA more slowly.

In the figure, the enzyme in step 2 is

DNA polymerase.

Which of the following best describes why PCR protocols contain numerous cycles of the denaturation/annealing/extension steps?

Each cycle of PCR doubles the amount of DNA synthesized, but the number of copies starts out small. Numerous cycles are required to produce a sufficient number of copies.

The practice of breeding plants and animals for desirable traits, such as high crop yield, is called natural selection.

False

The term biotechnology refers exclusively to the use of genetically engineered organisms for the production of desired products.

False

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

Why would a recombinant DNA molecule be inserted into a host cell?

It can be copied, transcribed, and translated into a desired protein.

Which of the following statements about recombinant DNA technology is FALSE?

It has limited application because genes of interest cannot be moved from one type of cell to another.

Which of the following is an advantage of using E. coli to make a human gene product?

Its genes are well known.

Why is PCR a valuable technique?

PCR creates large amounts of DNA from minute source quantities.

Recombinant DNA techniques typically involve generating a clone. Why?

Producing a clone generates many copies of the gene of interest.

Which of the following are used to silence specific genes and hold promise for treating cancer or viral diseases, such as hepatitis B?

RNA interference (RNAi)

In the figure, the enzyme in step 1 is

RNA polymerase.

What does a thermocycler do?

Subjects samples to temperature changes

Which of the following best explains how scientists are able to introduce the bacterial gene for Bt toxin into the cotton plant genome?

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.

Which statement best describes restriction enzymes?

They are important for cloning applications because they can be used to cut DNA at specific nucleotide sequences.

How do restriction enzymes cut DNA sequences?

They cut DNA at sites, called recognition sites, that have specific nucleotide sequences.

After the 94∘C step, why must the thermocycler reduce the temperature to 55∘C?

To allow primers to bind to the DNA template strands

In general, how might recombinant DNA technology be used to prevent a genetic disorder caused by a mutation in a single gene?

To insert a desirable gene, remove an undesirable gene, or replace a defective gene with a functioning gene

Which of the following best describes the purpose of primers in PCR?

To provide a structure from which DNA can be synthesized

In recombinant DNA technology, a vector is a self-replicating segment of DNA, such as a plasmid or viral genome.

True

One of the first commercial successes of recombinant DNA technology was the production of human insulin using genetically engineered E. coli.

True

Why is baker's yeast useful for expressing genetically engineered genes?

Yeast cells are eukaryotic and so would likely be successful in expressing eukaryotic genes.

Which of the following best describes a clone in the context of genetic modification procedures?

a culture of genetically identical cells

A restriction fragment is

a segment of DNA.

In the Southern blot technique, which of the following is NOT required?

addition of heat-stable DNA polymerase to amplify DNA

In PCR, it is important to use Taq DNA polymerase, as opposed to other DNA polymerases. This is because Taq is capable of synthesizing DNA _________.

after exposure to 94∘C

A population of cells carrying a desired plasmid is called a

clone.

The figure at the left in the figure shows a gene identified by Southern blotting. What will a Southern blot of the same gene look like after PCR?

d black square in the midle

A colleague has used computer modeling to design an improved enzyme. To produce this enzyme, the next step is to

determine the nucleotide sequence for the improved enzyme.

The use of an antibiotic-resistance gene on a plasmid used in genetic engineering makes

direct selection possible.

The random shotgun method is used in

genome sequencing.

An advantage of synthetic DNA over genomic or cDNA is the ability to

insert desired restriction sites into the DNA sequence.

If you have inserted a gene in the Ti plasmid, the next step in genetic engineering is

inserting the Ti plasmid into Agrobacterium.

An advantage of cDNA over genomic DNA is that it

lacks introns.

The study of genetic material taken directly from the environment is

metagenomics.

Which of the following techniques is NOT used to introduce recombinant DNA into plants?

microinjection

PCR can be used to identify an unknown bacterium because

the RNA primer is specific.

Which of the following methods would be used to introduce the plasmid shown in the figure into E. coli?

transformation

Self-replicating DNA used to transmit a gene from one organism to another is a

vector.