Chat with us, powered by LiveChat Why is E. coli so widely used as a host organism - Uni Pal

Why is E. coli so widely used as a host organism in which to clone genes?

A. It is closely related to human genes

  • B. Many different E. coli strains with distinct and useful properties are available
  • C. E. coli has the ability to post translationally modify genes
  • D. E. coli was the first gene discovered

Type II restriction endonucleases are useful in recombinant DNA research primarily because

A. The will digest any nucleic acid

  • B. they cut both strands of DNA at a specific recognition site
  • C. they can distinguish between genomic and cDNA.
  • D. they cleave DNA at a distance from the recognition site

Reverse transcriptase synthesizes

A. DNA from an RNA template

  • B. cDNA from the RNA template
  • C. cDNA from the mRNA template
  • D. RNA from the DNA template

You are analyzing the tissue-specific expression of a poorly characterized gene in mice. Which type of gene would serve as the best positive control for your experiment?

A. another poorly characterized or unknown gene

  • B. a known gene that exhibits constitutive expression
  • C. a known gene that exhibits spatial expression
  • D. a known gene that exhibits temporal expression

A coimmunoprecipitation assay is a process that is used to identify

A. protein structure

  • B. protein-protein interactions
  • C. transcriptional activity
  • D. DNA-protein interactions

You are interested in an uncharacterized gene that contains an interesting combination of predicted protein domains. To determine in which mouse tissues it is expressed, the best method is

A. Northern blot

  • B. transient transfection assay
  • C. coimmunoprecipitation
  • D. DNase I footprinting

In recombinant DNA technology, the term competency refers to

A. the ability of DNA ends to be ligated

  • B. the ability of cells to take up foreign DNA
  • C. the ability of an enzyme to be activated by ATP
  • D. the ability of a medium to select for transformed cells

To analyze the results of a DNA sequencing reaction, which type of gel should you prepare?

A. agarose gel

  • B. pulsed field gel
  • C. nondenaturing polyacrylamide gel
  • D. denaturing polyacrylamide gel

Production of recombinant proteins in bacteria involves the cloning of the cDNA encoding the desired protein into an “expression vector” that contains a(n)

A. start codon

  • B. enhancer
  • C. promoter
  • D. intron

Reverse transcriptase synthesizes A. DNA from an RNA template

  • B. DNA from DNA template
  • C. RNA from a DNA template
  • D. RNA from an RNA template

Which of the following enzymes is involved in the PCR process?

A. DNA primase

  • B. DNA polymerase
  • C. DNA helicase
  • D. DNA ligase

Which step in Southern blotting allows an investigator to identify a particular DNA fragment that is present within a complex mixture of fragments?

  • A. hybridization with a labeled probe
  • B. agarose gel electrophoresis
  • C. blotting
  • D. restriction endonuclease digestion of DNA

When performing gel electrophoresis, why do molecular biologists add a “ladder” made up of nucleic acids or proteins of known size?

  • A. To help macromolecules move through the gel more rapidly.
  • B. The macromolecules being studied would be invisible without the ladder.
  • C. To help determine the size of each macromolecule after the separation has occurred.
  • D. To make sure the dye included in the sample buffer doesn’t interfere with the movement of the macromolecules that are being studied.

Double-stranded RNAs are processed by the enzyme _______ to form small interfering RNAs (siRNAs). One strand of the siRNA is loaded into a silencing complex named _________. The siRNAs target mRNA for ___________ .

  • A. Dicer, RISC, splicing
  • B. Dicer, RISC, degradation
  • C. RISC, Dicer, degradation
  • D. RISC, Dicer, spicing

You have screened a library by nucleic acid hybridization with a probe for a particular gene sequence. In the final phase of library screening, you apply an X-ray film to the membrane. The resulting autoradiogram has two black spots corresponding to two separate bacterial colonies. Which of the following explanations is the most likely?

A. The library screening was a failure because there should be blue and white colonies on the autoradiogram.

  • B. The temperature at which the high stringency washes was performed was too high.
  • C. The gene is large and fragmented between two different clones.
  • D. One of the spots must be an artifact because only one bacterial colony should contain the gene of interest.

Northern blotting is the process that is used to identify

A. DNA-protein interactions

  • B. RNA
  • C. DNA
  • D. proteins

Automated DNA sequencing differs from manual DNA sequence in which way?

  • A. ddNTPs are not used in automated DNA sequencing.
  • B. Automated DNA sequencing uses radioactive markers.
  • C. Instead of having to run four separate sequencing reactions, in automated sequencing the reactions can be combined into one tube.
  • D. In automated DNA sequencing, DNA fragments are separated by sequence instead of by size.

You are testing protein X and protein Y in a yeast two-hybrid assay that uses lacZ as a reporter gene. Production of a blue product signifies that:

A. protein X interacts with protein Y

  • B. protein X produced protein Y
  • C. protein X does not interact with protein Y
  • D. protein Y produced protein X

The polymerase chain reaction does not require

A. DNA polymerase

  • B. primers
  • C. DNA ligase
  • D. dNTPs

It is common to use ddNTPs (dideoxynucleoside triphosphates) for sequencing DNA because, when incorporated into a growing DNA polymer, the ddNTP acts as a chain terminator, allowing the researcher an opportunity to determine the last-added base to a given chain. From your knowledge of nucleotide structure and DNA synthesis, what is the most likely attribute of ddNTPs for DNA sequencing?

  • A. The ddNTPs lack a nitrogenous base.
  • B. The ddNTPs lack a 3? hydroxyl group.
  • C. The ddNTPs lack the sugar component.
  • D. The ddNTPs lack a 5? carbon.
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