5 Written questions
5 Matching questions
- A eukaryotic gene has "sticky ends" produced by the restriction endonucleaseEcoRI. The gene is added to a mixture containingEcoRI and a bacterial plasmid that carries two genes conferring resistance to ampicillin and tetracycline. The plasmid has one recognition site for EcoRI located in the tetracycline resistance gene. This mixture is incubated for several hours, exposed to DNA ligase, and then added to bacteria growing in nutrient broth. The bacteria are allowed to grow overnight and are streaked on a plate using a technique that produces isolated colonies that are clones of the original. Samples of these colonies are then grown in four different media: nutrient broth plus ampicillin, nutrient broth plus tetracycline, nutrient broth plus ampicillin and tetracycline, and nutrient broth without antibiotics.
Bacteria that do not take up any plasmids would grow on which media?
A) the nutrient broth and the tetracycline broth
B) all three broths
C) the tetracycline broth and the ampicillin broth
D) the nutrient broth and the ampicillin broth
E) the nutrient broth only
- One successful form of gene therapy has involved delivery of an allele for the enzyme adenosine deaminase (ADA) to bone marrow cells of a child with SCID, and delivery of these engineered cells back to the bone marrow of the affected child. What is one major reason for the success of this procedure as opposed to many other efforts at gene therapy?
A) The engineered bone marrow cells from this patient can be used for any other SCID patient.
B) No vector is required to introduce the allele into ADA-negative cells.
C) The engineered cells, when reintroduced into the patient, find their way back to the bone
D) The ADA-introduced allele causes all other ADA-negative cells to die.
E) The immune system fails to recognize cells with the variant gene.
- A researcher needs to clone a sequence of part of a eukaryotic genome in order to express the sequence and to modify the polypeptide product. She would be able to satisfy these requirements by using which of the following vectors?
A) a human chromosome
B) a bacterial plasmid
C) a YAC with appropriate cellular enzymes
D) BAC to accommodate the size of the sequence
E) a modified bacteriophage
- Which of the following best describes siRNA?
A) a molecule, known as Dicer, that can degrade other mRNA sequences
B) a short double-stranded RNA, one of whose strands can complement and inactivate a sequence of mRNA
C) a portion of rRNA that allows it to bind to several ribosomal proteins in forming large or small subunits
D) a single-stranded RNA that can, where it has internal complementary base pairs, fold into cloverleaf patterns
E) a double-stranded RNA that is formed by cleavage of hairpin loops in a larger precursor
- A researcher found a method she could use to manipulate and quantify phosphorylation and methylation in embryonic cells in culture. In one set of experiments she succeeded in decreasing methylation of histone tails. Which of the following results would she most likely see?
A) inactivation of the selected genes B) increased chromatin condensation
C) abnormalities of mouse embryos D) decreased chromatin condensation
E) decreased binding of transcription factors
- a B) a short double-stranded RNA, one of whose strands can complement and inactivate a sequence of mRNA
- b B) increased chromatin condensation
- c C) The engineered cells, when reintroduced into the patient, find their way back to the bone marrow
- d E) the nutrient broth only
- e C) a YAC with appropriate cellular enzymes
5 Multiple choice questions
- C) The RNA is only translated into a single long polypeptide, which is then cleaved into shorter ones
- A) to attach the DNA fragments to a permanent substrate
- D) copies of the herpes virus genome permanently maintained in host nuclei
- C) it uses viral RNA as a template for DNA synthesis
- D) continuous transcription of the operon's genes
5 True/False questions
Which of the following can be effective in preventing the onset of viral infection in humans?
A) applying antiseptics
B) getting vaccinated
C) taking nucleoside analogs that inhibit transcription
D) taking vitamins
E) taking antibiotics → B) Transferred genes may not have appropriately controlled activity
In order to identify a specific restriction fragment using a probe, what must be done?
A) The fragments must be separated by electrophoresis.
B) The fragments must be separated by electrophoresis, the fragments must be treated with heat or chemicals to separate the strands of the double helix, and the probe must be hybridized with the fragment.
C) The fragments must be treated with heat or chemicals to separate the strands of the double helix.
D) The probe must be hybridized with the fragment.
E) The fragments must be separated by electrophoresis and the fragments must be treated
with heat or chemicals to separate the strands of the double helix. → D) single nucleotide polymorphisms found only in persons with a particular disorder
For a repressible operon to be transcribed, which of the following must occur?
A) RNA polymerase must not occupy the promoter, and the repressor must be inactive.
B) RNA polymerase must bind to the promoter, and the repressor must be inactive.
C) RNA polymerase and the active repressor must be present.
D) A corepressor must be present.
E) RNA polymerase cannot be present, and the repressor must be inactive. → B) RNA polymerase must bind to the promoter, and the repressor must be inactive
Gene expression might be altered at the level of post-transcriptional processing in eukaryotes rather than prokaryotes because of which of the following?
A) Eukaryotic exons may be spliced in alternative patterns.
B) Prokaryotic genes are expressed as mRNA, which is more stable in the cell.
C) Eukaryotic mRNAs get 5' caps and 3' tails.
D) Prokaryotes use ribosomes of different structure and size.
E) Eukaryotic coded polypeptides often require cleaving of signal sequences before localization. → C) the removal of introns and alternative splicing of exons
Which of the following sequences in double-stranded DNA is most likely to be recognized as a cutting site for a restriction enzyme?
TTTT → E) it is an activator for other genes