7.012: Introductory Biology-Fall 2004 Instructors: Professor Eric Lander, Professor Robert A Weinberg, Dr. Claudette Gardel 7.012 Quiz 1 Answers A287 25% of test takers B273 w34% of test takers C260 24.3% of test takers D≥50 w10.1% of test takers F249 6.5% of test taker Regrade requests (with a note attached indicating the problem and part you want looked at) Monday 10/04/04 Question Value Score 16 2 20 3 16 16 5 15 6 17 100
7.012 Quiz 1 Answers A≥87 ~25% of test takers B≥73 ~34% of test takers C≥60 ~24.3% of test takers D≥50 ~10.1% of test takers F≥49 ~6.5% of test takers Regrade requests (with a note attached indicating the problem and part you want looked at) Monday 10/04/04 Question Value Score 1 16 2 20 3 16 4 16 5 15 6 17 100 MIT Biology Department 7.012: Introductory Biology - Fall 2004 Instructors: Professor Eric Lander, Professor Robert A. Weinberg, Dr. Claudette Gardel��
Question 1 a)Match each boxed chemical interaction in the structures below with the appropriate description. 10 pts van der Waals interaction phosphodiester bond hydrogen H H H CH CHa OH -H NH H OH A B 0-P=0 OH
Question 1 a) Match each boxed chemical interaction in the structures below with the appropriate description. 10 pts _____B_____ peptide bond _______E___ ionic bond ____A_____ van der Waal’s interaction ______D____ phosphodiester bond _____C_____ hydrogen bond C A B D E 2
b)Which one of the following structural features is NOT based on hydrogen bonds? Circle all that apply. 3 pts i) complementary base pairing in DNA 1) protein primary structure i)protein secondary structure iv)complementary base pairing in RNA c)your friend tried to remove some writing on a plastic box. He used a napkin dampened with water, which did not work. Then as you advised, he used ethanol (instead of water) and successfully removed the writing. Circle why ethanol was better than water in this case3 pts [formula of ethanol: CH3-CH2-OH] i)Ethanol has a greater surface tension, so it extracts the ink molecules better from the plastic i Ethanol can form hydrogen bonds with the ink molecules iii One end of ethanol is non polar this makes ethanol a better solvent for the ink molech iv)Ethanol is more hydrophilic, so it washes off the writing more efficiently
Name________________________________ b) Which one of the following structural features is NOT based on hydrogen bonds? Circle all that apply. 3 pts i) complementary base pairing in DNA ii) protein primary structure iii) protein secondary structure iv) complementary base pairing in RNA c) Your friend tried to remove some writing on a plastic box. He used a napkin dampened with water, which did not work. Then as you advised, he used ethanol (instead of water), and successfully removed the writing. Circle why ethanol was better than water in this case. 3 pts [formula of ethanol: CH3-CH2-OH] i) Ethanol has a greater surface tension, so it extracts the ink molecules better from the plastic. ii) Ethanol can form hydrogen bonds with the ink molecules. iii) One end of ethanol is non-polar. This makes ethanol a better solvent for the ink molecules. iv) Ethanol is more hydrophilic, so it washes off the writing more efficiently. 3
Question 2 a) Fill in the percentages. If the value can' t be determined write ND". 6 points 1) According to Chargaffs rule, if the dna content of a cell was composed of 15% a then C would make up %o, G would make up__35_%, and T would make up__15% of the cell's DNA i)If the rna content of a cell was composed of 15%A, then C would make up ND_-%,G would make up_ND__%, and T would make 0% of the cells dna b)Match the following with all that apply. 6 points A. Lowers the activation energy of a reaction Lactase B. Raises the activation energy of a reaction C. Breaks down milk sugar to galactose and glucose ribozyme D. Lipid E. Protei The Transforming principle" F. DNA G. RNA c)Fill in the blanks. 2 pts each i)DNA is synthesized in the direction. Circle one C→N 3÷5 O→P N→C 5÷3 P→O ii Proteins are synthesized in the direction. Circle onel CN 3÷5 o→PN>C5÷3 P→O d Which of the following is used to make deoxyribonucleic acid? circle all that pply 4 points HOH, CH,OH O
Question 2 a) Fill in the percentages. If the value can’t be determined write “ND”. 6 points i) According to Chargaff’s rule, if the DNA content of a cell was composed of 15% A, then C would make up ____35______% , G would make up ___35______%, and T would make up____15%_______ % of the cell’s DNA. ii) If the RNA content of a cell was composed of 15% A, then C would make up ____ND______%, G would make up ____ND_____%, and T would make up____0%_______ % of the cell’s DNA. b) Match the following with all that apply. 6 points A. Lowers the activation energy of a reaction ___ace___ Lactase B. Raises the activation energy of a reaction C. Breaks down milk sugar to galactose and glucose ____ag___ ribozyme D. Lipid E. Protein ___f______ “TheTransforming Principle” F. DNA G. RNA c) Fill in the blanks. 2 pts each i) DNA is synthesized in the _________ direction. Circle one. CN 3’5’ OP NC 5’3’ PO ii) Proteins are synthesized in the _________ direction. Circle onel. . CN 3’5’ OP NC 5’3’ PO d) Which of the following is used to make deoxyribonucleic acid? Circle all that apply.4 points H N OH H 4
Question 3 Eukaryotes have proteins called histones that are involved in tightly packing DNA. Below is a schematic of the interaction between a molecule of dna and the surface of a histone protein. X"represents an amino acid side chain sticking out from the surface of the protein towards the DNA backbone X Figure by MIT Oc a)Circle the type(s)of amino acids you would expect to find with side chains in the positions marked"? negative non-polar tively hydrophobic chargea charge d b)Circle the strongest interaction between the dna backbone and the histone protein van der Waals X-linked 2 pts
x x x Name________________________________ Question 3 Eukaryotes have proteins called histones that are involved in tightly packing DNA. Below is a schematic of the interaction between a molecule of DNA and the surface of a histone protein. “X” represents an amino acid side chain sticking out from the surface of the protein towards the DNA backbone. x x x x x x Figure by MIT OCW. a) Circle the type(s) of amino acids you would expect to find with side chains in the positions marked “X”? negatively non-polar positively hydrophobic charged charged 2 pts. b) Circle the strongest interaction between the DNA backbone and the histone protein. hydrogen ionic van der Waals X-linked 2 pts 5