Sample exam questions from Bio 93 Final Exam: Fall 2012 Dr. Williams 1. The DNMT gene in humans codes for several enzymes that add methyl groups to DNA. This is an example of: A. RNA processing B. Degradation of mRNA C. Control of DNA replication D. Chromatin modification 2. In an action potential, the falling phase is triggered by: A. Opening of voltage gated channels B. Opening of ligand gated channels C. Opening of leaky channels 3. A mutation in the gene that codes for fibrinogen causes developmental problems and joint pain in adults. This is an example of: A. Pleiotropy B. Epistasis C. Codominance D. Polygenic inheritance 4. The Drosophila oocyte extends microtubules into the nurse cells and dynein transports bicoid into the oocyte via dynein. Where are the minus ends of the microtubules? A. Oocytes B. Nurse cells 5. For a diploid organism whose somatic cells have 2 pairs of homologous chromosomes, which of the following represents a cell at the end of meiosis 1 ? (letter choices shown under cells) 6. A 2009 article in the British newspaper The Telegraph was titled: “A veterinarian has adopted a tortoiseshell cat that she claims is a ‘genetic impossibility’ because it is male.” What is the likely genotype of the sex chromosomes in this cat? A. X Bio 93 Final Exam Section F 2012 - A Page 1 of 9 B. C. D. E. Y XY XXY XX 7. A cell line is mutated so that it contains nonfunctional kinetochores. Which would happen first? A. Spindle fibers would not form B. Chromosomes would not line up at the metaphase plate C. Chromosomes would not duplicate D. Sister chromatids would not separate 8. A 2010 research paper examined the effect of a synonymous substitution on the CFTR gene, the malfunction of which causes the disease cystic fibrosis. Their findings are given below: CFTR protein DNA codon Amino acid mRNA structure expression level ATC (normal) Isoleucine Normal ATT (CF disease) Isoleucine Low Which conclusion is most consistent with these results? A. Mutations that do not affect primary amino acid sequence can affect translation efficiency B. Changes in mRNA folding can affect its insertion into the plasma membrane C. A mutation in DNA may be corrected when it is transcribed into mRNA 9. A researcher is attempting to create a vaccine that would make a population of coyotes sterile but otherwise healthy. Which would be the most useful avenue of research to pursue? A. Prevent chromosome duplication B. Prevent formation of tetrads C. Remove dynein from kinetochores Bio 93 Final Exam Section F 2012 - A Page 2 of 9 10. Water molecules are released every time a nucleotide is added to the daughter strand of replicating DNA. Which of the following is causing this release? A. Removal of phosphates from the new nucleotide B. Action of helicase to separate the strands C. Binding of the nucleotide to the daughter strand 11. A strand of mRNA reads 5’ UGG UUU 3’. What is the sequence of the coding strand of DNA from 5’ to 3’? A. TGG TTT B. ACC AAA C. AAA CCA 12. The disease phenylketonuria (PKU) is caused by a mutation for the gene that codes for the enzyme phenylalanine hydroxylase. Without a working enzyme, levels of phenylalanine in the blood are high and can cause mental retardation. A table of hydroxylase activity and phenylalanine concentrations is given here: Genotype Hydroxylase activity Blood phenylalanine Has PKU? concentration AA 100 % 60 uM No AB 30 % 120 uM No BB 0.3 % > 600 uM Yes This table indicates: A. Only homozygous AA individuals produce sufficient hydroxylase to prevent PKU B. PKU is an autosomal dominant disease C. Allele A is incompletely dominant over B at the molecular level 13. Pea pods are normally green because they manufacture chlorophyll pigment which is green. The recessive allele codes for a yellow pod, and yellow-pod plants are generally less vigorous. We can conclude: A. The recessive allele codes for a nonfunctioning enzyme in the chlorophyll formation pathway B. Homozygous recessives form recessive chlorophyll pigments C. Homozygous dominant plants contain twice as much chlorophyll as homozygous recessive plant 14. Black (B) and white (b) plumage in chickens shows incomplete dominance. What are the genotypes of the parents if the progeny are present in a 0:1:1 ratio of black:grey:white? A. BB and bb B. Bb and bb C. Bb and Bb D. BB and Bb Bio 93 Final Exam Section F 2012 - A Page 3 of 9 15. “Crisscross inheritance” describes a pedigree where an affected male passes a gene to his unaffected daughter, who gives it to her affected son. This would describe the inheritance of: A. Sickle cell anemia B. Color blindness C. Cystic fibrosis 16. The “white” and “forked” genes in flies have a recombination frequency of about 30% when a test cross is performed with a dihybrid fly. Of the 1000 offspring, how many are likely be the parental type? A. 312 B. 501 C. 708 D. 1000 17. In cancer, tumor cells often cause changes in DNA sequence including deletions and translocations. In an article published in November 2012, researchers tested the blood for free DNA in healthy patients and known cancer patients, and were able to determine the presence of cancer without surgery on the tumor. Which technique would the researchers used to find these chromosomal changes in multiple chromosomes? A. Mass spectrometry B. Next generation sequencing C. mRNA sequencing 18. In protein sequencing, a number of bonds must be broken in order to create small enough peptides for the mass spectrometer. Which of the following is NOT a bond that will be broken? A. Ester B. Peptide C. Hydrogen D. Disulfide 19. A male Drosophila is irradiated in a genetic screen experiment, producing a mutant bicoid gene in its sperm. When the male is mated to a normal female the offspring: A. Will have two tails B. Will be unaffected carriers C. Will produce all two-tailed progeny 20. In both the cortical reaction and the muscle cell: A. An electrical signal travels along the first cell (sperm / motor neuron) B. Cell surface signalling is used to trigger a response in the second cell (egg / muscle cell) C. The smooth ER is used as a calcium storage organelle 21. Unlike maternal factors, inducer molecules are: A. Important for gene activation B. Secreted proteins Bio 93 Final Exam Section F 2012 - A Page 4 of 9 C. Seen in the zygote of sea urchins D. Often mRNA 22. The elongation of microtubules is seen in both: A. Acrosome reaction; migration of mesoderm cells in gastrulation B. Delivery of bicoid to Drosophila egg, cytokinesis during early blastula C. Formation of dorsal lip; neural tube formation 23. Depolarization of a cell membrane is seen in both mature neurons and: A. Cells undergoing meiosis B. Fertilized sea urchin eggs C. Frogs undergoing gastrulation D. Neural plate cells 24. Synaptic vesicles fuse with the presynaptic membrane in response to: A. Increased calcium in the cytosol B. neurotransmitter released from the postsynaptic cell C. The presence of Botulinum toxin D. Membrane hyperpolarization 25. The disease myasthenia gravis is characterized by muscle weakness. Measurements of membrane potentials before and after stimulation of the motor neuron are as follows: Timing Presynaptic terminal Muscle membrane T tubule Before stimulation -70 mV -70 mv After stimulation 30 mV -20 mV Which hypothesis about the cause of this disease does this data support? A. The calcium channels are overstimulated B. The acetylcholine receptors are damaged C. The sodium potassium pumps in the muscle cell do not function D. The sodium potassium pumps in the motor neuron do not function -70 mV -70 mV 26. LDL complexes carry cholesterol in the blood and consist of protein, phospholipids, cholesterol and small fatty acids. In the diagram of a section through an LDL complex, which of the following symbols, indicated by X, Y or Z, is most likely to represent fatty acid molecules called linoleate? A. X B. Y C. Z 27. Cholesterol is transported by LDL complexes because it: Bio 93 Final Exam Section F 2012 - A Page 5 of 9 A. B. C. D. Is too small to travel alone It cannot freely diffuse across membranes Would disrupt the plasma osmolarity and cause cells to swell Is hydrophobic and does not dissolve well in blood 28. LDL receptors are part of what membrane transport system? A. Cotransport B. Phagocytic extension C. Receptor-mediated endocytosis D. Pinocytosis E. Facilitated diffusion 29. A cell is fluorescently labeled with a probe that binds to LDL receptors. When examined, the following is found: Location Vesicles transported Vesicles transported Plasma by kinesin by dynein membrane Amount of High Low Low fluorescence Which of the following hypotheses supports this result? A. The cell requires additional cholesterol B. The cell is currently importing large amounts of LDL C. The cell regularly takes up cholesterol 30. Formation of LDL receptors involves A. hydrolysis reactions forming ester bonds B. dehydration reactions forming ester bonds C. dehydration reactions forming peptide bonds D. hydrolysis reactions forming peptide bonds 31. The most likely fate of cholesterol absorbed by a cell is the manufacture of: A. Steroid hormones B. Integral membrane proteins C. Microtubules D. Nucleic acids E. Carbohydrates 32. The structure of linoleate, a fatty acid found inside an LDL complex is diagrammed in this image. This molecule is: A. Hydrophilic based on the presence of carbon-carbon double bonds B. Unsaturated and dominated by nonpolar covalent bonds C. Saturated and dominated by polar covalent bonds Saturated and dominated by ionic bonds Bio 93 Final Exam Section F 2012 - A Page 6 of 9 33. The cholesterol brought into the cell by an LDL complex is often modified by an enzyme called sterol Oacyltransferase. If no cellular energy in the form of ATP or GTP is needed for this reaction: A. there is no activation energy B. this is a form of passive diffusion C. the free energy of the products is lower than the reactants 34. Linoleate is transported into the mitochondria and is broken into 2-carbon molecules called Acetyl-CoA. Given their location, they must enter cellular respiration at: A. Citric acid cycle B. Glycolysis C. Oxidative phosphorylation 35. Plants also manufacture fatty acid molecules like linoleate. Which photosynthetic reaction would produce the carbon building blocks for a fatty acid molecule? A. Light reactions B. Calvin cycle Oxidative phosphorylation C. Substrate level phosphorylation Bio 93 Final Exam Section F 2012 - A Page 7 of 9 Student ID: __________________________ Name: __________________________ Short Answer Section Version A Answer concisely and accurately in the space provided. If your response contains both correct and incorrect information, it will be marked incorrect. 1. (2 pts) Earlier in the exam you were asked the following question: “The Drosophila oocyte extends microtubules into the nurse cells and dynein transports bicoid into the oocyte via dynein. Where are the minus ends of the microtubules? A. Oocytes, or B. Nurse cells?” In the space provided, explain your answer choice: 2. (2 pts) Excitatory neurons in the brain release the neurotransmitter glutamate, which binds to receptors on postsynaptic target cells. This action of glutamate is an example which type of cell signaling discussed in class? ________________________________ 3. (8 pts) The gene product for the glutamate receptor can be alternatively sliced to create a more sensitive binding site. Label the following diagram to match the book. A_________________________________ B_________________________________ C_________________________________ D_________________________________ 4. (2 pts) After synaptic release, glutamate molecules are removed from the synaptic cleft by a co-transporter that depends on an ionic gradient. Based on your knowledge of distribution of ions across the cell membrane, predict which ion travels down its gradient to transport glutamate back into the pre-synaptic cell: _________________________________ Bio 93 Final Exam Section F 2012 - A Page 8 of 9 5. (2 pts) Vesicles that contain newly synthesized glutamate receptors are transported to the axon terminals after processing. Where were the receptors processed? _________________________________ 6. Sea urchin eggs are placed in seawater at either normal sodium concentration or high sodium concentration. The eggs are then exposed to sea urchin sperm, and the membrane potential is measured. Below is shown the membrane potential at normal sodium concentration. a. (1 pt) Draw a line that shows the membrane potential in high sodium concentration. b. (2 pts) On the Y axis the numbers represent units of c. (2 pts) On the X axis the numbers represent units of _________________________________ _________________________________ 7. (2 pts) When the neurotransmitter serotonin binds to the postsynaptic membrane of a neuron it opens K+ channels. How will this affect the membrane potential ? _________________________________ This is the end of the exam. If you would like a scan of your short answer returned to you as a pdf via EEE, please fill out the Rapid Return form available at the front of the room. Bio 93 Final Exam Section F 2012 - A Page 9 of 9