exam_1S

Exam_1S - Solutions for 7.012 Quiz I Class Ave = 83 Standard Dev = 12 Approximate grade A B C D F Range 90 100 78 89 60 77 48 59 0 47 34 38 23 3 2

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Solutions for 7.012 Quiz I Class Ave = 83 Standard Dev = 12 Approximate grade Range % A 90 - 100 34% B 78 - 89 38% C 60 - 77 23% D 48 – 59 3% F 0 – 47 2%
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2 Question 1 (29 points) a) To the right is an iconic view of a phospholipid molecule. List the atoms that are found in the shaded region of this molecule. Describe the properties associated with this region. C and H. These two atoms form non-polar covalent bonds and this region is very hydrophobic. List two atoms that are found in the boxed region BUT NOT in the shaded region of this molecule. Describe the properties associated with this region. O, P or N. These atoms form polar covalent bonds and this region is hydrophilic. . Phospholipids can arrange in the form of a lipid bilayer, which is the basis of the cell membrane. The membrane has many embedded proteins. List three amino acids whose side chains could be exposed to the part of the membrane formed by the shaded regions of the phospholipids. Note that a chart of the amino acids is found on the final page of this exam. Ala, gly, ile, leu, met, phe, pro, trp, or val b) Below are two molecules that have the same chemical formula: C12H22O11. i) Each of these molecules could be described as… (circle all that apply): a monosaccharide an amino acid a nucleotide ii) Prototrophs can use these molecules as the only carbon source in minimal media. The prototrophs use these molecules as… (circle all that apply): a monomer (building block) of DNA a monomer (building block) of protein c) These two molecules have the same chemical formula and a 1-4 glycosidic linkage. Enzyme X can cleave bond 1 but not bond 2. Explain why enzyme X specifically cleaves bond 1 but not bond 2. The stereochemistry of these two molecules is different, which means that they have different shape. Each enzyme has a binding pocket that is exquisitely specific for its substrate, thus the binding pocket of enzyme 1 will not accommodate the molecule on the left. Bond 1 Bond 2
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3 Question 1, continued Below is the structure of ATP. d) On your drawing above… label the 1’, the 3’ and the 5’ carbons. circle the bond that is broken when this monomer is added to a growing RNA polymer.
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This note was uploaded on 03/12/2011 for the course BIO 7.012 taught by Professor Lander during the Fall '10 term at MIT.

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Exam_1S - Solutions for 7.012 Quiz I Class Ave = 83 Standard Dev = 12 Approximate grade A B C D F Range 90 100 78 89 60 77 48 59 0 47 34 38 23 3 2

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