DNA Technology

Answer: B. Excised DNA would be the original sequence. The cDNA also codes for the protein, but does not contain introns like the unprocessed excised sequence. Gel electrophoresis separates fragments based on size, with smaller fragments traveling further. The intron-less cDNA would travel further than the excised and unprocessed DNA.

A researcher has identified the location of the gene that codes for protein X, and has managed to excise it from the DNA. She has also generated cDNA that codes for the protein. If she runs these two sequences through gel electrophoresis, what should she expect to see? (Note that the wells where the DNA was loaded onto the gel are at the top of the gels shown)

Answer: B. Antibiotics kill bacteria - they are not part of the transfection process. Adding antibiotics is a vital step that allows scientists to selectively grow only the bacteria that carry the antibiotic-resistant gene that was transfected into them. Bacteria divide very rapidly. By the time the scientist came in to check on his petri dish, it would have been covered in a lawn of transformed and untransformed bacteria.

A scientist is trying to express gene X in bacteria. After cloning the cDNA from gene X into a plasmid with the appropriate cDNA, and transfecting the plasmid into bacteria the scientist notices that he forgot to add antibiotics. What will greet him the next day? A. A petri dish with separate colonies of transformed and untransformed bacteria B. A petri dish completely overrun with untransformed and transformed bacteria C. A mostly normal petri dish - antibiotics are just used as a safeguard against other bacteria D.A petri dish with only untransformed bacteria, the antibiotics are required for transfection

Answer: B. Taq polymerase is a heat-sensitive polymerase originally found in hot springs. Southern blot, gel electrophoresis, and microarray assays are all methods that require large amounts of DNA to work effectively. Taq polymerase, nucleotides, and primer are enzymes and substrates used to make DNA, so the student is most like preparing to run a PCR.

A student adds Taq Polymerase, nucleotides, and primer to a test tube. What procedure are they most likely going to do next? A. Southern blot B. Polymerase chain reaction C. Microarray hybridization assay D. Gel electrophoresis

Answer: D. DNA polymerase builds DNA using a DNA template. RNA polymerase builds RNA using a DNA template. The student most likely forgot to add reverse transcriptase, leaving the experiment stranded as mRNA.

A student was attempting to make cDNA that would code for protein Y. They began with an isolated and amplified sample of the target post-transcriptional mRNA, and all the tools required to complete the task. However, at the end of the experiment the student was left with a molecule containing ribonucleotides. What most likely went wrong? A. The student added RNA polymerase instead of DNA polymerase B. The cloning vector already transcribed the DNA C. The student forgot to add DNA polymerase D. The student forgot to add reverse transcriptase

1. Cloned gene is microinjected into the nucleus of the fertilized ovum 2. The gene incorporates the DNA into the zygote 3. Ovum is implanted into surrogate mother

Describe the process of introducing a transgene into a fertilized ovum.

-Genetically modifying plants to be resistant to herbicides or insects -Genetically modifying plants to delay the ripening of crops, which allows the crops to last longer.

What are some applications of DNA technology in the field of agriculture?

It terminates the elongation of DNA strands generated in PCR, which results in varying sizes of DNA strands, which they can be read in order in gel electrophoresis to identify the DNA sequence of that strand.

What is the purpose of radio-labeled dideoxyribonucleotides in DNA sequencing?

1. Cloned gene is injected into embryonic stem cells 2. Altered stem cells are injected into the developing blastocyst 3. Blastocyst is implanted into surrogate mother

Describe the process of introducing a transgene into an embryonic stem cell line.

cDNA libraries. Genomic libraries may contain the entire genome of an organism, but genes may be split into multiple vectors since genes in this library contains introns as well as exons. Since cDNA does not contain any introns, the genes will not be split into multiple vectors in order to be effective.

Of the two types of DNA libraries, which one is more commonly used to reliably sequence specific genes and identify disease-causing mutations? Explain why.

-Replicate a certain gene of interest to further research the effects of that gene -Mass producing the product of that gene for research or for sale.

What are some applications of DNA cloning?

-Making transgenic animals -Cloning animals

What are some applications of DNA technology for animal husbandry?

-Genetically modifiying pests to make them infertile -Genetically modify bacteria to degrade waste faster

What are some applications of DNA technology for environmental protection?

Answer: B. One of the primary ethical concerns related to gene sequencing is the issue of consent and privacy. Because genetic screening provides information on direct relatives, there are potential violations of privacy in communicating this information to family members who may be at risk. There are not significant physical risks, eliminating (A), and gene sequencing is fairly accurate, eliminating (C) and (D).

Which of the following is an ethical concern of gene sequencing? A. Gene sequencing is invasive, thus the potential health risks must be thoroughly explained B. Gene sequencing impacts relatives, thus privacy concerns may be raised C. Gene sequencing is very inaccurate, which increases anxiety related to findings D. Gene sequencing can provide false-negative results, giving a false sense of security

Answer: C. Sanger sequencing uses ddNTPs (dideoxy nucleoside triphosphates) which end chain-progression in order to create a lot of aborted sequences. Smaller fragments travel further towards the positive edge in gel electrophoresis. The sequence of the amplified DNA (note that this is not the template strand!) is 5' ACTGTCAGT 3', which is found by reading the sequence from bottom → up. The question though asked us for the "Template" strand, which will be the reverse compliment of the amplified DNA. Thus by taking the revese compliment of the amplified sequence, we get 5' ACTGACAGT 3'

A DNA sample was sent off for Sanger sequencing. The results are shown below. What is the sequence of the template strand? A. 5' TGACAGTCA 3' B. 5' TGACTGTCA 3' C. 5' ACTGACAGT 3' D. 5' ACTGTCAGT 3'

Answer: A. The complementary strand to the one given must start with 3' GTT ... 5'. A palindromic sequence of DNA will read the same sequence 5' → 3' on either strand. Remember, a palindromic sequence of DNA is slightly different than a palindromic number, such as "12321," or word such as "stats." In order for it to be palindromic, the final part of the sequence recognized by BamHI is 5' TTG 3'.

BamHI recognizes 6 base pairs of DNA in a palindromic DNA sequence. If the first part of the sequence is given below, what is the rest of it? 5' C A A ? ? ? 3' A. 5' TTG 3' B. 5' CAA 3' C. 5' AAC 3' D. 5' GTT 3'

1. Genomic: Chromosomal DNA cDNA: mRNA reverse transcription 2. Genomic: Restriction endonuclease, DNA ligase cDNA: Reverse transcriptase, DNA ligase 3. Genomic: Yes cDNA: No 4. Genomic: Not all the time, sometimes the gene is split into multiple vectors cDNA: Yes 5. Genomic: Yes cDNA: No 6. Genomic: Yes, but they are not always on the same vector cDNA: No 7. Genomic: No cDNA: Yes 8. Genomic: No cDNA: Yes

Compare and contrast genomic libraries and cDNA expression libraries for the following: 1. Where is DNA obtained for each library? 2. What are the enzymes that are used to expand those libraries? 3. Do they contain non-expressed sequences of chromosomes? 4. Are the cloned genes complete sequences? 5. Do the cloned genes contain introns? 6. Are the promoter and enhancer sequences present for these libraries? 7. Can the genes be expressed in their host? 8. Can the gene be used for gene therapy or constructing transgenic animals?

1. The wells in the microarray chip are treated with complimentary mRNA strands of a particular gene. 2. The mRNAs of the particular gene is extracted from two different cells, and are radio-labeled to differentiate where they originated from. 3. The mRNA of both cells are inserted into the wells and are observed by which colored radio-label is more prominent to determine the transcriptional activity of the gene of one cell compared to another.

Describe how a microarray is carried out.

1. Use restriction endonucleases to excise the gene of interest from the DNA strand. The excised gene will have sticky ends as a result of the restriction endonucleases. 2. The sticky ends of the gene is paired with the sticky ends of the plasmids with the base pairs complimentary to the ends of the gene. 3. DNA ligase connects the backbone of the gene with the backbone of the plasmid. 4. Insert the antibiotic resistance gene into the plasmid. 5. DNA ligase connects the backbone of the antibiotic resistance gene with the backbone of the plasmid. 6. Plasmid is inserted into bacteria by giving a heat shock to the system, which makes the bacteria uptake the plasmid. 7. Bacteria culture is placed onto a petri dish that contains nutrients that promotes bacterial growth and an antibiotic (usually penicillin). 8. Bacteria that took up the plasmid will survive while bacteria without the plasmid dies out, leaving us with a culture of bacteria that contains the plasmid. 9. Bacteria keeps replicating the gene and also expresses the gene in the plasmid to produce the product of the gene.

Describe the process of DNA cloning.

1. Take a strand of DNA that you want to sequence and perform a PCR on it to amplify the sample. 2. In the PCR reaction, fluorescently labeled dideoxyribonucleotides will bind to elongating chains, which will terminate elongation. This leads to DNA strands of varying length being produced and being terminated at different points. 3. Run the synthesized strands of DNA through gel electrophoresis, which causes the fragments to be separated by size. 4. A computer can analyze the fluorescently labeled dideoxyribonucleotides, which allows the fluorescent labels to be read in order. The order the fluorescent labels allows us to determine the sequence of that particular DNA sequence.

Describe the process of DNA sequencing.

1. Take the strand of DNA and cleave it into smaller pieces using restriction enzymes. 2. Run the fragments through gel electrophoresis, which allows us to separate the DNA fragments based on size difference. 3. DNA is denatured in the gel by making the pH of the buffer basic by using urea. 4. DNA fragments are carefully transferred to a membrane filter, which retains the separation of the fragments. 5. A radio-labeled single-stranded DNA probe is introduced to the filter, which will bind to its complimentary sequence and form a double-stranded DNA. 6. Filter is exposed to an x-ray film that allows us to visualize where the radio-labeled probe annealed to, which will identify whether or not that gene is present in the DNA strand.

Describe the process of Southern Blotting.

Dideoxyribonucleotides lacks the 3' -OH group that is required for DNA strand elongation. Thus, once a dideoxyribonucleotide is added to a growing DNA molecule, no more nucleotides can be added because dideoxyribonucleotides have no 3' -OH groups that can form a phosphodiester bond with.

During DNA sequencing, why does the DNA polymer stop growing once a dideoxyribonucleotide is added?

Usually through vectors, most often modified viruses that are unable to complete their replication cycle. The genome of the modified virus is altered where a great portion of the genome is replaced with the cloned gene, which allows the virus to infect the mutated cells, but not complete its replication cycle.

How are genes usually transferred to affected cells in gene therapy?

The synthesized DNA strands have radio-labeled dideoxyribonucleotides, which show up in gel electrophoresis. The order that the dideoxyribonucleotides appear in the gel shows the sequence of DNA.

How are you able to determine the sequence of a DNA strand in DNA sequencing?

-Microinjecting the cloned gene into the nucleus of a fertilized ovum -Microinjecting the cloned gene into the nucleus of an embryonic stem cell line

How can a transgene be introduced into an organism?

Before inserting them in a well, fragments are usually labeled with some sort of marker that is added. Markers are usually fluorescent, which allows us to locate the DNA fragment when exposed to UV light. A good example of a marker is the intercalator known as ethidium bromide (EtBr).

How do we determine where a DNA fragment is located in an agarose gel?

DNA fragments are inserted into the wells of an agarose gel resting in a buffer solution. An electric field is generated in the buffer by an electrolytic cell, where the fragments of DNA migrate from the cathode to the anode through the gel. The DNA fragments that travel further in the gel are smaller, while the fragments that do not migrate far in the gel are larger. The further the fragment travels through the gel, the smaller the DNA fragment is.

How does gel electrophoresis work?

Answer: B. cDNA is formed from a processed mRNA strand by reverse transcription. cDNA is used in DNA libraries and contains only the exons of genes that are transcriptionally active in the sample tissue.

How is cDNA best characterized? A. cDNA results from a DNA transcript with noncoding regions removed B. cDNA results from the reverse transcription of processed mRNA C. cDNA is the abbreviation for deoxycytosine D. cDNA is the circular DNA molecule that forms the bacterial genome.

By reverse transcribing mRNA with the use of reverse transcriptase.

How is cDNA generated?

Number of base pairs

How is the length of a DNA fragment measured in electrophoresis?

It indicates more than one fragment of DNA, and of different lengths.

If one well exhibits multiple bands in the gel, what does that indicate?

Anode is positively charged Cathode is negatively charged

In electrophoresis, what is the charge of the anode and cathode of the electrolytic cell generating the electric field?

To keep the pH of the gel from deviating as the electric field is emitted across the gel. If the pH of the gel deviates too far, it could alter the charge of the DNA fragments.

In electrophoresis, what is the purpose of the buffer solution?

Answer: A. Restriction enzymes destroy unprotected DNA, which is usually foreign. Hosts can protect their DNA by methylation. Viruses do not have restriction enzymes. Restriction enzymes are found in bacteria as a defense against invading viruses.

In nature, restriction enzymes are meant to protect: A. Bacteria from viruses B. Bacteria from other bacteria C. Viruses from bacteria D. Humans from bacteria

Answer: A. During PCR, DNA segments are separated such that the polymerase can build complementary strands. In an ideal experiment, each DNA segment is separated and replicated during each round. After 3 rounds of PCR there should be 8 DNA segments, with the original segment split.

PCR (polymerase chain reaction) is an excellent method of generating copies of target DNA. If a single piece of double stranded DNA (dsDNA) is put into a PCR machine, how many dsDNA segments will there be after 3 rounds? A. 8 segments, with the 2 original strands on different segments B. 16 segments, with the 2 original strands on different segments C. 8 segments, with the 2 original strands paired D. 16 segments, with the 2 original strands paired

Answer: A. Plasmids are circular pieces of DNA, so one cut will make one fragment, two cuts will make two fragments, etc. When EcoRI and BamHI are used together, the 14kb fragment created by BamHI alone is preserved. This implies that both EcoRI sites are within the same BamHI-bound fragment. When HindIII and EcoRI are used together, a 5kb fragment is preserved. The only way the restriction enzymes produce the fragment sizes listed in the table is if two EcoRI sites are bounded by two BamHI sites, while a HindIII site is opposite them:

Plasmid G is cut with the restriction enzymes EcoRi, BamHI, and HindIII in various combinations. The sizes of the resulting fragments are seen below. BamHI 14 kb 20 kb BamHI + EcoRI 3 kb 5 kb 12 kb 14 kb EcoRI + HindIII 5 kb 13 kb 16 kb BamHI + EcoRI + HindIII 3 kb 4 kb 5 kb 10 kb 12 kb Which of the displayed plasmids is an accurate representation of plasmid G?

Answer: D. Endonucleases are enzymes that cut DNA. They are used by the cell for DNA repair. They are also used by scientists during DNA analysis, as restriction enzymes are endonucleases. Restriction enzymes are used to cleave DNA before electrophoresis and Southern blotting, and to introduce a gene of interest into a viral vector for gene therapy.

Restriction endonucleases are used for which of the following? I. Gene therapy II. Southern blotting III. DNA repair A. I only B. II only C. II and III only D. I, II, and III

The wells in the microarray chip will exhibit a fluorescent yellow color, since the oncogene is more expressed than the proto-oncogene, thus the mutated skin cell will produce more mRNA than the normal skin cell, meaning that the gene expression in the oncogene is greater than that of the proto-oncogene.

Say for a microarray analysis, that the oncogene of a mutated skin cell is compared to the proto-oncogene of a normal skin cell. If the mRNA for the oncogene was radiolabeled with a fluorescent yellow and the mRNA for the proto-oncogene was radiolabeled with a fluorescent blue, what would most likely be the outcome of the microarray analysis?

The wells in the microarray chip will exhibit a fluorescent blue color, since the normal tumor supressor gene is more transcriptionally active than the mutated tumor supressor gene. Thus, the normal skin cell will have greater gene expression than the mutated skin cell.

Say for a microarray analysis, that the tumor supressor gene of a mutated skin cell is compared to the tumor supressor gene of a normal skin cell. If the mRNA for the mutated tumor supressor was radiolabeled with a fluorescent yellow and the mRNA for the normal tumor supressor was radiolabeled blue, what would be the most likely outcome of the microarray analysis?

-Utilizing noncoding regions of the genome to identify a potential suspect at a crime scene -Identifying an individual with the use of short tandem repeats (STRs), mitochondrial DNA, and Y-chromosome typing (Y-STRs).

What are some applications of DNA technology in the field of forensics?

-Synthesis of insulin and human growth hormone through DNA cloning. -Development of vaccines by recreating the capsid of a virus -Synthesis of other hormones and proteins -Personalized chemotherapeutic regimens in cancer by genotyping the tumor cell

What are some applications of DNA technology in the field of medicine?

-Do we have the right to alter someone's genes? -Do we have the right to control the genetic complement of the human population and other eugenic considerations? -Is it right to genetically modify an infant? -Any risks to the privacy of an individual? -Can genetic information be used in a discriminatory manner?

What are some ethical concerns of using DNA technology?

-Unintended result of the formation of a pathogen that is resistant to available cures -Injection of genetically modified cells may result in the harm of the health of the individual -Protection of researchers working on the recombinant DNA technology

What are some safety concerns of using DNA biotechnology?

Single stranded ends of DNA left after cutting with restriction endonucleases. They are formed when restriction endonucleases cleaves a palindromic sequence on a DNA strand. They are easier to integrate into genomic material than DNA fragments without sticky ends.

What are sticky ends? How are they produced? What is their purpose?

-Allows the investigation of minute samples of DNA -Forensics: drop of blood, cells of a hair follicle -Detection of genetic defects in embryos -Analysis of mitochondrial DNA

What are the applications of PCR?

1. Gene of particular interest 2. Restriction endonucleases 3. Plasmid 4. Antibiotic resistance gene 5. Bacteria 6. Nutrients for bacterial growth 7. DNA ligase

What are the components that are needed to perform DNA cloning?

1. Nucleotides 2. RNA primers 3. Taq polymerase 4. Strand of DNA we are interested in

What are the components that are used do perform a PCR?

1. Nucleotides 2. RNA primers 3. DNA polymerase 4. DNA strand of interest 5. Dideoxyribonucleotides

What are the components used for DNA sequencing?

1. An origin of replication 2. A sequence that is recognized by the restriction endonucleases 3. A gene for antibiotic resistance 4. Gene of interest

What are the essential components for a vector in DNA cloning?

1. Add all the components of the PCR into a solution 2. Heat up the solution to denature the double helix of DNA into two separate strands (usually around 96°C) 3. Cool the solution to allow the RNA primers to anneal to the two DNA strands (usually around 55°C) 4. Heat the solution up a little more to allow the taq polymerase to synthesize a complimentary DNA strand from the location of the RNA primer using the nucleotides that we added in the solution (usually around 72°C) 5. Cycle is repeated multiple times, which creates a chain reaction that allows the amount of double-stranded DNA to be doubled after each cycle.

What are the steps in a polymerase chain reaction (PCR)?

1. Genomic DNA libraries 2. cDNA/expressive libraries Expressive libraries gives DNA sequences without any introns, while genomic libraries contains DNA sequences with introns.

What are the two types of DNA libraries, and how do they differ?

DNA-DNA hybridization DNA-RNA hybridization

What are the two types of hybridization?

A dideoxyribonucleotide has a hydrogen at its 3' carbon, whereas a deoxyribonucleotide has a hydroxyl group at its 3' carbon.

What differentiates a dideoxyribonucleotide from a deoxyribonucleotide?

PCR increases the number of copies of a given DNA sequence and can be used for a sample containing very few copies of the DNA sequence. Southern blotting is useful when searching for a particular DNA sequence because it separates the DNA fragments by length and then probes for a sequence of interest.

What does PCR accomplish for a researcher? What about Southern Blotting?

Separates them by size and charge.

What does gel eletrophoresis separate macromolecules by?

It involves the insertion of working copies of a gene into the cells of a person with a genetic disorder in an attempt to correct the disorder

What does gene therapy usually involve?

It is similar to Southern Blotting. It is a research technique that is used to determine if a specific RNA molecule is present in a sample of RNA. It involves using a radio-labeled DNA probe to bind to its complimentary RNA sequence in the sample.

What is Northern Blotting?

A database that can give the DNA sequence for any protein.

What is a DNA library?

An offspring who have patches of cells that are from two different lineages.

What is a chimera?

It is a sequence of double-stranded DNA where both strands have the same sequence in the 5'--->3' direction. Ex: 5'-CAATTG-3' 3'-GTTAAC-5'

What is a palindromic sequence of DNA?

A gene that has been extracted from the DNA of one organism and transferred into the DNA of an organism of another species.

What is a transgene?

Southern Blotting Northern Blotting

What is an example of DNA-DNA hybridization? What is an example of DNA-RNA hybridization?

Transgenic mice are formed by introducing a cloned gene into a fertilized ova or into embryonic stem cells. Knock-out mice are formed by intentionally deleting (knocking out) a gene in the genome of the mice. Transgenic mice can be used to study the effects of dominant alleles. Knock-out mice can help us identify the function of a specific gene by deleting the gene and determine which function is missing due to it.

What is the difference between a transgenic mice and a knock-out mice? What is the benefit of these two types of mice in DNA technology?

cDNA do not contain any introns, while genomic DNA does.

What is the difference between genomic DNA and cDNA?

Offspring will contain the transgene in all of its cells, including germ cells. Because of this, the offspring will pass the transgene off to its own offspring.

What is the outcome of introducing a transgene into a fertilized ovum?

The blastocyst will consist of two types of stem cells: the original ones and the ones containing the transgene. The resulting offspring will be a chimera, where patches of cells (including germ cells) are derived from two different lineages.

What is the outcome of introducing a transgene into an embryonic stem cell line?

It is used as a reference in gel electrophoresis to determine the length of a DNA fragment.

What is the purpose of a DNA ladder?

To determine if a specific piece of DNA is present in a strand of DNA.

What is the purpose of a Southern Blot test?

-Assess the gene transcription profiles of a mutated gene compared to a normal gene -Identify and devise treatments for a disease based on the genetic profile of the disease (drug therapies).

What is the purpose of a microarray?

It allows us to synthesize many copies of a particular gene or fragment of DNA that we are interested in, and isolate it.

What is the purpose of a polymerase chain reaction (PCR)?

To determine the length of a fragment of DNA, RNA, or protein.

What is the purpose of gel electrophoresis?

It will anneal (bind) to the single-stranded DNA sequence that is complimentary to the probe, which will let us identify whether or not that gene is present in the DNA sequence.

What is the purpose of the radio-labeled probe DNA in Southern Blotting?

At palindromic sequences.

What type of DNA sequences do restriction endonucleases cleave at?

They originated from bacteria. The purpose of restriction endonucleases in bacteria is to protect bacteria from viral infections by excising any viral DNA that has integrated into the genetic material of the bacteria.

What type of organism do restriction endonucleases originate from? What was the function of restriction endonucleases in those organisms?

Genomic libraries include all of the DNA in an organism's genome, including noncoding regions. This may be useful for studying DNA in introns, centromeres, or telomeres. cDNA libraries only include expressed genes from a given tissue, but can be used to express recombinant proteins or to perform gene therapy.

When creating a DNA library, what are some of the advantages of genomic libraries? What about cDNA libraries?

Answer: A. The polymerase chain reaction is used to clone a sequence of DNA using a DNA sample, a primer, free nucleotides, and enzymes. The polymerase from Thermus aquaticus (Taq polymerase) is used because the reaction is regulated by thermal cycling, which would denature human enzymes.

Which of the following statements regarding polymerase chain reaction is false? A. Human DNA polymerase is used because it is the most accurate B. A primer must be prepared with a complimentary sequence to part of the DNA of interest C. Repeated heating and cooling cycles allow the enzymes to act specifically and replaces helicase. D. Each cycle of the polymerase chain reaction doubles the amount of DNA of interest

Answer: D. Polymerase Chain Reaction uses specially constructed primers to amplify a specific DNA sequence. Thus, you can tell if the target sequence was in the sample based on if the reaction produces more nucleic acid. A Southern blot is one of the most efficient method for detecting the presence of a specific DNA sequence in a sample. It works via hybridization of the target sequence to a probe. If the probe latches on, the target is there. Gel Electrophoresis separates fragments based on size, and so is not nearly as specific as the other techniques mentioned above.

Which procedure is least effective for detecting a specific DNA sequence in a sample? A. Southern blot B. Polymerase chain reaction C. Microarray D. Gel electrophoresis

-Microarray -Southern blotting -PCR -Northern blotting

Which types of DNA biotechnology is hybridization used in?

Longer fragments will face more resistance from the agarose molecules in the gel than the smaller fragments, meaning that longer fragments will have an easier time migrating through the gel.

Why do shorter fragments of DNA migrate further than longer fragments of DNA?

To make it more likely for a primer to bind to DNA than for the two strands of DNA to bind to each other again at lower temperatures.

Why do we add a lot of primers in a PCR solution?

In a neutral pH, DNA is negatively charged. Furthermore, the power source used in electrophoresis is an electrolytic cell. Unlike a galvanic cell, the cathode and anode are negatively and positively charged in an electrolytic cell, respectively. So, the negative charge of the DNA will migrate towards the positive charge of the anode.

Why does DNA migrate towards the anode in gel electrophoresis?

Human DNA polymerase denatures at temperatures higher than 37°C (body temperature), meaning that it will not be able to synthesize a complimentary strand at high temperatures. Taq polymerase is fairly heat resistant, meaning that it is able to synthesize complimentary strands of DNA at higher temperatures.

Why is taq polymerase used in a PCR instead of human DNA polymerase?

Recombinant DNA

__________________________ is DNA that is produced by combining DNA from different sources