BIOS 390 ERIC KYLE Week 6 Exam Study Guide
BIOS 390
Week 6 Exam Study Guide/Assignment And Answers
Question Set 1
(TCO 8) Which statement is not true
... [Show More] about the nucleolus? (Select the correct answer.)
• The nucleolus is the site of rRNA synthesis.
• The nucleolus is a membrane-bound organelle within the nucleus.
• The nucleolus is the site of ribosome subunit assembly.
• The nucleolus is composed of a fibrillar center, dense fibrillar component, and granular component.
(TCO 8) Ribosomes carry out the process of protein synthesis in the _____ after assembly in the _____ within a special compartment called the _____.
Ribosomes function in the cytoplasm, but their assembly occurs in the nucleus, within a special subcompartment called the nucleolus.
(TCO 8) Which of the following is not a function of ribosome in protein synthesis?
• Decoding the genetic code of mRNA
• Charging the tRNA with the amino acid
• Binding to tRNA delivering the amino acid
• Catalyzing peptide bond formation.
Question Set 2
(TCO 8) What is an anticodon? A sequence of three adjacent nucleotides in tRNA designating a specific amino acid that binds to a corresponding codon in mRNA during protein synthesis.
(TCO 8) Aminoacyl-tRNA synthetases are enzymes that 1. Aminoacyl tRNA synthetases are enzymes that attach a specific amino acid to a specific tRNA molecule.
2. They are very important for the accurate transmission of information from nucleic acids to proteins.
3. The attachment of a given amino acid to a particular tRNA establishes the genetic code.
4. The formation of a peptide bond between free amino acids is not thermodynamically favorable. The amino acid must first be activated in order for protein synthesis to proceed.
5. The activated intermediates in protein synthesis are amino acid esters, in which the carboxyl group of an amino acid is linked to either the 2' - or the 3'-hydroxyl group of the at the 3' end of the tRNA.
(TCO 8) Transfer RNAs get charged with amino acids (where?) must join together in the cytoplasm.
Question Set 3
(TCO 8) GTP hydrolysis is required for (Select the best answer.)
• joining of the 40S and 60S subunits.
• peptide bond formation.
• start codon recognition and initiation factor release.
• both joining of the 40S and 60S subunits and start codon recognition and initiation factor release.
(TCO 8) Hydrolysis of ATP indirectly fuels protein synthesis by generating a high energy bond between the amino acid and the tRNA
(TCO 8) Protein synthesis is an anabolic process. Energy is provided by hydrolysis of
GTP hydrolysis
Question Set 4
(TCO 8) Which is not a member of the eukaryotic ternary complex of translation initiation?
• Met-tRNA
• eIF2
• mRNA
• GTP
(TCO 8) The start codon for translation in eukaryotes is
(TCO 8) Initiation factors with helicase activity (eIF4G, eIF4E) associate with
• ribosomes.
• 5’ end of mRNA.
• 3’ end of mRNA.
• PABPN1.
Question Set 5
(TCO 8) The stop codon is recognized by
Stop codons are recognized by Release factor (which is a protein) during translation termination and cause the release of management molecule from the ribosome.
(TCO 8) Nascent polypeptides exit the ribosome via One of the key features of the ribosome is the long “tunnel” that conducts the nascent protein through the large subunit from the site of peptidyl transferase activity to the peptide exit hole
(TCO 8) The signal recognition particle (SRP) is a ribonucleoprotein complex that binds to ribosomes translating polypeptides that bear a signal sequence for targeting to the endoplasmic reticulum (ER).
Question Set 6
(TCO 8) When the translation initiation factor eIF2 is phosphorylated in response to a sudden temperature increase or viral infection, translation can be greatly inhibited. In this case, phosphorylated eIF2 is under _____ control, and the phosphorylation of eIF2 leads to global (general or widespread) _____ control. post-translational; translational
(TCO 8) In response to unfavorable conditions, such as hypoxia or osmotic shock, translation can be globally repressed by
• modification of mRNA 7-methylguanosine caps.
• ribosome stalling via a conformation change in eEF2.
• phosphorylation of eIF2α.
• puromycin synthesis.
(TCO 8) Phosphorylation of eIF2αblocks translation by
• preventing initiation of translation.
• preventing elongation of translation.
• preventing termination of translation.
• supercoiling the mRNA such that the start codon is not available.
Question Set 7
(TCO 8) Many steps in gene expression and cell signaling involve post-translational modification of proteins by phosphorylation.
(TCO 8) Which of the following is not true about molecular chaperones?
• They decrease the efficiency of the overall process of protein folding.
• Some of them enhance the rate of formation of disulfide bonds.
• They reduce the probability of protein aggregation.
• They aid in the destruction of misfolded proteins.
(TCO 8) Allosteric regulation always involves a protein's function at one site is affected by binding of a regulatory molecule at another site, Allosteric regulation may either inhibit or stimulate an enzyme's activity.
Question Set 8
(TCO 8) You determine that a protein has an attached polyubiquitin chain. It is likely that this protein will be targeted to the 26s proteasome for degradation
(TCO 8) Alzheimer’s disease, Huntington’s disease, and Creutzfeldt-Jakob disease are all examples of
• transmissible spongiform encephalopathy.
• trinucleotide repeat disorders.
• protein misfolding diseases.
• diseases that are not related in any way.
(TCO 8) A prion is an infectious protein with the surprising ability to replicate itself within the body. The infectious protein was designated scrapie prion protein (PrPSc). The next surprising discovery was that the prion PrPSc has the same amino acid sequence as a normal host protein (PrPC) encoded by a cellular gene. The only difference between the normal and infectious proteins lies in their structure. PrpSc has an altered three-dimensional folding pattern compared with PrpC.
Question Set 9
(TCO 9) When making a transgenic mouse by microinjection of foreign DNA into fertilized eggs,
• there is random integration of the transgene into the embryonic genome.
• there is disruption or mutation of a targeted gene in the embryonic genome.
• the resulting mice are genetically identical to the donor nucleus.
• the integration event into the embryonic genome usually occurs by homologous recombination.
(TCO 9) When making transgenic mice, to determine whether there has been stable integration of a transgene into the mouse chromosome, tail biopsies are taken from the mouse pups and tested for the presence of the transgene by Southern blot hybridization or polymerase chain reaction (PCR).
(TCO 9) When cloning an organism by nuclear transfer,
• there is random integration of a transgene into the recipient cell’s nuclear genome.
• there is disruption or mutation of a targeted gene in the resulting organism.
• the resulting organism is genetically identical to only the donor nucleus and not the recipient
• the cytoplasm of the donor cell is transferred to the recipient cell.
Question Set 10
(TCO 9) Pharming is
• the growth of transgenic plants as food crops.
• the use of genetically modified organisms to produce pharmaceutical age
• the use of plants or algae to produce biofuels.
• the use of Agrobacterium tumefaciens to transform animal cells. ...
(TCO 9) Which of the following is not a suspected reason for the inefficiency/poor outcomes of reproductive cloning?
• Inefficient reprogramming
• Disruption of gene of interest by random integration
• Telomere length
• Chromosome mis-segregation during early embryonic divisions
(TCO 9) The term reprogramming refers to An enucleated oocyte can reprogram an adult nucleus into an embryonic state after somatic cell nuclear transfer, so that a new organism can be developed from such cell.
Question Set 11
(TCO 9) Plasmids are used as vectors in both plant and bacterial recombinant DNA technology. However, there is a major difference in the fate of genes introduced into bacteria on most bacterial plasmids and into plants on Ti plasmids. What is this difference? Bacterial plasmids and the genes they carry usually are not integrated into the chromosome; Ti plasmids and the genes they carry are integrated into the chromosome.
(TCO 9) Which is not a method by which one can introduce foreign DNA into a plant cell?
• Calcium chloride treatment followed by heat shock
• Infection with a specific bacterium
• Microballistic gene gun
• Electroporation
(TCO 9) Find the incorrect statement.
• Ti plasmid-based gene delivery system for plants is highly efficient.
• Differentiated plant cells are totipotent.
• Ti plasmids do not need any selectable markers.
• Plants can also be manipulated by microballistic transfection.
Question Set 12 (On your exam, one of the following 3 questions will be your short answer question.)
(TCO 8) Mammalian ribosomes are composed of a 60S and a 40S subunit. What is S? Svedberg Unit
A unit of sedimentation rate during centrifugation. One Svedberg unit equals a sedimentation coefficient of 10−13 seconds. Abbreviation is S; named after the physical chemist, Theodor Svedberg.
The large and small subunits of mammalian ribosomes are known as 60S and 40S, respectively. The 60S subunit includes an additional 5.8S rRNA. The sequence of the 5.8S rRNA corresponds to the 3′ end of the bacterial 23S rRNA.
(TCO 8) Discuss the roles of molecular chaperones in protein folding and degradation.
Molecular chaperones increase the efficiency of the overall process of protein folding by reducing the probability of competing reactions, such as aggregation. ATP is required for most of the molecular chaperones to function with full efficiency. Molecular chaperones include heat-shock proteins, such as Hsp40, Hsp70, and Hsp90, which promote protein folding and aid in the destruction of misfolded proteins. The designation of these as heat-shock proteins reflects the fact that their concentrations are substantially increased during cellular stress. Hsp70 functions as a chaperone in association with Hsp40, while Hsp90 functions as a chaperone by interacting with another protein named p23. The dramatic shape changes that Hsp90 undergoes while carrying out its function are truly remarkable. Regulation of protein folding. By associating with exposed hydrophobic domains, molecular chaperones Hsp70 and Hsp40 promote the folding of newly synthesized proteins. Alternatively, they can interact with misfolded proteins, promoting their degradation by the ubiquitin–proteasome system. Many newly synthesized proteins are translocated to the endoplasmic reticulum, where they fold with the help of molecular chaperones. Correctly folded proteins are transported to the Golgi complex and then secreted from the cell. Misfolded proteins are detected by a quality control mechanism and targeted for degradation.
(TCO 8) Describe possible fates for a misfolded protein in a cell. Misfolded proteins are targeted for degradation by the ubiquitin-mediated protein degradation pathway. In this pathway, a chain of ubiquitin molecules is attached to the misfolded protein by means of a series of enzymatic reactions. Polyubiquitin targets the protein to the proteasome for proteolytic degradation.
Misfolded proteins are handled by a cell in the following ways:
1. Protein synthesis of such proteins are stopped, rectified and then again initiated
2. Misfolded proteins are rectified in the proteasomes complex
3. Misfolded proteins are degraded in the proteasomes complex
Protein misfolding is linked to a number of diseases, including neurodegenerative disorders such as Alzheimer’s disease and transmissible spongiform encephalopathies (prion diseases). Misfolded proteins aggregate to form toxic deposits known as amyloid (or amyloid-like) fibrils. [Show Less]