MCB 150 Practice Exam III, Fall 2012 1 1. Consider the following two statements about the use of fluorescence in cell biology: 1) Fluorescence can be used to identify the sites of initiation of DNA replication during M-phase. 2) Fluorescence can be used to identify the location of chromosomes relative to each other during interphase. Determine which one of the statements below is correct. A. Statement 1) and statement 2) are both true. B. Statement 1) and statement 2) are both false. C. Statement 1) is true; statement 2) is false. D. Statement 1) is false; statement 2) is true. 2. The gene which codes for the dystrophin protein in humans is called DMD. A mutation leading to a genotype of DMD— would most likely take the form of a(n) mutation. A. frameshift B. deletion C. same sense D. insertion E. duplication 3. Which one of the following statements about the human mitochondrial genome is incorrect? A. All of the proteins coded for on the mitochondrial genome are involved with electron transport or oxidative phosphorylation. B. The mitochondrial genome codes for all the tRNAs necessary to carry out translation in the matrix. C. Transcription of protein coding genes in the mitochondria would be dependent on Type II transcription factors. D. Translation in the matrix occurs using ribosomes with rRNA components that were themselves transcribed in the matrix. E. A mitochondrial genome possesses an origin of replication and can be copied in a manner similar to bacterial chromosome replication.MCB 150 Practice Exam III, Fall 2012 2 4. Which of the following pathways is the protein "secretory pathway" used by eukaryotic cells? A. RER à Golgi à secretory vesicles à cytoplasm à outside of the cell B. nucleus à RER à Golgi à secretory vesicles à outside of the cell C. RER àà Golgi àà secretory vesicles àà outside of the cell D. nucleus à RER à cytoplasm à outside of the cell E. RER à SER à Golgi à outside of the cell 5. The cellular machinery that synthesizes ceramide is located in the ; the cellular machinery that converts ceramide to a glycolipid is located in the _____________. A. Golgi apparatus; smooth endoplasmic reticulum B. smooth endoplasmic reticulum; smooth endoplasmic reticulum C. Golgi apparatus; Golgi apparatus D. rough endoplasmic reticulum; smooth endoplasmic reticulum E. smooth endoplasmic reticulum; Golgi apparatus 6. Arrange the following from largest to smallest. i. muscle fiber ii. myofibril iii. muscle iv. sarcomere v. muscle bundle A. i, iii, v, ii, iv B. iii, v, i, ii, iv C. iii, v, i, iv, ii D. iv, ii, i, v, iii E. v, iii, ii, i, iv 7. The discovery and subsequent study of polytene chromosomes helped to validate which one of the following hypotheses? A. Euchromatin is transcribed; heterochromatin is not transcribed. B. Chromosomes occupy their own territories during interphase. C. Nuclear export signals take the form of amino acid sequences and not nucleotide sequences. D. The nucleolus is the site of ribosomal subunit production. E. The discovery and subsequent study of polytene chromosomes helped to validate each of the above hypotheses.MCB 150 Practice Exam III, Fall 2012 3 8. An already-incorporated deoxyribonucleotide which is damaged during G1 is most likely to be corrected by repair, which is a type of repair. A. excision; specific B. SOS; specific C. photoreactivation; error-prone D. mismatch; non-specific E. proofreading; specific 9. True or False: In an electron micrograph of rough endoplasmic reticulum, some of the ribosomes attached to the ER membrane are actively carrying out translation, while others are awaiting a messenger RNA to recognize and translate. A. True B. False 10. The concentration of protons in the lumen of a functioning lysosome is approximately than the concentration of protons in the cytoplasm. A. 2 times higher B. 2 times lower C. 10 times higher D. 10 times lower E. 100 times higher 11. The critical concentration (Cc) of the plus end of an actin filament is 0.1 µM, while the Cc of the minus end of the filament is 0.6 µM. If the actual concentration of available ATP-bound G-actin at both ends of this filament is 0.3 µM, which one of the following statements most likely describes the behavior of this actin filament? [Note: don't focus on the micromolar units (µM); it's the relative amounts that are important for this question.] A. This filament will be depolymerizing at the plus end and polymerizing at the minus end. B. This filament will be depolymerizing at the minus end and exhibiting no net growth at the plus end. C. This filament will be polymerizing at both the plus and minus ends. D. This filament will be polymerizing at the plus end and depolymerizing at the minus end. E. This filament will be polymerizing at the plus end and exhibiting no net growth at the minus end.MCB 150 Practice Exam III, Fall 2012 4 The following figure shows electron micrographs of nuclei from cells in different phases of the cell cycle. Use the following figure to answer the next three (3) questions. 12. In Cell (1), the RNA component of the 40S ribosomal subunit is transcribed in the region labeled: A. (F). B. (D). C. (A). D. (C). E. (B). 13. Which one of the cells in the figure above could be actively engaged in DNA replication? A. Cell (1) only B. Cell (2) only C. Both Cell (1) and Cell (2) could be actively engaged in DNA replication. D. Neither Cell (1) nor Cell (2) could be actively engaged in DNA replication. 14. Which one of the following structures or molecules is least likely to be found in the region labeled (C)? A. snoRNPs B. snRNPs C. The transcription factor TFIA D. Ribosomal protein E. 5S rRNAMCB 150 Practice Exam III, Fall 2012 5 15. Which one of the following base pair substitutions is most likely to interfere with the correct cellular localization of a Krebs cycle enzyme? Consult the codon table and table of amino acids side chains attached to this exam packet if necessary. A. AAG → AAA B. CGA → AGA C. AAA →→ AUA D. CGU → CGG E. AGG → AAG 16. A transmembrane protein found in the cytoplasmic membrane is oriented as shown in the following figure, where “N” is the amino terminus of the protein and