Nucleic Acid Analysis and Techniques
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Questions and Answers

What role do restriction endonucleases play in DNA analysis?

  • They synthesize new DNA sequences.
  • They amplify DNA fragments for testing.
  • They catalyze cleavage of DNA at selective sites. (correct)
  • They repair broken DNA strands.

What indicates the presence of a restriction site in alleles?

  • The size of the DNA fragment after digestion.
  • Absence of alleles in homologous chromosomes.
  • The number of chromosomes in the genome.
  • Single nucleotide polymorphisms (SNPs). (correct)

What observable outcome occurs when genomic DNA is treated with a restriction enzyme?

  • The DNA becomes fully linearized without fragments.
  • A large smear of DNA is observed in the gel. (correct)
  • A clear band pattern is visible in agarose gel.
  • Distinct, identifiable bands appear on the gel.

What is the purpose of transferring agarose gels to a membrane in RFLP analysis?

<p>To facilitate hybridization with DNA probes. (A)</p> Signup and view all the answers

What does hybridization with a radioactive probe reveal in RFLP analysis?

<p>Specific complementary sequences through distinct bands. (D)</p> Signup and view all the answers

What are oligonucleotide primers primarily used for in molecular biology?

<p>To initiate DNA synthesis (A)</p> Signup and view all the answers

Which component is crucial for DNA denaturation and renaturation during the polymerization process?

<p>Buffer system (A)</p> Signup and view all the answers

What is the purpose of restriction endonucleases in molecular cloning?

<p>To cleave DNA strands for recombination (C)</p> Signup and view all the answers

Which of the following best describes the role of plasmids in molecular cloning?

<p>They are self-replicating DNA molecules that contain protective genes (B)</p> Signup and view all the answers

What is the minimum length of the origin of replication (Ori) in plasmids?

<p>50 - 100 base pairs (B)</p> Signup and view all the answers

What type of DNA is synthesized from a single stranded RNA template?

<p>Complementary DNA (D)</p> Signup and view all the answers

Which of the following is NOT a function of the buffer system in DNA replication?

<p>Suppressing gene expression (D)</p> Signup and view all the answers

Which process is responsible for the synthesis of mRNA from a gene?

<p>Transcription (B)</p> Signup and view all the answers

Bacteriophage DNA is particularly useful for cloning which size of DNA fragments?

<p>13,000 to 23,000 base pairs (B)</p> Signup and view all the answers

The selectable gene in cloning vectors primarily serves what purpose?

<p>To encode antibiotic resistance for screening (A)</p> Signup and view all the answers

What important modifications are made to mRNA after transcription?

<p>Addition of the 5′-CAP and Poly-A Tail (B)</p> Signup and view all the answers

What is a primary application of the Polymerase Chain Reaction (PCR)?

<p>To amplify specific sequences of DNA (D)</p> Signup and view all the answers

What is the primary function of ribosomes in the cell?

<p>Translate mRNA into protein (D)</p> Signup and view all the answers

Which enzyme is commonly used in PCR to synthesize DNA?

<p>Taq polymerase (B)</p> Signup and view all the answers

Which type of DNA is the main component of chromosomes in eukaryotic cells?

<p>Genomic DNA (C)</p> Signup and view all the answers

What is the purpose of ddNTPs in the Sanger chain termination method?

<p>To terminate DNA replication (D)</p> Signup and view all the answers

What is the first step in DNA isolation from cells?

<p>Collect cells (C)</p> Signup and view all the answers

Which of the following is NOT a step in the Sanger sequencing method?

<p>Hydrolysis of RNA (C)</p> Signup and view all the answers

Which enzyme catalyzes the reaction to synthesize complementary DNA from RNA?

<p>Reverse transcriptase (B)</p> Signup and view all the answers

What does biotechnology primarily rely on?

<p>The alteration of genetic characteristics of organisms (D)</p> Signup and view all the answers

What technique uses ice-cold ethanol to precipitate DNA?

<p>Ethanol precipitation (C)</p> Signup and view all the answers

What is the role of sodium acetate in DNA purification?

<p>Increase ionic strength (A)</p> Signup and view all the answers

Which method is primarily associated with the application of gene replacement techniques?

<p>Gene therapy (C)</p> Signup and view all the answers

Which of the following best describes the difference between genomic DNA and complementary DNA?

<p>Genomic DNA contains introns while cDNA does not (D)</p> Signup and view all the answers

What type of biological material can be produced through the methods described in biotechnology?

<p>Food, fuels, and proteins (C)</p> Signup and view all the answers

Which of the following describes the Maxam-Gilbert method of DNA sequencing?

<p>Relies on chemical cleavage of specific bases (D)</p> Signup and view all the answers

What is one of the applications of using bacteria and plants in biotechnology?

<p>Cleaning up chemical wastes (B)</p> Signup and view all the answers

Which of the following is a method for identifying biological specimens at crime scenes?

<p>DNA fingerprinting (A)</p> Signup and view all the answers

What is the primary function of the ampicillin-resistance gene (ampr)?

<p>It encodes β-lactamase to inactivate ampicillin. (B)</p> Signup and view all the answers

Which enzyme is responsible for the generation of complementary DNA (cDNA) from an RNA template?

<p>Reverse transcriptase (B)</p> Signup and view all the answers

What role do restriction endonucleases play in DNA manipulation?

<p>They cleave DNA at specific sites. (A)</p> Signup and view all the answers

What is the blue product formed during blue-white screening?

<p>5,5'-dibromo-4,4'-dichloro-indigo. (D)</p> Signup and view all the answers

What happens during the transformation process involving CaCl2?

<p>It promotes binding of plasmid DNA to lipopolysaccharides. (C)</p> Signup and view all the answers

What method is used to permanently join foreign DNA to the vector?

<p>Ligation (B)</p> Signup and view all the answers

What is the role of β-lactamase in bacterial transformation?

<p>Inactivates specific antibiotics. (B)</p> Signup and view all the answers

What is the significance of using X-gal in the blue-white screening process?

<p>It serves as a substrate for beta-galactosidase. (A)</p> Signup and view all the answers

What is the temperature combination used during heat shock in transformation?

<p>4 degrees Celsius and 42 degrees Celsius (C)</p> Signup and view all the answers

Which component is necessary for selection of successful transformants?

<p>A selectable gene (A)</p> Signup and view all the answers

Flashcards

Restriction Enzymes

Enzymes that cut DNA at specific sequences. Think of them like molecular scissors that precisely snip DNA strands.

RFLP Analysis

A technique that uses restriction enzymes to identify variations in DNA sequences. These variations can be unique to individuals.

Probe DNA

A short piece of DNA that's radioactive. It binds to complementary DNA sequences on a membrane, revealing their location.

Agarose Gel

A gel used to separate DNA fragments based on their size. Smaller fragments travel faster through the gel.

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Single Nucleotide Polymorphisms (SNPs)

Variations in a single DNA nucleotide between individuals. These variations can create or destroy restriction enzyme sites.

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Thermostable DNA Polymerase

A DNA polymerase that can withstand very high temperatures without denaturing, allowing for the amplification of DNA in PCR.

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Oligonucleotide Primers

Short, single-stranded DNA sequences that are complementary to the 3' ends of the DNA strands being amplified, providing a starting point for DNA polymerase.

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Deoxyribonucleotide Triphosphates (dNTPs)

The building blocks for DNA synthesis, providing the energy and the individual bases needed for chain elongation.

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Buffer System in Molecular Cloning

A solution that maintains the optimal pH and ionic strength for DNA polymerase activity, DNA denaturation, and renaturation.

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Vectors in Molecular Cloning

DNA molecules that carry foreign DNA into a host cell, allowing for amplification and expression of the inserted gene.

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Restriction Endonucleases

Enzymes that cut DNA at specific sequences, allowing for the insertion of foreign DNA into a vector.

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Ligation

The joining of two DNA fragments, specifically the insertion of a foreign DNA fragment into a vector.

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Transformation (Molecular Cloning)

The process of introducing recombinant DNA into a host cell, allowing for the replication and expression of the inserted gene.

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Ampicillin-Resistance Gene (ampr)

A gene that encodes β-lactamase, an enzyme that inactivates the antibiotic ampicillin.

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β-Lactamase

An enzyme that breaks down the β-lactam ring in antibiotics like ampicillin, rendering them ineffective.

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lacZ Gene

Part of the lac operon, this gene encodes β-galactosidase, an enzyme that breaks down lactose.

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Blue-White Screening

A technique used to identify bacteria that have successfully taken up a foreign DNA fragment.

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X-gal

A substrate for β-galactosidase, producing a blue color when broken down.

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Reverse Transcriptase (RT)

An enzyme used to generate complementary DNA (cDNA) from an RNA template.

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Transformation

The process of introducing foreign DNA into host cells.

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Selectable Gene

A gene that confers resistance to a specific antibiotic, allowing for the selection of transformed cells.

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What are the two types of DNA?

Genomic DNA (gDNA) and complementary DNA (cDNA).

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What is genomic DNA (gDNA)?

Chromosomal DNA found in most cells of an organism.

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What is complementary DNA (cDNA)?

DNA synthesized from a single-stranded RNA template using reverse transcriptase.

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How is DNA purified?

DNA can be isolated by cell lysis, followed by treating with concentrated salt solution to precipitate proteins, lipids and RNA, followed by centrifugation, then finally ethanol precipitation or phenol-chloroform extraction.

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What is cell lysis?

Breaking open cells to release their contents.

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What is the purpose of using concentrated salt solution in DNA purification?

To precipitate proteins, lipids and RNA, forming a clump that can be separated from the DNA solution by centrifugation.

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What is ethanol precipitation?

A technique used to separate DNA from a solution by adding ice-cold ethanol or isopropanol, causing the DNA to aggregate and form a pellet upon centrifugation.

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What is the role of phenol-chloroform in DNA purification?

Phenol denatures proteins, separating them from the DNA. After centrifugation, denatured proteins remain in the organic phase (phenol-chloroform), while DNA stays in the aqueous phase.

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What is silica spin column purification?

A technique that uses a silica membrane to bind DNA, allowing unwanted components to be washed away.

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Why is DNA purification important?

Purification allows for the analysis of DNA, such as sequencing, PCR, and cloning.

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Biotechnology

The use of living organisms, cells, or their components to solve problems or develop practical applications.

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Examples of Biotechnology

Biotechnology has various applications, including food production (cheese, wine), disease treatment (producing proteins), industrial production (enzymes), genetic modification of plants, fuel production, waste cleanup, metal extraction, gene therapy, crime scene identification, and animal production.

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DNA Sequencing

The process of determining the exact order of nucleotides (A, T, C, G) in a DNA molecule.

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Maxam-Gilbert Method

A DNA sequencing method involving chemical modification of bases, cleavage at specific bases, and analysis by electrophoresis and autoradiography.

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Sanger Chain Termination Method

A DNA sequencing method using ddNTPs to terminate DNA replication, creating fragments of varying lengths that are then analyzed by electrophoresis and autoradiography.

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Polymerase Chain Reaction (PCR)

A technique for amplifying specific DNA sequences from a small sample by using heat-stable DNA polymerase.

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PCR Components

A typical PCR reaction mixture consists of DNA template, DNA polymerase (Taq polymerase), primers, dNTPs, and buffer.

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Taq Polymerase

A heat-stable DNA polymerase used in PCR that can withstand high temperatures required for DNA denaturation during the process.

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Applications of PCR

PCR is widely used in various fields, including diagnostics (detecting diseases), forensics (DNA profiling), research (studying gene expression), and genetic engineering.

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How does PCR amplify DNA?

PCR involves three steps: denaturation (separating DNA strands), annealing (primers attaching to template), and elongation (DNA polymerase extending primers). These steps are repeated to make many copies.

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Study Notes

Nucleic Acid Analysis

  • DNA can be isolated from living, dead, and extinct species.
  • Two types of DNA exist: genomic DNA (gDNA) and complementary DNA (cDNA).
  • Genomic DNA is chromosomal DNA, and most organisms have the same gDNA in every cell.
  • Complementary DNA is synthesized from single-stranded RNA, catalyzed by reverse transcriptase.

DNA Isolation Techniques

  • Friedrich Miescher first isolated DNA in 1869.
  • Purification kits are commercially available.
  • Isolation methods include: collecting cells, cell lysis (using detergents, surfactants, and enzymes like RNase), treatment with concentrated salt solution to clump unwanted molecules, centrifugation to separate DNA from other material.

Gel Electrophoresis

  • DNA solutions, except for high concentrations, are colorless and visually similar to water.
  • Gel electrophoresis is a method to separate DNA molecules, utilizing an electric field through agarose gel to separate DNA fragments.

DNA Fingerprinting

  • A technique used to identify DNA patterns.
  • No two organisms have identical DNA sequences.
  • Used in crime scene investigations, and to identify individuals with particular genetic conditions.

Restriction Fragment Length Polymorphism (RFLP)

  • DNA from different sources will have variations or polymorphisms.
  • Restriction enzymes are used to tease out these differences.
  • RFLP analysis requires a probe to a specific area of DNA to be used to identify specific locations, then transferred to membranes, hybridized to radioactive probes.

Restriction Endonucleases

  • Enzymes that cleave DNA at specific sites.
  • Varying cleavage patterns (e.g., 5' overhang or blunt ends).
  • Examples of enzymes and source organisms are provided (e.g., EcoRI from Escherichia coli, PstI from Providencia stuartii, SmaI from Serratia marcescens).

RFLP Alleles

  • Individuals have pairs of homologous chromosomes with the same loci, but may contain different alleles (variations at those loci).
  • RFLP markers and inheritance patterns are relevant.

Biotechnology

  • Application of organisms, biological cells, and components to practical problems.
  • Examples include food commodity production, increased production of scarce proteins for medicines, industrial chemical production, modifying plant genes for adverse conditions, biofuel production, biowaste cleanup, and gene therapy.

DNA Sequencing

  • Maxam-Gilbert method—a chemical method for DNA sequencing.
  • Sanger chain termination method—a DNA sequencing method using dideoxynucleotides to terminate DNA synthesis and separate DNA fragments by electrophoresis.

Polymerase Chain Reaction (PCR)

  • Method to amplify specific DNA sequences.
  • Conceived by Kary Mullis in 1983.
  • Uses heat-stable DNA polymerase, template DNA, primers, and nucleotides.
  • Steps include denaturation, annealing, and extension.

Recombinant DNA Technology

  • Covalent insertion of a DNA fragment from one type of cell into another.
  • Produces multiple copies of the gene and protein in the host cell

Cloning Vectors

  • Plasmids are self-replicating extrachromosomal DNA molecules found in bacterial cells.
  • Bacteriophages are viral DNA used to infect host cells; useful for cloning larger DNA fragments.
  • pUC18 is an example of a cloning plasmid.

### Ori-Origin of Replication

  • DNA sequences (50-100 base pairs) present in a plasmid, which host cell enzymes bind to initiate replication. 

LacZ

  • Part of the lac operon, encoding beta-galactosidase.
  • Useful for screening transformed cells (blue-white screening).
  • X-gal is a substrate for beta-galactosidase. 

Preparation of Foreign DNA

  • Chemical synthesis—chemical synthesis of DNA base by base.
  • Reverse transcription—mRNA is transcribed into DNA using reverse transcriptase.  
  • Restriction endonuclease action—cleaving larger DNA fragments at specific sites.

Transformation

  • Introduction of foreign DNA into host cells (e.g., E. coli).
  • Using CaCl2 to increase the permeability of the host cells to take up the foreign DNA.
  • Heat shock is used to promote DNA uptake. 

Selection

  • Identify successfully transformed cells using antibiotic resistance.
  • Selectable genes are used (e.g., ampicillin resistance gene or ampR).
  • β-lactamase is an example of an enzyme coded by selectable genes.

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Description

Explore the fascinating world of nucleic acids through techniques like DNA isolation, gel electrophoresis, and DNA fingerprinting. This quiz covers key concepts such as genomic DNA, complementary DNA, and historical milestones in DNA analysis. Test your knowledge on the methods used to study and manipulate DNA.

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