CHEM-237-1059-Quiz1_exam

CHEM-237-1059-Quiz1_exam -...

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Unformatted text preview: Chemtstrgll'lflniza‘l- (10111119132005 , , ,, _____ 7, , , Mark [3 /35 Name :% Student number: * Section A: Answer the following multiple choice questions (11 marks). 1. How many hydrogen bonds can a water molecule potentially take part in forming? / A) one B) two C) three Q) four E) none of the above 2. Rank the following in terms of strength, from greatest to lowest: A) covalent bonds, hydrogen bonds, ionic interactions )Q B) covalent bonds, ionic interactions, hydrogen bonds ©‘ ionic interactions, covalent bonds, hydrogen bonds D) hydrogen bonds, covalent bonds, ionic interactions E) none of the above 3. Which of the following are typical hydrogen bond interactions? / A) N—H, H—H, S——H, Na—Cl B) O—H, S—H, Fe—H (CW—H, O—H, S—H D) N—H, S—H, Na——CI E) none of the above 4. In a neutral aqueous solution the concentrations of H+ and OH' are each: A). 55 M (B) 1 x 10“7 M C) 1 x 10““ M D) 5 mM E) none of the above 5. What is the final . when 100 mL of 0.5 M HCl is added to 900 mL of water? ./ A‘ - 1.3 B) 5.0 C) 13.0 D) 0.5 E) none of the above 6. Which of the following statements is true? _/ A) Buffers work best when the pH is within 3 units of the pK. B) Buffers can be prepared using the Henderson—Hasselbalch equation. C) A buffer requires a combination of a weak acid and its conjugate base. D A and B B and C j A solution of volume 0.300 L contains 3.4 g of a dissolved pure protein. If the molar mass of the protein is 31,000 g/mol, what is the osmotic pressure of the solution at 30°C? Given that the gas constant is 0.0821 L atm "K" mol". A 0.00090 atm 0.0058 atm 0.92 atm B. C. D. 0.092 atrn‘ @I 0.0091atm ‘ Most amino acids have a chiral center. (i) Name (full name, 3 letter code, single letter code) and draw the chemical structures-of the :two, amino - -- acids that have M carbon chiral centers. Identify the two chiral carbons in your structures. (ii) Name (full name, 3 letter code, single letter code) and draw the chemical structure of the only amino acid that does n_0t have a chiral center. Question D: (5 marks) q/ Draw the two chemical structures of the paired bases proposed by Watson and Crick in their model for double stranded DNA. Identify each of the bases in your answer. \/ o , /’ til“ 2 It ‘ ' /C / ¢C ‘\ C 8. Erwin Chargaff studied DNA sfiUc—turea’ndflc’omwpositi—OTWhafobservation(s) didhefi make? ' A) Nucleotides are not all present in the same amount. ' X; - . ' B)» «Nucleotide composition varies. amongspecies. : ; .r 1.» 1'5? , : » ' ,C)__ The ratios of A to T and of G to C are both lzl. (REA and C E) A, B, and C 9. The linkage between nucleotides is a: A) peptide linkage / g?) phosphodiester bond ’ amide bond D) all of the above E) none of the above 10. Which of the following statements is (are) true about restriction endonucleases? _/ A) They typically recognize and cleave palindromic sequences. B) Their natural function in bacteria is to cleave foreign DNA. 9)» They are used to reproducibly break up large pieces of DNA into discrete fragments. D) 7 all of the above none of the above ll. To 125 ml of0.lOO M HA is added 40.0 ml of 0.200 M KOH. Ifthe pKa of HA is 6.73, what is the pH ofthis solution? H25. X P“: c 7:: t (ajfiMAL‘cIF—IR A. 7. 1 7 [kofilléggé '5 B. 6.48 C. 6.98 (1:: 6.54 E. 6.73 Question B: (6 marks) Based upon your knowledge of the chemical structure of amino acids, match the amino acids in the left column with the appropriate side chain types in the right column. ’(a) Lys _6_ ( 1) nonpolar aliphatic 7b) Glu i (2) nonpolar aromatic 1c) Leu _l_ (3) basic ’(d) Cysé: (4) acidic (6) Tip 2; (5) sulfur-containing ’(‘0 Ser ._H__ (6) hidroxyl—containing 27., 'i ,4 QE§$F§9nPil7 marks) , Your boss asks you to prepare a pH 9.00 glycine buffer. ’ ‘ ' ' (p’K; values for glycine are 2.35 andi9.78) a) Write out the equilibrium equation (including their chemical structures) for the required conjugate acid/ base pair of glycine. b) Your boss provides you with glycine hydrochloride (C2N02H6Cl, Formula weight 93.0 g mol'l) and 5.00 M HCl and 5.00 M NaOH stock solutions. Give a recipe for preparing 0.50L of 200' mM pH 9.00 glycine buffer. Ovllw ca ch Q C K v (‘jcc ( ‘ _ >4. , __—\ fl «“3 uwc'eu We: 1+ 61"” H V" “ Ly 'l ’4. :\ l ti .1? NH b3 Cl; [luvllmlfi [(21402 Ht, (18¢ 9 2 M ’ lL o k...‘_4 Pli' pkc l J C >6 c “6‘ ’15 — cam; \ :9" 7' l CINOZH L\ C L "LL: ) C n r“ 3.7 r _ 0; _fl _f 7 _ ‘ _ V 7 IV“ _ 7‘ 1 4' h”? "E: r) "lcfimuzuefl : Odo wix 3349‘ “find" 1 éLB 3 to? a 1%, (,1: r; R Li. [6? iNSO) Cb -.-.. Ccrccwz) 7 LLchql __ CB +- Ca = 63-1 M - _ ,1 D O ,J-agé C; + C.“ a (3-. ~20 M C:\ t: C-7. kl : 0 4’1 M ‘ 9/ ,‘f and. 4‘ (>03 moi ‘ (2.3L: O'C3l8 mc\ nCG: Q. m [316ng 0,31 : ongS' mql , r _E a. ~"r ,I lac?”- :70 meal (9“th + acéxlmo‘ luv—LOW: r” l“ "m N‘ :‘> \lvao‘dr : (Sr-GHME‘>“X ©‘i‘88rmol = O-G'E7 L l :- 37 mL . . r ‘ - ’3 l0 "1‘ ‘ :> " ‘ A: ‘V lent “range (Lilict L1: flxgy a 3 a CZ “302 Fig, C \ cmCl '37 m L A‘ C H ' mm L) ’ Al \ vo \Uwéf «is 0’ ‘ 39 L L6 (:51?va LU eJ‘e y . / ...
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