Sections B and D FIRST EXAM Sept 23, 2005

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1 BCOR 011 Exploring Biology NAME Sections B and D FIRST EXAM Sept 23, 2005 This exam consists of 17 MULTIPLE, multiple choice questions with 153 answer choices (each answer choice is worth 0.65 pt; 100 pts total yes, you get a free 0.55 pt), Choose ALL answers that you think are correct. There is NO SET NUMBER of correct answers for a question; for each question ALL or NONE of the choices may be correct. So carefully evaluate each answer choice on its own merit as a possible correct answer to complete the statement. Do not be misled by half-truth statements in which the answer is a true statement but has no relation to the question statement. Indicate your choice(s) by circling the number and writing the number in the left hand column. Please do both, so there is no doubt of your intention. If you believe NONE of the answers are correct, write none in the left hand column. If you think an answer or question is ambiguous, ask us to clarify it, or write a justification on the right hand side near your choice. A. Messenger Ribonucleic acid (mrna): 1. is a polymer comprised of ribonucleotides 2. is a polysaccharide 3. contains the nitrogenous bases uracil (U), cytosine C, Guanine (G), and Adenine (A) 4. is a polymer held together by phosphodiester linkages 5. is a polymer held together by peptide bonds 6. is an informational molecule in the cell 7. contains chiral carbons 8. is a polymer comprised of amino acids 9. has a primary sequence that contains the conceptual information directing how to build the primary sequence of a polypeptide 10. bears a negative charge at ph is labile (hydrolyzed of monomers) at ph 9 due to the reactivity of its 2 OH (hydroxyl) groups B. Triglycerides differ from one another by: 12. the chain length of their constituent fatty acids 13. whether they support the nomination of John Roberts 14. whether their constituent fatty acid chains are saturated or unsaturated whether their constituent fatty acid tails are nonpolar or polar 16. whether they are soluble in water or not 17. their constituents approval rating of George W. Bush 18. how many hydrogen bonds they can form 19. whether they can ionize in water at ph whether they are solids or liquids at room temperature 21. whether they have the bucks to afford a gallon of gas 1

2 C. You just bought a bottle of Creamy Italian Salad Dressing and note that the two most abundant ingredients are water and canola oil. You know that oil and water don t mix, yet after staring at the bottle for several hours you don t see them separate into two phases! What amphipathic molecules in the list of ingredients below keeps this salad dressing in one creamy phase? Ingredients: 22. water canola oil (a triglyceride) 24. corn oil (a triacylglycerol) 25. sodium palmitate (the ionized form of a free fatty acid associated with a Na + ion ) 26. lecithin (a phospholipid called phosphatidyl choline) 27. high fructose corn syrup (a carbohydrate monomer called fructose) 28. vinegar (a carboxylic acid with a pk a of 4.5 called acetic acid) 29. herbs 30. sodium benzoate (an antioxidant) D. If a substance has a carboxylic acid group with a pk a of 5, you can expect that : 31. it would prevent the price of gas from going over $5.00 per gallon 32. it is a good buffer at ph it contains a functional group that will be ionized at ph if the ph is near 5.0, this substance would absorb added H + ions to maintain the ph relatively constant 35. if the ph is near 5.0, this substance would absorb added - OH ions to maintain the ph relatively constant 36. if the ph is near 8.0, this substance would absorb OH ions to maintain the ph relatively constant 37. the substance would absorb any added acid or base, regardless of the ph 38. this substance contains at least one alcohol (R-OH) group 39. this substance contains at least five chiral ( handed or asymmetric) carbons 40. this substance has hydrophobic character when the H + ion concentration is 1x10-5 M 41. at ph 5, 50% of the substance is in the ionized form and 50% is in the molecular form E. The Phosphate functional group: 42. is a good buffer at ph always bears a negative charge in biological systems is the reason that gasoline costs $3.09 per gallon 45. can exist as either a hydrophobic or a hydrophilic species 46. is an example of an aromatic ring F. The forces holding DNA into its typical secondary structure include: 47. hydrogen bonding between the polar edges of the nitrogenous bases 48. hydrogen bonding between amino and carboxyl groups in the polypeptide backbone hydrophobic interactions between hydrophobic amino acid R-groups 50. FEMA 51. stacking of the hydrophobic nitrogenous bases on top of one another 52. disulfide bridges between cysteine residues. 53. ionic attraction between the negatively charged phosphate groups on the sugar-phosphate 2 backbone with one another 54. earthen levies 55. the amphipathic nature of the fatty acid tails

3 BMB 280 Introduction to Molecular and Cellular Biology NAME G. The molecule pictured at right : 56. is an amino acid 57. contains a chiral carbon is a nucleic acid monomer 59. is a triglyceride 60. contains a hydrophobic R-group 61. is one of the monomers used to build polypeptides 62. is the outrageously expensive form of gasoline 63. is the ionized form of a free fatty acid 64. is one form of a triose (monosaccharide) 65. was built 10 feet below sea level H. The plasma membrane of an animal (Eukaryotic) cell: 66. principally consists of a phospholipid bilayer 67. has peripheral membrane proteins loosely associated with phospholipid head groups A L L I. True monosaccharides differ from one another by: 76. the price per gallon they are willing to pay for gasoline 77. the number of carbon atoms they contain contains carbohydrate polymers attached to the extracellular surface of membrane glycoproteins 69. contains carbohydrate polymers attached to the extracellular surface of membrane glycolipids 70. contains integral membrane proteins with α-helical segments that project a surface of hydrophobic R-groups into the membrane interior 71. contains cholesterol to maintain proper fluidity 72. lets nonpolar molecules like oxygen enter into the cell by simple diffusion 73. selectively lets ions into the cell through specific channel proteins by facilitated diffusion 74. pumps Na + ions out of the cell by an active transport process 75. uses indirect active transport to accumulate glucose in the cell against its concentration gradient 78. the number of sulfur atoms they contain. 79. whether they are in the premium or regular form 80. whether they are D-form or L-form isomers 81. their ability to price gouge 82. the number of carbon-carbon double bonds they contain J. The carbohydrate monomer pictured to the right has: 83. a carbonyl at the # 1 carbon 84. a chiral carbon at the # 2 carbon a hydroxyl group at the # 3 carbon 86. a sulfhydryl group at the # 4 carbon 87. the ability to circularize into a ring with α- and β- forms 88. a chiral carbon at the #6 carbon 89. been nominated to sit on the supreme court 3

4 BMB 280 Introduction to Molecular and Cellular Biology NAME K. Which of the following are amino acids with hydrophobic R-groups: 90. ophelia 91. gasoline ` 92. phenylalanine 93. methionine 94. leucine 95. rita 96. isoleucine 97. aspartic acid 98. glutamic acid 99. katrina 100. β-d-glucose 101. alanine L. The structure at right: 102. is an alpha (α) helix 103. is a beta (β) sheet is a double helix 105. is a secondary structure of a polypeptide 106. is a tertiary structure of a polynucleotide 107. is a phospholipid 108. is a carbohydrate polymer 109. will bind lipids within the hydrophobic center of the structure 110. thinks FEMA should have responded faster 111. is a micelle M. You have obtained the graph below by incubating various concentrations of a substance with a biological membrane. This graph indicates this substance passes through the membrane: against its concentration gradient 113. by simple diffusion 114. by facilitated diffusion 115. by osmosis 116. through a carrier protein in the membrane 117. faster than George W. Bush responds in a crisis Rate of transport Concentration substance 4

5 BMB 280 Introduction to Molecular and Cellular Biology NAME N. Which of the following forces stabilize protein tertiary structure: 118. hydrogen bonding between polar R-groups on the surface of secondary structures 119. glycosidic bonds between amino acid monomers hydrophobic interactions between R-groups on the surface of secondary structures 121. the senate judiciary committee 122. disulfide bonds between cysteine residues 123. OPEC 124. electrostatic interactions between positively and negatively charged R-groups 125. the strategic oil reserve 126. hydrogen bonding of A with T and G with C 127. the National Guard 128. phosphodiester bonds between R-groups on the surface of secondary structures O. Familiarity with the properties of water is important to understand: 129. why polymers adopt the secondary and tertiary structures they do why gasoline has gotten so expensive 131. why some hydronium (H + ) ions and hydroxide ( - OH) ions are always present for reactions in water 132. why hydrophilic polymers tend to hydrogen bond with themselves rather than water 133. how Frodo failed and Bush got the Ring 134. why you can skate on ice 135. why temperature on earth does not fluctuate wildly P. The Rough Endoplasmic Reticulum (RER): 136. is where proteins are synthesized that are destined to be secreted out of the Eukaryotic cell is where integral membrane proteins are synthesized in Eukaryotes 138. is where short polysaccharide chains are added to newly synthesized proteins 139. is where proteins are sorted to go to the lysosome 140. is where ribosomal RNA is made and ribosomes are assembled 141. contains the heterochromatin, where mrna is made 142. is the energy powerhouse of the animal cell 143. is the site of nucleotide synthesis in Prokaryotic cells 144. is an organelle of Eukaryotes bounded by a membrane Q. Chiral carbons: are found in polysaccharides 146. are found in L-amino acids 147. are found in polypeptides 148. were found in John Robert s legal briefs 149. are found in saturated free fatty acids 150. are found in water molecules 151 are found in DNA 152. have 4 different functional groups attached to them 153. are found in α-d-glucose 5

6 Number wrong x 0.65 Points off GRADE 6