Recombinant DNA Technology Quiz

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Questions and Answers

What is the primary function of recombinant DNA technology in research?

Studying the structure and function of genes in various organisms. (correct)

Improving the efficiency of food production.

Creating new types of microorganisms.

Developing new methods for bacterial cell growth.

What specific biological technique is used to visualize DNA molecules based on their size?

Microscopy.

Spectrophotometry.

Agarose gel electrophoresis. (correct)

Centrifugation.

What are the two main types of pipettes mentioned in the context of this practical?

Automatic and glass. (correct)

Automatic and manual.

Glass and plastic.

Micropipettes and macropipettes.

What is the primary benefit of separating plasmid DNA from bacterial cells?

To study the structure and function of the plasmid DNA itself. Signup and view all the answers

What is the significance of the bacterium Escherichia coli (E. coli) in the development of recombinant DNA technology?

It is a model organism commonly used for genetic manipulation. Signup and view all the answers

What are the two primary applications of recombinant DNA technology mentioned in the context?

Gene identification and protein production. Signup and view all the answers

Which of the following is NOT a transferable research skill mentioned in the context?

DNA sequencing. Signup and view all the answers

What is the primary purpose of the online practical described in the text?

To teach students how to purify plasmid DNA from bacterial cells. Signup and view all the answers

What is the purpose of the glycerol in the loading buffer?

To increase the density of the DNA sample, ensuring it sinks into the well. Signup and view all the answers

What is the purpose of the bromophenol blue in the loading buffer?

To provide a visual marker for the progress of electrophoresis. Signup and view all the answers

What is the purpose of the DNA markers (M) in the gel?

To serve as a reference for the size of the extracted plasmid DNA. Signup and view all the answers

Why is it important to remove all ethanol from the DNA sample before resuspending it in TE buffer?

Ethanol can prevent the DNA from dissolving in the TE buffer, hindering further analysis. Signup and view all the answers

What is the main purpose of using an agarose gel in this experiment?

To visualize and separate DNA fragments based on their size. Signup and view all the answers

What is the function of the TE buffer?

To dissolve the DNA sample and provide a suitable environment for its storage. Signup and view all the answers

Why is a positive control (previously purified pBluescript DNA) used in this experiment?

To validate the DNA extraction process and ensure that the extracted DNA is of sufficient quality. Signup and view all the answers

Why should gloves be worn when handling gels containing SafeView or SafeStain?

To avoid skin irritation caused by the stain. Signup and view all the answers

What is the typical behavior of supercoiled plasmid DNA during gel electrophoresis?

It runs faster than linear plasmid DNA. Signup and view all the answers

What is the result of RNA contamination in plasmid DNA preparations?

RNA appears as a bright smear or cloud in the gel. Signup and view all the answers

In the presence of chromosomal DNA, where would this DNA appear on the gel compared to the 10 kbp marker fragment?

It would run higher than the 10 kbp marker. Signup and view all the answers

Which form of plasmid is expected to be present in plasmid mini-preps?

Both supercoiled and relaxed circular plasmid DNA. Signup and view all the answers

If chromosomal DNA is present during plasmid DNA preparation, what effect may this have?

It may cause difficulty in distinguishing plasmid bands on the gel. Signup and view all the answers

What is the primary purpose of agarose gel electrophoresis in relation to DNA fragments?

To estimate the size of DNA fragments Signup and view all the answers

Which of the following types of plasmid DNA migrates the fastest through an agarose gel?

Supercoiled plasmid DNA Signup and view all the answers

Which statement describes relaxed or 'nicked' plasmid DNA?

It has one strand nicked, resulting in a larger size for gel movement. Signup and view all the answers

What happens to plasmid DNA when both strands are cut at the same place?

It converts to a linear form and has an intermediate migration rate. Signup and view all the answers

Which factor does NOT affect plasmid DNA migration through an agarose gel?

Presence of RNA in the sample Signup and view all the answers

How does the molecular conformation of plasmid DNA influence its migration in gel electrophoresis?

Different conformations lead to varying speeds in migration. Signup and view all the answers

What is the result of torsional stress being released in supercoiled plasmid DNA?

It becomes relaxed and develops into a slower migrating form. Signup and view all the answers

In addition to plasmid DNA, which other types of genetic material might be observed on agarose gels?

Contaminating chromosomal DNA and RNA Signup and view all the answers

What is the primary characteristic of plasmids?

They replicate alongside the bacterial chromosome. Signup and view all the answers

Which strain of E.coli is typically used in laboratories for research and teaching?

K12 strain Signup and view all the answers

What advantage do plasmids provide to bacterial cells?

They allow for horizontal gene transmission. Signup and view all the answers

Which of the following best describes a plasmid with a high copy number?

It can accumulate hundreds of copies in a single cell. Signup and view all the answers

What is the purpose of a plasmid mini-prep?

To isolate plasmid DNA from bacterial cells. Signup and view all the answers

Which of the following is NOT a function of plasmids?

Inducing mutations in the bacterial genome. Signup and view all the answers

What are pBluescript and pGLO used for in laboratory settings?

As cloning vectors for DNA manipulation. Signup and view all the answers

Which statement correctly describes the size range of plasmids?

Plasmids can range from approximately 1000 base-pairs to several thousand kilobase-pairs. Signup and view all the answers

What is the primary purpose of adding glucose in Solution 1?

To increase osmotic pressure Signup and view all the answers

What role does EDTA play in Solution 1?

Inhibits DNases by binding ions Signup and view all the answers

What occurs after adding Solution 2 to the pellet in the tube?

Cells undergo lysis Signup and view all the answers

What component is present in Solution 2 that aids in the rupture of cells?

Sodium hydroxide Signup and view all the answers

Why is it important to keep the tubes inverted for mixing after adding Solutions 1 and 2?

To ensure even distribution of reagents Signup and view all the answers

What is the expected outcome after adding Solution 3 to the mix?

Visible white precipitate formation Signup and view all the answers

Which of the following best describes the action of acetic acid in Solution 3?

It neutralizes the pH to facilitate renaturation of DNA Signup and view all the answers

What characteristic is observed after the cellular debris precipitates in Solution 3?

Presence of SDS and protein precipitate Signup and view all the answers

Study Notes

Plasmid DNA Purification

Plasmid DNA is extra-chromosomal, circular DNA found in bacteria.
It's not essential for bacterial survival but often contains beneficial genes (e.g., antibiotic resistance).
Plasmids replicate independently of the bacterial chromosome (low or high copy number).
Plasmids are used in many laboratory procedures, like DNA cloning.

Online Practical 5

Students will isolate plasmid DNA from E. coli bacteria.
Methods to visualize plasmid DNA will be used.
This process includes separating DNA molecules based on size (agarose gel electrophoresis).
Essential microcentrifugation, pipetting techniques to isolate plasmid DNA are skills to be learned.

Agarose Gel Electrophoresis

Separates nucleic acids (DNA, RNA) based on size.
Agarose gel acts as a molecular sieve (matrix of holes).
Smaller fragments move faster than larger ones.
DNA is negatively charged, moving towards the positive electrode.
SafeView dye (binds to DNA/RNA) makes fragments visible under UV light.
DNA size estimation and quantification are possible.

Plasmid DNA Conformations

Plasmid DNA in bacteria is often supercoiled (coiled tightly).
Relaxed or 'nicked' form results from a strand break in the DNA molecule.
Linear DNA, cut, moves slower than supercoiled in the agarose gel.

Experimental Procedure

Overnight E. coli cultures are the starting material.
Cells are harvested, lysed (broken open).
Cellular debris is removed to isolate the plasmid DNA.
DNA is precipitated.
Ethanol washes are used to purify the DNA.
The clean plasmid DNA is resuspended in TE buffer.
Results (plasmid conformations, size estimations) are analyzed.

Gel Analysis

The results from the gel are visualized.
Chromosomal DNA, that has been degraded and is small, might also appear.
RNA is present in the original E. coli, running independently.
Markers (DNA fragments of known size) help interpret unknown sizes.

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Description

Test your knowledge on recombinant DNA technology and its applications in research. This quiz covers essential techniques, the significance of E. coli, and practical skills related to DNA visualization and pipetting. Perfect for biology students looking to deepen their understanding of genetic engineering.