Mastering Biology: Chapter 20

The segment of DNA shown in the figure has restriction sites I and II, which create restriction fragments A, B, and C. Which of the gels produced by electrophoresis best represents the separation and identity of these fragments?

C ----- A - B

In recombinant DNA experiments, what is used to cut pieces of DNA and what joins the resulting fragments to form recombinant DNA?

a restriction enzyme ... DNA ligase

cDNA is synthesized from what molecule using an enzyme known as what?

mRNA ... reverse transcriptase

In gel electrophoresis DNA molecules migrate from _____ to _____ ends of the gel.

negative ... positive

Which of the following processes is most like the formation of identical twins?

organismal cloning

Part A video

phosphate

Which of the following information or processes does gene therapy require?

the ability to introduce the normal allele into the patient

Part E video

the profile from suspect 2 matches the crime scene

DNA fragment B consists of _____ base pairs.

1,405

Drag the labels onto the table to indicate whether each patient is likely to have AML, ALL, or neither.

17: ALL 18: neither 19: ALL 20: AML

Assign a numerical score for each category. Then add up the total score. (The highest possible score is 6; the lowest is 0.) In what range does this source fall?

2 to 4

On a scale of 0 to 6, where 6 is the most trustworthy, how would you rate this site? (Note that all responses will be marked as "correct" at this point.)

2-4 (somewhat trustworthy; want to check some things) *Does not matter what you click/personal preferece*

How many DNA molecules would there be after four rounds of PCR if the initial reaction mixture contained two molecules?

32

Which of the following sequences is most likely to be cut by a restriction enzyme?

5-AATATT-3 3-TTATAA-5

In this example the marker DNA includes fragments that have 23,130, 9,416, 6,557, 4,361, 2,322, 2,027, and 564 base pairs. Approximately how many base pairs are in the DNA fragment indicated by the letter A?

6,557

Part D video

A

What is the polymerase chain reaction (PCR)?

A method to amplify a fragment of DNA.

Check each of the true statements about the proteins involved in cutting and pasting DNA. More than one statement may be true. Check all that apply.

A restriction enzyme cuts DNA while DNA ligase pastes DNA. A particular restriction enzyme only cuts DNA at one very specific DNA sequence. DNA ligase pastes together segments of DNA with matching sticky ends.

What is the most favorable characteristic of retroviruses that makes them useful in gene therapy applications?

DNA copies of retroviral genomes become integrated into the genome of the infected cell.

What enzyme forms covalent bonds between restriction fragments?

DNA ligase

Which of these DNA molecules is the shortest?

E

Which of the following statements correctly describes one of the main differences between embryonic stem cells and adult stem cells?

Embryonic stem cells can give rise to all cell types in the organism, and adult stem cells cannot.

True or false? The Taq enzyme is a type of DNA polymerase that allows researchers to separate the DNA strands during the annealing step of the PCR cycle without destroying the polymerase.

False

Which of the following conclusions do the data support? Select all that apply.

For some genes, there is variation in the amount of mRNA present, even among patients in the same group. A different set of genes is transcribed in cells from patients in Group I compared to cells from patients in Group II. If you were given microarray data from the cells of a new patient belonging to either Group I or Group II, you would probably be able to tell which group the patient belongs to.

Which of the following is a concern expressed by opponents of the use of genetically modified (GM) food crops?

GM food crops might pass their new genes to close relatives in nearby wild areas. The protein products of transgenes in GM food crops might lead to allergic reactions in human consumers.

What is the most logical sequence of steps for splicing foreign DNA into a plasmid and inserting the plasmid into a bacterium? I. Transform bacteria with a recombinant DNA molecule. II. Cut the plasmid DNA using restriction enzymes (endonucleases). III. Extract plasmid DNA from bacterial cells. IV. Hydrogen-bond the plasmid DNA to non-plasmid DNA fragments. V. Use ligase to seal plasmid DNA to non-plasmid DNA.

III, II, IV, V, I

Which one of the following statements is correct?

If a restriction enzyme is combined with a piece of DNA that contains its restriction site, the result will be restriction fragments.

Organisms share many conserved core processes and features, including transcription and translation using a uniform genetic code. Scientists have used these shared processes and features in biotechnology. For example, for the process of some transformations, a plasmid is constructed when a eukaryotic gene of interest is added with an antibiotic resistant gene such beta-lactamase, which is used for ampicillin resistance. This plasmid is then inserted into a prokaryotic bacterial cell, such as E-coli, through a transformation process that leads to the production of the product protein from the eukaryotic organism. To culture the bacteria and obtain the protein product, the bacteria must grow. Select the appropriate condition to determine if the plasmid has entered the E-coli bacterial cell.

Nutrient broth to which ampicillin has been added.

What do you find when you click these two links?

One links to another page on the CFS web site, and one links to a paper in a peer-reviewed journal.

Is the information provided by these sites consistent with what you found on the CFS web site?

Other sites discuss both the risks and benefits associated with GMOs.

Part B video

PCR

Drag the labels onto the table to identify which hypothesis is being tested in each comparison and what result you would predict.

Patients with high topoisomerase II expression will respond to etoposide. - patient 1 Patients with low HOXA9 expression will survive better. - Patient 6 Patients with low HOXA9 expression will survive better. - Patient 10

Pax-6 is a gene that is involved in eye formation in many invertebrates, such as Drosophila. Pax-6 is also found in vertebrates. A Pax-6 gene from a mouse can be expressed in a fly and the protein (PAX-6) leads to a compound fly eye. This information suggests which of the following characteristics of this gene?

Pax-6 is highly conserved and shows shared evolutionary ancestry.

A researcher is preparing to insert a human gene of interest into a bacterial plasmid in order to clone the human gene. She has genetically engineered the plasmid to carry a gene amp R , which confers resistance to the antibiotic ampicillin. She will include ampicillin in the plating medium when she grows the recombinant bacteria. Why has she engineered the plasmid to include an antibiotic resistance gene? Choose the best answer.

Recombinant bacteria that have taken up the plasmid can be recognized because they are able to survive in the presence of ampicillin.

What is the affiliation of the writer?

She is on staff at the Center for Food Safety (CFS).

Cold case detectives are investigating a homicide that took place 30 years ago. In reexamining the evidence, they find a tiny spot of blood on the victim's clothing that was likely left by the murderer. The DNA in the blood has partially degraded over time. What technique(s) would the blood lab technicians use in their examination of this tiny, degraded blood sample?

They would use PCR to amplify the DNA.

True or false? Comparison of the sequences of the same gene across species can give some insight into the existence of a common ancestor with that gene.

True

Archaeologists unearthed a human skull with a small dried fragment of the scalp still attached. They extracted a tiny amount of DNA from the scalp tissue. How could they obtain sufficient DNA for an analysis of the ancient human's genes?

Use the polymerase chain reaction.

Select an observation that best describes a correct aspect of the two processes of restriction digest and gel electrophoresis:

When separated on a gel, the pattern of DNA bands will be characteristic of those cut with Hind III, different restriction enzymes will not produce these same fragments.

What information can not be obtained from the sequence of a gene?

Whether the gene is methylated.

During which step in the PCR cycle do primers form bonds with a single-stranded template?

annealing

A principal problem with inserting an unmodified mammalian gene into a plasmid and then getting that gene expressed in bacteria is that _____.

bacteria cannot remove eukaryotic introns

In order to insert a human gene into a plasmid, both must _____

be cut by the same restriction enzyme

In this example the marker DNA includes fragments that have 23,130, 9,416, 6,557, 4,361, 2,322, 2,027, and 564 base pairs. Approximately how many base pairs are in the DNA fragment indicated by the letter B?

between 6,557 and 4,361 base pairs

During which step in the PCR cycle are nucleotides used?

extension

To create a molecule of recombinant DNA, which of the following is cut with a restriction enzyme? Check all that apply.

starting DNA target DNA

Part C video

the DNA will move up the gel

What seems to be the main purpose of the blog post?

to convince the public that genetic engineering is not the solution to citrus greening