5 Written Questions

1. D) the germ cells of the adult
2. C) The RNA is only translated into a single long polypeptide, which is then cleaved into shorter ones
3. E) retroviruses
4. C) decrease in glucose and increase in cAMP
5. D) single nucleotide polymorphisms found only in persons with a particular disorder

5 Matching Questions

1. The product of the bicoid gene in Drosophila provides essential information about
   A) the left-right axis.
   B) the dorsal-ventral axis.
   C) segmentation.
   D) the anterior-posterior axis.
   E) lethal genes.
2. If you were to observe the activity of methylated DNA, you would expect it to
   A) have turned off or slowed down the process of transcription.
   B) induce protein synthesis by not allowing repressors to bind to it.
   C) be unwinding in preparation for protein synthesis.
   D) be very actively transcribed and translated.
   E) be replicating nearly continuously.
3. 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.
4. CML (chronic myelogenous leukemia) results from a translocation between human chromosomes 9 and 22. The resulting chromosome 22 is significantly shorter than usual, and it is known as a Philadelphia (Ph') chromosome. The junction at the site of the translocation causes overexpression of a thymine kinase receptor. A new drug (Gleevec or imatinib) has been found to inhibit the disease if the patient is treated early.
   Why would Gleevec most probably cause remission of the disease? A) The drug inhibits the replication of the affected chromosome.
   B) It eliminates the Ph' chromosome. C) It removes Ph'-containing progenitor cells.
   D) It reverses the chromosomal translocation.
   E) The drug inhibits the specific thymine kinase receptor.
5. For a particular microarray assay (DNA chip), cDNA has been made from the mRNAs of a dozen patients' breast tumor biopsies. The researchers will be looking for
   A) a pattern shared among some or all of the samples that indicates gene expression differing from control samples.
   B) a pattern of fluorescence that indicates which cells are overproliferating.
   C) a group of cDNAs that match those in non-breast cancer control samples from the same
   population.
   D) a group of cDNAs that act differently from those on the rest of the grid.
   E) a particular gene that is amplified in all or most of the patient samples.

1. a E) The drug inhibits the specific thymine kinase receptor.
2. b A) a pattern shared among some or all of the samples that indicates gene expression differing from control samples
3. c 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.
4. d A) have turned off or slowed down the process of transcription
5. e D) the anterior- posterior axis

5 Multiple Choice Questions

1. all
   1. What is the function of reverse transcriptase in retroviruses?
      A) It translates viral RNA into proteins.
      B) It uses viral RNA as a template for making complementary RNA strands.
      C) It uses viral RNA as a template for DNA synthesis.
      D) It hydrolyzes the host cell's DNA. E) It converts host cell RNA into viral DNA.
   2. What viruses have capsids?
   3. You isolate an infectious substance that is capable of causing disease in plants, but you do not know whether the infectious agent is a bacterium, virus, viroid, or prion. You have four methods at your disposal that you can use to analyze the substance in order to determine the nature of the infectious agent.
      I. treating the substance with nucleases that destroy all nucleic acids and then determining whether it is still infectious
      II. filtering the substance to remove all elements smaller than what can be easily seen under a light microscope
      III. culturing the substance by itself on nutritive medium, away from any plant cells
      IV.treating the sample with proteases that digest all proteins and then determining whether it is still infectious
      Which treatment would you use to determine if the agent is a prion? A) I only
      B) II only
      C) III only
      D) IV only
      E) either I or IV
   4. You isolate an infectious substance that is capable of causing disease in plants, but you do not know whether the infectious agent is a bacterium, virus, viroid, or prion. You have four methods at your disposal that you can use to analyze the substance in order to determine the nature of the infectious agent.
      I. treating the substance with nucleases that destroy all nucleic acids and then determining whether it is still infectious
      II. filtering the substance to remove all elements smaller than what can be easily seen under a light microscope
      III. culturing the substance by itself on nutritive medium, away from any plant cells
      IV. treating the sample with proteases that digest all proteins and then determining whether it is still infectious
      If you already knew that the infectious agent was either bacterial or viral, which treatment would allow you to distinguish between these two possibilities?
      A) I
      B) II
      C) III
      D) IV
      E) either II or IV
2. C) embryonic stem cells are totipotent, and adult stem cells are pluripotent
   1. The fact that plants can be cloned from somatic cells demonstrates that
      A) differentiated cells retain all the genes of the zygote.
      B) differentiated cells contain masked mRNA.
      C) differentiation does not occur in plants.
      D) genes are lost during differentiation.
      E) the differentiated state is normally very unstable.
   2. In humans, the embryonic and fetal forms of hemoglobin have a higher affinity for oxygen than that of adults. This is due to
      A) the attachment of methyl groups to cytosine following birth, which changes the type of hemoglobin produced.
      B) pseudogenes, which interfere with gene expression in adults.
      C) histone proteins changing shape during embryonic development.
      D) identical genes that generate many copies of the ribosomes needed for fetal globin production.
      E) nonidentical genes that produce different versions of globins during development.
   3. In animals, embryonic stem cells differ from adult stem cells in that A) embryonic stem cells are localized to specific sites within the embryo, whereas adult stem
      cells are spread throughout the body.
      B) embryonic stem cells have fewer genes than adult stem cells.
      C) embryonic stem cells are totipotent, and adult stem cells are pluripotent.
      D) embryonic stem cells are pluripotent, and adult stem cells are totipotent.
      E) embryonic stem cells have more genes than adult stem cells.
   4. In recent times, it has been shown that adult cells can be induced to become pluripotent stem cells (iPS). In order to make this conversion, what has been done to the adult cells?
      A) Cytoplasm from embryonic cells is injected into the adult cells.
      B) An adenovirus vector is used to transfer embryonic gene products into adult cells.
      C) The nucleus of an embryonic cell is used to replace the nucleus of an adult cell.
      D) A retrovirus is used to introduce four specific regulatory genes.
      E) The adult stem cells must be fused with embryonic cells.
3. D) The BAC carries more DNA, the BAC can carry entire genes and their regulatory elements, and larger BACs are easier to store.
   1. Why are BACs preferred today rather than bacteriophages for making genomic libraries?
      A) The BAC can carry entire genes and their regulatory elements.
      B) The BAC carries more DNA.
      C) Larger BACs are easier to store.
      D) The BAC carries more DNA, the BAC can carry entire genes and their regulatory elements, and larger BACs are easier to store.
      E) The BAC can carry entire genes and their regulatory elements, and larger BACs are easier to store.
   2. Which of the following is one of the technical reasons why gene therapy is problematic?
      A) Most cells with an engineered gene do not produce gene product.
      B) Transferred genes may not have appropriately controlled activity.
      C) Most cells with engineered genes overwhelm other cells in a tissue.
      D) mRNA from transferred genes cannot be translated.
      E) Cells with transferred genes are unlikely to replicate
   3. Which of the following is an example of post-transcriptional control of gene expression?
      A) the folding of DNA to form heterochromatin
      B) the binding of transcription factors to a promoter
      C) the removal of introns and alternative splicing of exons
      D) the addition of methyl groups to cytosine bases of DNA
      E) gene amplification contributing to cancer
   4. In large scale, genome-wide association studies in humans, correlation is sought between
      A) large inversions that displace the centromere.
      B) lengthy sequences that might be shared by most members of a population.
      C) single nucleotide polymorphisms in two or more adjacent genes.
      D) single nucleotide polymorphisms found only in persons with a particular disorder.
      E) single nucleotide polymorphisms found in families with a particular introns sequence.
4. A) T4 protein and T4 DNA
   1. A bacterium is infected with an experimentally constructed bacteriophage composed of the T2 phage protein coat and T4 phage DNA. The new phages produced would have
      A) T4 protein and T4 DNA.
      B) a mixture of the DNA and proteins of both phages.
      C) T2 protein and T2 DNA.
      D) T2 protein and T4 DNA.
      E) T4 protein and T2 DNA.
   2. A principal problem with inserting an unmodified mammalian gene into a BAC, and then getting that gene expressed in bacteria, is that
      A) bacterial RNA polymerase cannot make RNA complementary to mammalian DNA.
      B) bacteria cannot remove eukaryotic introns.
      C) prokaryotes use a different genetic code from that of eukaryotes.
      D) bacterial DNA is not found in a membrane-bounded nucleus and is therefore
      incompatible with mammalian DNA. E) bacteria translate polycistronic messages only.
   3. How does a bacterial cell protect its own DNA from restriction enzymes? A) by adding histones to protect the double-stranded DNA
      B) by forming "sticky ends" of bacterial DNA to prevent the enzyme from attaching
      C) by adding methyl groups to adenines and cytosines
      D) by reinforcing the bacterial DNA structure with covalent phosphodiester bonds
      E) by using DNA ligase to seal the bacterial DNA into a closed circle
   4. A geneticist introduces a transgene into yeast cells and isolates five independent cell lines in which the transgene has integrated into the yeast genome. In four of the lines, the transgene is expressed strongly, but in the fifth there is no expression at all. Of the lines that express the transgene, one is transcribed but not translated. Which of the following is a likely explanation?
      A) high histone acetylation
      B) no compatible ribosome
      C) missing transcription factor
      D) no AUG in any frame
      E) no promoter
5. C) organismal cloning
   1. Which of the following is most closely identical to the formation of twins?
      A) therapeutic cloning
      B) embryo transfer
      C) organismal cloning
      D) cell cloning
      E) use of adult stem cells
   2. Which of the following is a protein produced by a regulatory gene? A) operon
      B) inducer
      C) corepressor
      D) repressor
      E) promoter
   3. Which of the following represents a difference between viruses and viroids?
      A) Viruses have capsids composed of protein, whereas viroids have no capsids.
      B) Viruses cannot pass through plasmodesmata, whereas viroids can.
      C) Viruses contain introns, whereas viroids have only exons.
      D) Viruses infect many types of cells, whereas viroids infect only prokaryotic cells.
      E) Viruses always have genomes composed of DNA, whereas viroids always have genomes composed of RNA.
   4. Which of the following is characteristic of the lytic cycle?
      A) The virus-host relationship usually lasts for generations.
      B) Many bacterial cells containing viral DNA are produced.
      C) Viral DNA is incorporated into the host genome.
      D) The viral genome replicates without destroying the host.
      E) A large number of phages are released at a time.

5 True/False Questions

1. 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
   marrow.
   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. → C) The engineered cells, when reintroduced into the patient, find their way back to the bone marrow

   True        False

2. Which of the following is characteristic of the product of the p53 gene?
   A) It causes cell death via apoptosis.
   B) It speeds up the cell cycle.
   C) It allows cells to pass on mutations due to DNA damage.
   D) It slows down the rate of DNA replication by interfering with the binding of DNA polymerase.
   E) It is an activator for other genes. → E) a large number of phages are released at a time

   True        False

3. 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 → B) increased chromatin condensation

   True        False

4. If a particular operon encodes enzymes for making an essential amino acid and is regulated like the trp operon, then
   A) the amino acid inactivates the repressor.
   B) the amino acid acts as a corepressor.
   C) the repressor is active in the absence of the amino acid.
   D) the enzymes produced are called inducible enzymes.
   E) the amino acid turns on transcription of the operon. → A) a pattern shared among some or all of the samples that indicates gene expression differing from control samples

   True        False

5. Some viruses can be crystallized and their structures analyzed. One such virus isDesmodium, or yellow mottle virus, which infects beans. This is a member of the tymovirus group and has a single-stranded RNA genome of ~6,300 nucleotides. Its virion is 25—30 nm in diameter, and is made up of 180 copies of a single capsid protein that self-associate to form each capsomere, which has icosahedral symmetry with 20 facets.
   If this virus has a positive RNA strand as its genome, it begins the infection by using this strand as mRNA. Therefore, which of the following do you expect to be able to measure?
   A) translation rate
   B) formation of new transcription factors
   C) accumulation of new ribosomes D) transcription rate
   E) replication rate → E) retroviruses

   True        False