Chapter 28 Self-test questions

. What is the natural function of restriction enzymes?

Protecting bacteria by cleaving the DNA of infecting viruses.

Protecting bacteria by cleaving their own DNA.

Protecting bacteria by methylating their own DNA.

Protecting bacteria by methylating the DNA of infecting viruses.

. What is the correct sequence of events in Southern blotting?

Hybridization of DNA fragments with a labelled probe sequence followed by separation by electrophoresis and then transfer to a membrane.

Separation of DNA fragments by electrophoresis followed by hybridization with a labelled probe sequence and then transfer to a membrane.

Separation of DNA fragments by electrophoresis followed by transfer to a membrane and then hybridization with a labelled probe sequence.

Transfer of DNA fragments to a membrane followed by separation by electrophoresis and then hybridization with a labelled probe sequence.

. Dideoxynucleoside triphosphates (ddNTPs) are used in sequencing DNA because:

ddNTPs are fluorescent.

ddNTPs are incorporated very efficiently into DNA by DNA polymerase.

ddNTPs cannot be incorporated into DNA by DNA polymerase.

ddNTPs prevent further DNA synthesis once they are incorporated into the DNA sequence.

. A PCR reaction that continues for 30 cycles will produce approximately how many PCR products from a single template DNA molecule?

64.

128,000.

Approximately 1 million.

Approximately 1 billion.

. Which of the following is NOT required for a PCR reaction?

A thermostable DNA polymerase.

Dideoxy-dNTPs (ddNTPs).

Primers.

Template DNA.

. Plasmid vectors used in cloning often contain a gene for the N-terminal 146 amino acids of the enzyme β-galactosidase. What is the purpose of including this gene in the vector?

It allows selection of E. coli host cells that contain the plasmid.

It allows selection of E. coli host cells that contain plasmid in which the insert has been ligated.

It cleaves the insert to allow it to be ligated into the vector.

It enables the plasmid vector to replicate in E. coli host cells.

. RT-PCR is a method that is used for:

forensic analysis of DNA.

amplification of genomic DNA sequences.

amplification of mRNA sequences.

analysis of mRNA expression.

. Which of the following statements about forensic analysis of DNA is correct?

A DNA profile using short tandem repeats is unique to an individual.

Forensic analysis makes use of SNPs in coding sequences to distinguish between individuals.

PCR is used for DNA profiling (DNA fingerprinting).

DNA fingerprinting cannot be used for paternity testing.

. In the creation of a knockout mouse using homologous recombination, a viral thymidine kinase gene is often included in the vector outside of the region of homology between the vector and targeted chromosome. What is the purpose of this?

To allow negative selection of cells in which integration of the targeting sequence has occurred by homologous recombination.

To allow negative selection of cells in which integration of the targeting sequence has occurred by random insertion into the genome.

To allow positive selection of cells in which integration of the targeting sequence has occurred by homologous recombination.

To allow positive selection of cells in which integration of the targeting sequence has occurred by random insertion into the genome.

. Which of the following methods for introducing DNA into cells is used only for plants?

A gene 'gun'.

Electroporation.

Microinjection.

Transformation of competent cells.

. The first gene therapy clinical trial took place in 1990, on patients with SCID (severe combined immunodeficiency syndrome). True or false?

True.

False.

. Which of the following is true of restriction enzymes? Please select all that apply.

Restriction enzymes are exonucleases.

Restriction enzymes are endonucleases.

Restriction enzymes always cut to leave DNA 'sticky' ends.

Restriction enzymes are part of the defence system of bacteria against attack by bacteriophages.

. Which of the following therapies have been developed using recombinant DNA techniques? Please select all that apply.

Hepatitis B vaccine.

Human insulin for treatment of diabetes.

Human growth hormone.

Tissue plasminogen activator, used for blood clot removal.

. In genome editing using the CRISPR-Cas9 system, what is the function of Cas9?

It is a DNA repair enzyme that introduces mutations into the targeted sequence.

It is an endonuclease that introduces a double-stranded break into the targeted genome sequence.

It is an RNA sequence that guides the CRISPR complex to its target sequence in the genome.

It is the 'donor' sequence that is introduced into the target genome by homologous recombination.

Chapter 28 Self-test questions

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