Biochemistry Question Cross-Check! I\'ve answered these but would like them to b

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Biochemistry Question Cross-Check! I've answered these but would like them to be cross-checked. This is an old exam that I already submitted and earned a grade for. I'm using it as studying material for my comprehensive final.

15, A zwitter ion has a. a charge of +2 b et charge d. a charge of 1 e none what will be the char of a. 16 the y e, none 17. what will at pH be the charge of C. +2 the glutamic acid at 4.25) 3 (pKa e, none 18 (T F they occur as monopolar ions 19. amino dissolved in water When Structural difference(s) between aming acids are e. none. a. OH group b. s Y and F d. CH2 group 20 Characteristic(s) H2 group are of amino acids water most are solids with high include soluble in e, in the meting points b most are c all of configuration only b and the above are characteristics of Aa's 21. The pl for lysine (pKa 12.48) is approximately a. 5.6 e. 14 0.6 c. 7.8 rka 12 Consider the following oligopeptide QUESTIONS 22-25 Tyrosine R group pKa 10.5 pKa of o amino group 9.5 pKa of carboxyl group -2.2 22. What is the charge of peptide at pH-1 the c. 0 a. 2 23. What is the charge ofthe peptide at 2 b. +1 PKA neutral tide pH at 24. What is the charge of the pan e, -3 debe completely neutral peptide will be charged at pH's e. none all the pepti 25. t what pH wi dic b. a. basic

Explanation / Answer

Q15.

Zwitter ion has no charge, since it has, by definition, neutral charge

so no net charge, choose C

Q16

pH = 1, means plenty of H+ ions

so

expect COOH to form COOH and NH2 amino group to form NH3+ then this is +1

Q17

since pH is hihg, this is low in H+

so

NH3+ = NH2 + H+

and

COOH = COO- + H+

therefore, this is negative

Q18

TRuea, they are typically +1 or -1 chargefd in water

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