Biology 151C Dr Caleb Rounds Exam II Fall 2013 CE DIRECTIONS BEFORE DOING ANYTHING FILL IN YOUR NAME AND ID QUESTIONS WITH LETTERS ARE MULTIPLE CHOICE QUESTIONS WITH NUMBERED ANSWERS ARE MULTIPLE TRUE FALSE WHERE A IS TRUE AND B IS FALSE 1 Are you in Dr Caleb Rounds Introductory Biology 151C class that meets Tuesday Thursday at 2 30 in Room 135 of the ISB A Yes and I ve filled in my ID number and the appropriate bubbles on the form B No I d like to decline the free point and I m insulted that you would suggest I don t want to earn my score solely on the basis of what I ve learned C Wait biology 2 Mannose is a relatively rare sugar in the human diet so E coli would not often need to subsist on it Given this information what type of expression regulation do you think would be most likely A B C D Positive Negative inducible Negative repressible Epigenetic 3 Breaking a peptide bond involves A B C D E Adding a water molecule The loss of a water molecule to the surrounding system Hydrogen bonding Electrolysis Compensation 4 Intramolecular bonds important for holding sheets together A Hydrophobic bonds B Covalent bonds between sheets C Ionic bonds D Hydrogen bonds E Disulfide bonds 5 The protein pore in the ER that allows for co translational import includes alpha helices that face the membrane along one side and the aqueous pore on the other These alpha helices are likely A B C D E To consist of a random mixture of hydrophobic and hydrophilic amino acids To be either hydrophobic or hydrophilic To have R groups along one side which are hydrophobic To have some R groups facing in towards the core of the alpha helix To consist of amphiphilic amino acids Biology 151C Dr Caleb Rounds Exam II Fall 2013 CE 2 1 3 6 In the replica plating experiment shown above plate 3 has complete media plate 1 has minimal media plus amino acids and plate 2 has minimal media What might be the problem with strain C A B C D E Strain C is unable to import one or more amino acids Strain C is unable to synthesize one or more amino acids Strain C is unable to break down excessive amounts of an amino acids Strain C is unable to repress the expression of amino acid biosynthesis enzymes Any of the above are possible 7 If the replica plating experiment shown above were designed to test the ability of E coli mutants to metabolize lactose what media would be in plates 1 2 and 3 in that order A B C D E Complete media minimal media lactose glucose minimal media Minimal media Minimal media lactose glucose complete media Minimal media lactose glucose minimal media complete media Minimal media lactose minimal media glucose complete media Minimal media lactose minimal media lactose complete media 8 In the replica plating experiment shown above we can assume that A B C D E A on plate 3 and A on plate 2 are genetically identical C on plate 1 has some sort of mutation B on plate 2 and on plate 1 are different genetically A and B are correct B and C are correct Biology 151C Dr Caleb Rounds Exam II Fall 2013 CE 9 Meat is made of a diverse group of proteins including myoglobin actin myosin and tropomyosin You take a piece of flank steak and cut it in half One half you cook and the other you keep cold Afterwards you extract protein from both and run them on a gel How could you identify the actin A B C D E It would be larger in the cooked sample It would be smaller in the cooked sample Actin would be the same size You could perform a western blot with an appropriate antibody You could add radioactive amino acids before cooking the meat 10 In an experiment concerning E coli metabolism of fructose a mono saccharide you test all of the characteristics shown in the table below Given what you know about catabolic pathways in E coli what is a possible mutation fructase is the fictional enzyme that digests fructose Experiment Fructose only media Expression of Fructase Fructose in cell A B C D E WT Grows Yes Yes Mutant Doesn t grow Yes No Fructase is repressed inappropriately The fructose membrane transporter fructose permease is not expressed Fructase is non functional Impossible to tell from the given information It could be A or C Multiple True False 11 Two consecutive amino acids in the primary structure are never near each other in tertiary structure F 12 The first amino acid at the N terminus and last amino acid at the C terminus are never near each other in tertiary structure F 13 Proteins never have both alpha helices and beta sheets F 14 All the information for forming the tertiary structure is in the primary structure T 15 Substitution of a single amino acid should not affect the mobility of the protein in SDSPAGE T 16 Which of the following is not a requirement for import across a membrane A B C D E A pore An energy source A signal sequence A receptor A radioactive amino acid Biology 151C Dr Caleb Rounds Exam II Fall 2013 CE 17 In the experiment above radioactive methionine was added to the media for a 20 minute pulse followed by a non radioactive media for two hours The first lane represents the protein translated with no ER present Lanes 2 4 are from temperature sensitive cells grown at the non restrictive or permissive temperature Lanes 5 6 represent cells from the same mutant grown at the restrictive temperature Use this information and the experiment to answer the following questions Why is the band in lane 4 higher than the band in lane 1 A B C D It has had its signal peptide cleaved It is in the membrane It may have been glycosylated It is now folded Which of the following are potential mutations in the temperature sensitive line multiple true false 18 19 20 21 22 23 Signal peptide cutting enzyme is mutated F A GTPase involved in golgi ER movement F A GTPase involved in ER golgi movement T The enzyme that performs glycosylation T Ubiquitination is not occurring properly F The receptor for ER targeting F 24 Is the protein shown a membrane protein A Yes B No C It is impossible to tell from the given information Biology 151C Dr Caleb Rounds Exam II Fall 2013 CE Your boss wishes to know about the role of a certain protein in the cell He s particularly interested in whether it is involved in protein trafficking You perform an experiment to answer this question by translating the protein in the presence or absence of the ER and a cytosolic cell extract You then treat samples with a non membrane penetrating protease and a detergent as indicated Finally you run the gel shown and perform a western blot with antibodies specific to