MCB 150 Practice Exam III Fall 2012 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 other during interphase 2 Fluorescence can be used to identify the location of chromosomes relative to each 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 frameshift A B deletion C D E same sense insertion 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 C Transcription of protein coding genes in the mitochondria would be dependent on in the matrix 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 1 MCB 150 Practice Exam III Fall 2012 4 Which of the following pathways is the protein secretory pathway used by eukaryotic cells A RER Golgi secretory vesicles cytoplasm outside of the cell B nucleus RER Golgi secretory vesicles outside of the cell C RER Golgi secretory vesicles outside of the cell D nucleus RER cytoplasm outside of the cell E RER SER Golgi outside of the cell The cellular machinery that synthesizes ceramide is located in the cellular machinery that converts ceramide to a glycolipid is located in the A Golgi apparatus smooth endoplasmic reticulum B C Golgi apparatus Golgi apparatus D E rough endoplasmic reticulum smooth endoplasmic reticulum smooth endoplasmic reticulum Golgi apparatus smooth endoplasmic reticulum smooth endoplasmic reticulum the 6 Arrange the following from largest to smallest 5 i muscle fiber ii myofibril iii muscle iv sarcomere v muscle bundle i iii v ii iv A iii v i ii iv B iii v i iv ii C 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 2 MCB 150 Practice Exam III Fall 2012 8 An already incorporated deoxyribonucleotide which is damaged during G1 is most likely to be corrected by repair which is a type of repair excision specific A B SOS specific C photoreactivation error prone D mismatch non specific E proofreading specific A True B False A 2 times higher B 2 times lower C 10 times higher D 10 times lower E 100 times higher 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 10 The concentration of protons in the lumen of a functioning lysosome is approximately than the concentration of protons in the cytoplasm 11 The critical concentration Cc of the plus end of an actin filament is 0 1 M while the Cc of the minus end of the filament is 0 6 M If the actual concentration of available ATP bound G actin at both ends of this filament is 0 3 M which one of the following statements most likely describes the behavior of this actin filament Note don t focus on the micromolar units M 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 B This filament will be depolymerizing at the minus end and exhibiting no net growth at 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 E This filament will be polymerizing at the plus end and exhibiting no net growth at the end the plus end end minus end 3 MCB 150 Practice Exam III Fall 2012 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 B C D E F D A C 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 snoRNPs snRNPs labeled C A B C The transcription factor TFIA D Ribosomal protein E 5S rRNA 4 MCB 150 Practice Exam III Fall 2012 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 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 C is the carboxy terminus of the protein Which one of the following most accurately represents the identity and location of targeting signals in the protein shown above A AAG AAA B CGA AGA C AAA AUA D CGU CGG E AGG AAG A B C D E A True B False 17 True or False A mannose 6 phosphate receptor molecule being recycled to the Golgi apparatus is allowed to return to the trans Golgi instead of entering the cis Golgi and traveling through the Golgi stack 5 MCB 150 Practice Exam III Fall 2012 18 Which one of the following statements about actin is incorrect A Actin filaments are polymerized in head to tail fashion B Actin is highly conserved among organisms which possess it C Actin is one of the most