Biotechnology 4a1y4d

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Biotechnology

Biol 1002 - Spring 2013

Signed in as Nora Trejos

Biotechnology

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Biotechnology Due: 3:00pm on Monday, May 13, 2013 Note: You will receive no credit for late submissions. To learn more, read your instructor's Grading Policy

Restriction Enzymes, Recombinant DNA, and Gene Cloning DNA cloning is a technique for producing many copies of a DNA segment for use in research, medicine, agriculture, or other applications. In this tutorial, you will explore the procedures involved in cloning an imaginary gene in humans. DNA cloning is based on the following sequence of steps: use of restriction enzymes to cut DNA into fragments (Part A) insertion and ligation of DNA fragments into a cloning vector (Part B) transformation and selection of recombinant bacteria (Part C) isolation of desired recombinant bacteria: screening the library (Part D)

Part A - Using restriction enzymes to cut DNA The ability of restriction enzymes to cut DNA at specific sites makes DNA cloning possible. The diagram below shows a section of human DNA that contains an imaginary gene for video game proficiency (the vgp gene), shown in red. Shaded areas mark the restriction sites (also called recognition sites) of four restriction enzymes: EcoRI, HaeIII, BamHI, and HindIII. Arrows indicate where each enzyme cuts the two DNA strands.

Which enzyme(s) will produce a DNA fragment that contains the entire vgp gene (shown in red) and has “sticky ends”? Select all that apply.

Hint 1. The use of restriction enzymes In recombinant DNA technology, restriction enzymes are used to isolate DNA segments (often genes) and recombine them with other pieces of DNA. A restriction enzyme recognizes a specific DNA base sequence—called a restriction site or recognition site—and cuts each strand of the DNA at a particular point within that site. Most restriction sites are symmetrical: On each strand within the site, the sequence of bases is the same when read in the 5' → 3' direction. The restriction site for the enzyme PvuI is an example of a symmetrical site.

Hint 2. What are sticky ends? A restriction enzyme cuts each strand of a DNA molecule at a particular point within the enzyme’s restriction site. If the cuts are staggered —that is, if the cut points on the two strands are not directly opposite each other—the resulting DNA fragments have single-stranded ends. These ends are called “sticky ends” because they can base-pair with complementary single-stranded ends on other DNA fragments. Which of these enzymes produce(s) DNA fragments with sticky ends?

Select all that apply. ANSWER:

session.masteringbiology.com/myct/assignmentPrintView?assignmentID=1937218

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Biotechnology Enzyme X Enzyme Y Enzyme Z

Hint 3. How can scientists produce a DNA fragment that contains a specific gene? To clone a specific gene, scientists start with a much longer stretch of DNA containing the gene and use a restriction enzyme to cut the DNA into many fragments. Only one of these fragments—the one that contains the whole gene—is useful for cloning. This fragment must have two sticky ends to be integrated into a cloning vector, which happens in the next step. To produce a DNA fragment that contains the whole gene and has two sticky ends, where must the enzyme’s restriction sites be located? ANSWER: both inside the gene and outside the gene outside the gene on both sides, but not inside the gene outside the gene on only one side, but not inside the gene inside the gene but not outside the gene

ANSWER: BamHI EcoRI HindIII HaeIII

Correct Cloning the vgp gene requires an enzyme that has restriction sites on both sides of that gene but not within the gene. Two enzymes, HindIII and BamHI, satisfy that requirement, while also producing DNA fragments that have sticky ends. Sticky ends make it possible for the fragments to combine with the DNA of a cloning vector, such as a plasmid.

Part B - Inserting the vgp gene into a cloning vector In the second step of the cloning procedure, DNA fragments produced by a restriction enzyme are inserted into a cloning vector that has been cut by the same enzyme. The vector used in this tutorial is a plasmid. To clone the vgp gene into the plasmid below, a restriction enzyme must do all of the following: cut the human DNA on both sides of the vgp gene, but not inside the gene cut the plasmid without cutting inside the ampicillin resistance gene (ampR ), shown in blue (The importance of the ampR gene will be explained in Part C.) produce sticky ends when it cuts both the human DNA and the plasmid, so that the human DNA fragments can combine with the plasmid


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Biotechnology The questions below will help determine which restriction enzyme should be used to make a plasmid that contains both an intact vgp gene and a functional ampR gene. Answer questions 1–4 by selecting from the answer choices on the left. Drag the correct answer to the right of each question.

Hint 1. How to approach question 1 Find the restriction sites for each enzyme in the human DNA shown in Part A (and repeated here).

An enzyme will cut the human DNA on both sides of the vgp gene only if it has restriction sites to the left and right of the gene. An enzyme will cut inside the vgp gene only if it has a restriction site within the gene. Think about which enzyme(s) satisfy the first condition but not the second.

Hint 2. For question 2, how could a restriction enzyme affect the function of the ampR gene? A gene in a bacterial plasmid consists of a continuous sequence of bases that is transcribed into mRNA, which is translated into a protein. Thus, the function of the gene is to code for a specific protein. In the case of the ampR gene, the gene codes for a protein that enables bacteria to grow in media containing the antibiotic ampicillin. Suppose that a restriction enzyme cut the plasmid within the ampR gene and that an additional piece of DNA were inserted into the gene’s base sequence. How would that affect the mRNA and ultimately the protein encoded by the ampR gene? ANSWER: The mRNA would be abnormal but the protein would be unaffected. The mRNA would be unaffected but the protein would be abnormal. Both the mRNA and the protein would be abnormal.

Hint 3. How to approach question 3 Sticky ends are single-stranded stretches at the ends of a DNA molecule that are formed when restriction enzymes make staggered cuts in DNA. Review the diagrams of the human DNA in Part A and the plasmid in Part B to identify the restriction enzymes that make staggered cuts.

Hint 4. How to approach question 4 An enzyme must satisfy all of these requirements to be useful for creating a recombinant plasmid that contains an intact vgp gene and a functional ampR gene: Requirement 1: The enzyme will produce a human DNA fragment that contains an intact vgp gene. Requirement 2: The enzyme will open up the plasmid but leave the ampR gene intact. Requirement 3: The enzyme will allow the plasmid to incorporate human DNA fragments because sticky ends produced by the same enzyme can base-pair with each other.

ANSWER:


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Correct BamHI cuts the plasmid outside the ampR gene, leaving the gene intact and functional, which is important for the next step in the cloning procedure. Once BamHI opens the plasmid, the sticky ends it produces in the plasmid can base-pair with those on BamHI human DNA fragments. If DNA ligase is then added, it will covalently the sugar-phosphate backbones of the plasmid and the fragments, producing recombinant plasmids.

Note that human DNA contains many BamHI restriction sites in addition to the two shown in Part A. Therefore, only a small fraction of the recombinant plasmids will have the vgp gene, like the plasmid shown above. Most of the recombinant plasmids will have a fragment of human DNA that does not contain the vgp gene, and would not be of interest to the scientists.

Part C - Transformation and selection of recombinant bacteria In the third step of the cloning procedure,all of the plasmids that were created in the second step are incubated with bacteria. The bacteria do not have an ampR gene on their own chromosome. As shown below, at least four classes of bacteria result. Notice that only one class contains the vgp gene

To help sort out those bacteria that have the vgp gene, scientists first attempt to grow the bacteria both in a medium with ampicillin and in a


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Biotechnology medium without ampicillin. Demonstrate your understanding of this step by sorting the four bacterial classes based on where they will grow. Drag the icon for each bacterial class to the appropriate bin.

Hint 1. What is bacterial transformation? Which of the following correctly describes a transformed bacterium? ANSWER: a bacterium that contains both bacterial DNA and human DNA a bacterium that contains a specific human gene a bacterium that has taken up external DNA, such as a plasmid

Hint 2. Using selective media in DNA cloning Most of the bacteria that are incubated with plasmids fail to take up a plasmid. These nontransformed bacteria will not contain the gene to be cloned (vgp, in this hypothetical example), so eliminating them will make later screening for the gene more efficient. If the plasmid includes a gene for resistance to a certain antibiotic, researchers can eliminate nontransformed bacteria by plating all the bacteria on a medium containing that antibiotic.

Hint 3. How do ampicillin-sensitive bacteria become resistant to ampicillin? The third step in the cloning procedure involves incubating ampicillin-sensitive bacteria with plasmids, some of which contain the vgp gene. How do some of these bacteria become resistant to ampicillin? ANSWER: by being transformed by acquiring the vgp gene by mutation

ANSWER:


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Correct Only bacteria that were transformed (picked up a plasmid) can grow in a medium containing ampicillin. Each transformed bacterium reproduces, forming a clone of cells. The complete set of clones is called a plasmid library. Some clones in the library have nonrecombinant plasmids, some have recombinant plasmids without the vgp gene, and a small fraction have recombinant plasmids with the vgp gene.

Part D - Screening the plasmid library The final step of the cloning procedure is to screen the plasmid library for clones that carry the vgp gene, shown in red below. To accomplish the screening, researchers synthesize a single-stranded DNA probe using vgp mRNA as a template. What will be the sequence of nucleotides in the probe? Drag the labels to their appropriate locations in the probe. Labels can be used once, more than once, or not at all.

Hint 1. How to approach this problem The probe is a DNA transcript of the vgp mRNA, which is itself a transcript of the vgp gene’s template strand. In other words, the probe is complementary to the vgp mRNA, which is complementary to the template strand of the gene. To determine the sequence of the DNA probe, follow these steps: 1. Identify which strand is the template strand of the gene (see Hint 2). 2. Transcribe the template strand of the gene into a strand of mRNA. Make sure to mark which end of the mRNA is the 5' end and which is the 3' end. 3. Determine the DNA nucleotide sequence that is complementary to the mRNA strand. Make sure to mark which end of the DNA is the 5' end and which is the 3' end. 4. Enter the sequence of bases in the DNA probe in a 5' → 3' direction from left to right.

Hint 2. How can you identify the template strand of a gene? The template strand is complementary to the mRNA, which begins with the start codon. What is the sequence of the start codon? ANSWER: UGA ATG AUG

Hint 3. How do DNA bases differ from RNA bases? Which bases are found only in DNA, only in RNA, or in both DNA and RNA? ANSWER:


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ANSWER:


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Correct To screen a library of bacterial colonies for clones that carry a specific gene, a relatively short, single-stranded nucleic acid probe is hybridized to the DNA of that gene. Often, the probe is a DNA strand synthesized by reverse transcriptase from the mRNA encoded by the gene.

Bases in the probe hydrogen-bond to complementary bases in the gene. If the probe has been labeled with a radioactive isotope or a fluorescent tag, researchers can identify the bacterial clones that contain the DNA to which the probe has bound. Those clones can be grown in large quantities, allowing many copies of the gene to be isolated for use in research or other applications.

Activity: Cloning a Gene in Bacteria

Click here to complete this activity. Then answer the questions.

Part A In order to insert a human gene into a plasmid, both must _____ ANSWER: have identical DNA sequences originate from the same type of cell code for the same gene product be cut by the same restriction enzyme be the same length

Correct Doing so will result in the formation of complementary sticky ends.

Part B What enzyme forms covalent bonds between restriction fragments? ANSWER:


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Biotechnology DNA primase DNA helicase single-stranded binding protein DNA polymerase DNA ligase

Correct DNA ligase catalyzes the formation of covalent bonds between restriction fragments.

Part C Click on the diagram to start the animation. What name is given to the process shown in this animation?

ANSWER: transduction translation conjugation cloning transformation

Correct Transformation is the process by which a bacterium takes up a plasmid from the surrounding solution.

Part D Click on the diagram to start the animation. What name is given to the process shown in this animation?

ANSWER: transduction translation conjugation cloning transformation

Correct Cloning occurs with the replication of a recombinant plasmid.

Activity: Producing Human Growth Hormone


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Biotechnology

Click here to view this animation. Then answer the questions.

Part A What defect causes pituitary dwarfism?

Hint 1. What is missing in affected individuals? ANSWER: Neurodegeneration Lack of a pituitary gland Lack of growth hormone One defective allele

Correct Affected individuals produce little or no growth hormone.

Part B What is genetic cloning?

Hint 1. What is accomplished when a gene is cloned? ANSWER: A method to find the gene that encodes a certain protein A method to grow a large amount of protein A method to produce many copies of a gene

Correct Genetic cloning is the process by which many identical copies of a gene are produced.

Part C True or false? The use of growth hormone isolated from cadavers was banned mainly because there were not enough cadavers to supply the hormone.

Hint 1. What were the negative effects of using growth hormone isolated from human cadavers?


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Biotechnology ANSWER: True False

Correct The use of growth hormone isolated from cadavers was banned mainly because the isolated hormone was potentially contaminated with prion proteins.

Part D Which of the following statements best describes the function of reverse transcriptase?

Hint 1. The enzyme is used in the construction of cDNA libraries; consider its name to deduce its function. ANSWER: It makes complementary DNA (cDNA) from mRNA. It seals DNA fragments together. It synthesizes double-stranded DNA molecules from single-stranded DNA molecules. It cuts DNA strands at specific sequences.

Correct The function of reverse transcriptase is similar to the reverse of transcription; it makes a single strand of complementary DNA (cDNA) from mRNA.

Part E Which of the following steps would be performed last when screening a cDNA library?

Hint 1. Researchers screen a cDNA library to isolate a specific gene from a collection of DNA sequences. ANSWER: Spread bacterial cells containing the library on a plate to form colonies. Incubate the filters with a gene-specific probe. Treat DNA on the filter to make it single-stranded. Match the region of radioactivity on the filter with the corresponding plate.

Correct This step allows researchers to match the colony on the filter with the colony of the bacterial plate so the correct colony can be grown for further study. It would be the last step in screening a cDNA library.

Part F How can large quantities of protein be produced from a bacterial colony containing the gene of interest?

Hint 1. Think about how a protein can be produced in a microscopic "factory."


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Biotechnology ANSWER: Put a cDNA encoding the protein into a plasmid with a bacterial promoter sequence. Construct a probe that matches part of the gene's sequence. Use reverse transcriptase to make cDNAs. Insert the plasmid containing the cDNA into bacteria.

Correct Once a cDNA is put into a plasmid with a bacterial promoter, the bacteria will transcribe and translate the gene.

Part G True or false? The term "sticky ends" refers to the overhanging ends on DNA that are generated by restriction enzymes, which can base pair with any DNA molecules that contain complementary sticky ends.

Hint 1. The "sticky ends" on both the gene to be cloned and the bacterial plasmid allow the gene to be inserted into the bacterial plasmid. ANSWER: True False

Correct Restriction enzymes cut DNA and generate "sticky ends," which can then base pair with DNA molecules that contain the same sticky ends.

Activity: Restriction Enzymes


Part A The unpaired nucleotides produced by the action of restriction enzymes are referred to as _____. ANSWER: sticky ends base sequences single strands restriction fragments ligases


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Correct They are called sticky ends since they will "stick" to a complementary single-stranded sequence.

Part B The sticky end of the DNA restriction fragment shown here will pair with a DNA restriction fragment with the sticky end _____.

ANSWER: -ACGT -AAAA -ACGU -GTAC -TGCA

Correct The matching of sticky ends follows the rules of specific base pairing.

Activity: Analyzing DNA Fragments Using Gel Electrophoresis


Part A 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?

ANSWER:


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Biotechnology 564 2,027 2,322 6,557 9,416

Correct DNA fragment A moved about the same distance as the third-longest marker DNA fragment.

Part B 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?

ANSWER: between 23,130 and 9,416 base pairs between 9,416 and 6,557 base pairs between 6,557 and 4,361 base pairs between 4,361 and 2,322 base pairs between 2,322 and 2,027 base pairs

Correct DNA fragment B moved farther than the 6,557 base pair marker fragment but not as far as the 4,361 base pair marker fragment.

Part C DNA fragment B consists of _____ base pairs.

ANSWER:


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Biotechnology 564 1,268 1,405 2,027 2,322

Correct Reading the calibration curve should give you a value of 1,405 base pairs for this DNA fragment.

Activity: Gel Electrophoresis of DNA


Part A Click on the diagram to start the animation. This is an animation of gel electrophoresis. Which of these DNA molecules is the shortest?

ANSWER: A B C D E

Correct The shorter the DNA molecule, the farther it moves.

Part B In gel electrophoresis DNA molecules migrate from _____ to _____ ends of the gel. ANSWER:


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Biotechnology acidic ... basic negative ... positive basic ... acidic long ... short positive ... negative

Correct An electrical current is generated across the gel, and DNA molecules migrate from the negative end toward the positive end.

Chapter 20 Pre-Test Question 6 Part A Gel electrophoresis separates DNA fragments on the basis of what characteristic?

Hint 1. Think about how RFLP works. ANSWER: charge length restriction sites mutations sequence

Correct As the DNA fragments move through the gel, longer fragments are impeded more than shorter fragments, producing characteristic banded patterns in the gel.

Chapter 20 Question 14

Part A In order to identify a specific restriction fragment using a probe, what must be done? ANSWER: The fragments must be separated by electrophoresis. The fragments must be treated with heat or chemicals to separate the strands of the double helix. The fragments must be separated by electrophoresis and the fragments must be treated with heat or chemicals to separate the strands of the double helix. The probe must be hybridized with the fragment. The fragments must be separated by electrophoresis, the fragments must be treated with heat or chemicals to separate the strands of the double helix, and the probe must be hybridized with the fragment.

Correct

Chapter 20 Question 15 session.masteringbiology.com/myct/assignmentPrintView?assignmentID=1937218

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Part A DNA microarrays have made a huge impact on genomic studies because they ANSWER: dramatically enhance the efficiency of restriction enzymes. can be used to introduce entire genomes into bacterial cells. can be used to eliminate the function of any gene in the genome. allow the expression of many or even all of the genes in the genome to be compared at once. allow physical maps of the genome to be assembled in a very short time.

Correct


Part A A researcher has used in vitro mutagenesis to mutate a cloned gene and then has reinserted this into a cell. In order to have the mutated sequence disable the function of the gene, what must then occur? ANSWER: replication of the cloned gene using a bacterial plasmid transcription of the cloned gene using a BAC use of a microarray to continued expression of the original gene attachment of the mutated gene to an existing mRNA to be translated recombination resulting in replacement of the wild type with the mutated gene

Correct

Chapter 20 Pre-Test Question 7 Part A If cells from a carrot are removed and placed in a culture medium, they can develop into a normal adult plant. This demonstrates that carrot cells _____.

Hint 1. Consider the cell-level requirements for the development of an adult of any species. ANSWER: are undifferentiated as adult cells differ genetically at maturity differentiate differ as mature cells retain all the genes that were in the zygote that developed into the original plant

Correct Furthermore, the carrot cells are totipotent.


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Chapter 20 Pre-Test Question 8 Part A Which of the following is true of stem cells?

Hint 1. Refer to Figure 20.20 in your textbook. ANSWER: They can reproduce indefinitely in culture. Their use is highly controversial. They can be found in both embryonic and adult tissues. They can differentiate to produce many different kinds of specialized cells. All of the above.

Correct All of these statements are true of stem cells.

Activity: DNA Fingerprinting


Part A This is a DNA fingerprint exhibiting samples from a victim, two suspects, and the crime scene. Which of these DNA fragments is common to both the victim and Suspect 1?

ANSWER: A B C D E


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Correct A visual comparison of the gel electrophoresis results should reveal that Suspect 1 has a DNA fragment that matches victim DNA fragment B.

Part B This is a DNA fingerprint exhibiting samples from a victim, two suspects, and the crime scene. Which of these DNA fragments is common to both the victim and Suspect 2?

ANSWER: A B C D E

Correct A visual comparison of the gel electrophoresis results should reveal that Suspect 2 has a DNA fragment that matches victim DNA fragment C.

Part C Why is Suspect 1 considered more likely to have committed the crime than Suspect 2?

ANSWER: The crime scene sample contains DNA fragments from both the victim and Suspect 1. The crime scene sample contains DNA fragments from both the victim and Suspect 2. Suspect 1 and the victim have more DNA fragments in common that do the victim and Suspect 2. Suspect 2 and the victim have more DNA fragments in common that do the victim and Suspect 1. Suspect 1 and Suspect 2 have more DNA fragments in common than either have in common with the victim.

Correct Such a good match between crime scene DNA fragments and Suspect 1 DNA fragments strongly suggest that Suspect 1 committed the crime.

Activity: Making Decisions About DNA Technology: Golden Rice


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Part A Why is golden rice pale yellow in color? ANSWER: It is rich in chlorophyll a. It is nutrient-poor. It is rich in beta-carotene. It is rich in chlorophyll b. It is rich in phycobilins.

Correct Beta-carotene confers a yellow color on the rice.

Part B Which of these is a symptom of vitamin A deficiency? ANSWER: osteoporosis impaired taste perception overstimulation of the immune system blindness impaired blood clotting

Correct Chronic vitamin A deficiency can lead to blindness.

Part C Which of these is a vitamin A precursor? ANSWER: cobalamin pyridoxine plasmid beta-carotene thiamin


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Correct The body can convert beta-carotene into vitamin A.

Part D The transfer of antibiotic-resistant genes from genetically engineered bacteria to disease-causing bacteria _____. ANSWER: would, if it occurred, be no cause for concern has occurred is likely to occur can never occur seems unlikely

Correct It seems unlikely to occur and there is no evidence that it has occurred.

Video Tutor Session Quiz: DNA Profiling Click the play icon on the Video Tutor Session to your right. You can also the video or view the text of the tutor session to read while you are watching. After you have watched the tutor session, answer the questions. Estimated time: 17 minutes

Part A

ANSWER:


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Biotechnology base double helix polynucleotide phosphate sugar

Correct The phosphate group of a nucleotide, represented here as a yellow ball, contains a negative charge.

Part B

ANSWER:

RFLP analysis PCR DNA fingerprinting gel electrophoresis DNA profiling

Correct This machine is a PCR machine. PCR is a method for amplifying DNA.

Part C

ANSWER:


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Biotechnology the DNA will move in a circle the DNA will move down the gel but twice as fast the DNA will move up the gel it will move down the gel as normal nothing

Correct DNA normally moves down through a gel due to the attraction of opposite charges. In this case, the DNA would move up the gel, toward the positive pole at the top.

Part D

Please use this figure to answer the question posed in the video:

ANSWER:

A B C D E

Correct This gel has one band near the top, which represents a long piece of DNA, and two bands near the bottom, which represent two short pieces of DNA.

Part E Click here to review the figure.


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ANSWER:

the profile from suspect 1 matches the crime scene the profile from suspect 2 matches the crime scene the profiles from suspects 1 and 2 both match the crime scene neither profile matches the crime scene you cannot conclude anything

Correct Notice that the locations of the bands in the right column, which is suspect 2, match the locations of bands in the first column from the crime scene. But the bands in the middle column do not match. Thus, we can conclude that the DNA profile from the crime scene matches the DNA profile from suspect 2.

ABC News Video: Genetically Altered Salmon Watch the ABC News video (2:21 minutes). Then answer the questions below.

Part A For the first time, the U.S. Food and Drug istration is considering whether to allow the sale of _____. ANSWER:


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Biotechnology endangered species of plants food from a genetically altered animal fungi as food seaweed as a drug

Correct

Part B The fish in the video have been genetically engineered to _____. ANSWER: produce pink meat reproduce later in life grow faster resist bacterial infections

Correct

Part C The modified salmon were created by _____. ANSWER: adding genetic material from a Pacific salmon and an eel-like fish producing only male salmon, which tend to be larger than females fusing salmon and shark eggs injecting the salmon with steroids, such as testosterone

Correct

Part D According to the producers of the genetically modified salmon, the meat _____. ANSWER: tastes like chicken looks and tastes the same as unmodified salmon has a distinctly different color from unmodified salmon has a distinctly different taste from unmodified salmon

Correct

Part E What concerns do some consumer groups have about genetically modified fish? ANSWER:


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Biotechnology They want to prevent genetically modified fish from breeding with wild fish. They want more studies on the health effects that genetically modified fish may have on people who eat it. They want food from genetically modified fish to be clearly labeled as genetically modified. all of the above

Correct

Part F How does the company raising these fish claim to prevent the genetically modified fish from breeding with wild fish? ANSWER: The genetically modified fish are sterile. Fish are raised in individual isolation and are unable to interact with each other. The fish are killed before they are old enough to reproduce. Escaped fish are caught and removed from the ocean.

Correct

Current Events: From Ancient Giants, Finding New Life to Help the Planet (New York Times, 4/9/2011) Read this New York Times article and then answer the questions. From Ancient Giants, Finding New Life to Help the Planet (New York Times, 4/9/2011) Registration with The New York Times provides instant access to breaking news on NYTimes.com. To , go to http://www.nytimes.com/. Visit http://www.nytimes.com/content/help/rights//-of-service.html to review the current NYT of Service.

Part A Ultimately, the Archangel Ancient Tree Archive hopes their work will slow climate change, because the trees they produce will do what? ANSWER: take in carbon dioxide take in oxygen release carbon dioxide release oxygen

Correct

Part B The Archangel Ancient Tree Archive focuses on getting what from the trees? ANSWER: DNA RNA ATP amino acids

Correct

Part C session.masteringbiology.com/myct/assignmentPrintView?assignmentID=1937218

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Biotechnology Which two trees are the current focus of the Archangel Ancient Tree Archive? ANSWER: sequoia and oak redwood and maple redwood and oak redwood and sequoia

Correct

Part D You discover a new species of tree that has pollen and eggs. What do you know about this species? ANSWER: It reproduces by spores. It reproduces asexually. It is unable to reproduce. It reproduces sexually.

Correct

Part E What caused the demise of nearly all of the native redwoods in the United States? ANSWER: insect pests logging fire disease

Correct

Misconception Question 96

Part A

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. ANSWER:


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Biotechnology Recombinant bacteria that have taken up the plasmid can be recognized because the antibiotic resistance gene produces a blue color. Recombinant bacteria that have taken up the plasmid can be recognized because they are able to survive in the presence of ampicillin. Recombinant bacteria that have taken up the plasmid are vulnerable to infection and require antibiotic resistance.

Correct Read about cloning a eukaryotic gene in a bacterial plasmid.


Part A

The researcher also inserts another gene into the plasmid. The lacZ gene encodes the enzyme ß-galactosidase, which catalyzes a synthetic molecule called X-gal to form a blue product. X-gal is included in the plating medium. The restriction enzyme used by the researcher cleaves a recognition sequence within the lacZ gene. Why did the researcher insert the lacZ gene into the plasmid? ANSWER: Recombinant bacteria cannot produce the blue product. Recombinant bacteria will be blue. The lacZ gene will allow the recombinant bacteria to use X-gal as a food source.

Correct Read about cloning a eukaryotic gene in a bacterial plasmid.


Part A The vertebrate Pax-6 gene product (the PAX-6 protein) triggers a complex program of gene expression resulting in formation of the vertebrate eye, which has a single lens. The fly Pax-6 gene leads to formation of the compound fly eye. When scientists cloned a mouse Pax-6 gene and introduced it into a fly embryo, it led to formation of the compound eye of a fly. What did scientists induce from this? ANSWER: Flies and mice have a more recent common ancestor than we originally thought. All genes controlling eye development are identical in flies and mice. The Pax-6 genes of flies and mice arose from an ancestral gene in a common ancestor.

Correct Read about cross-species gene expression.


Part A 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


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Biotechnology 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? Select all that apply. ANSWER: They would use PCR to amplify the DNA. They would use reverse transcriptase-polymerase chain reaction (RT-PCR) to determine the genes expressed in this DNA. They would use a restriction enzyme and DNA ligase to make recombinant DNA from this sample.

Correct PCR is impressive in the speed and specificity with which it amplifies DNA. Only minute amounts of DNA need be present in the starting material, and this DNA can be in a partially degraded state, as long as a few molecules contain the complete target sequence. Read about the polymerase chain reaction.


Part A Which of the following is a concern expressed by opponents of the use of genetically modified (GM) food crops? Select all that apply. ANSWER: GM food crops might their new genes to human consumers. The protein products of transgenes in GM food crops might lead to allergic reactions in human consumers. GM food crops might their new genes to close relatives in nearby wild areas.

Correct Read about the safety and ethical questions raised by DNA technology.


Part A RNAi methodology uses double-stranded pieces of RNA to trigger breakdown of a specific mRNA or inhibition of its translation. For which of the following might this technique be useful? ANSWER: o raise the concentration of a desired protein to raise the rate of production of a needed digestive enzyme to destroy an unwanted allele in a homozygous individual to decrease the production from a harmful mutated gene to form a knockout organism that will not the deleted sequence to its progeny

Correct


Part A session.masteringbiology.com/myct/assignmentPrintView?assignmentID=1937218

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Biotechnology Which of the following uses reverse transcriptase to make cDNA followed by amplification? ANSWER: Southern blotting Northern blotting RT-PCR Eastern blotting Western blotting

Correct


Part A In 1997, Dolly the sheep was cloned. Which of the following processes was used? ANSWER: isolation of stem cells from a lamb embryo and production of a zygote equivalent separation of an early stage sheep blastula into separate cells, one of which was incubated in a surrogate ewe replication and dedifferentiation of adult stem cells from sheep bone marrow use of mitochondrial DNA from adult female cells of another ewe fusion of an adult cell's nucleus with an enucleated sheep egg, followed by incubation in a surrogate

Correct


Part A Which of the following problems with animal cloning might result in premature death of the clones? ANSWER: abnormal gene regulation due to variant methylation use of pluripotent instead of totipotent stem cells abnormal immune function due to bone marrow dysfunction the indefinite replication of totipotent stem cells use of nuclear DNA as well as mtDNA

Correct Score Summary: Your score on this assignment is 83.6%. You received 21.74 out of a possible total of 26 points.


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