ps8a[1] - MCB 100 Fall, 2002 Problem Set 04, September 4...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
MCB 100 Fall, 2002 Problem Set 04, September 4 Q1. Titration of valine by a strong base, e.g., NaOH, results in two pKs (pK1 and pK2). Which of the following reactions describes the titration reaction occurring at pK2 (pK2=9.62)? A) -COOH +OH - -COO - +H2O B) -COOH + -NH 2 -COO - + -NH 2 + C) -COO - + -NH 2 + -COOH + -NH 2 D) -NH 3 + + OH - -NH 2 + H 2 O E) -NH 2 + OH - -NH - + H 2 O The amino group will get deprotonated. Answer = D Q2. At the isoelectric pH of a tetrapeptide, which of the following statements are true? A) the amino and carboxyl termini are not charged B) the internal amino acids of the tetrapeptide cannot have ionizable R groups C) the total net charge is zero D) there are four ionic charges E) only the amino and carboxyl termini can contribute charge Answer: (C) The total net charge is zero at the isoelectric pH. Q3. In a mixture of five proteins listed below, which should elute second in size- exclusion (gel filtration) chromatography? A) cytochrome c, M r = 13,000 B) immunoglobulin G, M r =145,000 C) ribonuclease A, M r = 13,700 D) RNA Polymerase, M r =450,000 E) serum albumin, M r =68,500 In gel filtration chromatography, larger molecules elute first. The answer is (B) – immunoglobulin G. Q4. (i) By adding SDS (sodium dodecyl sulfate) during the electrophoresis of proteins, it is possible to do which of the following? A) determine the amino acid composition of the protein. B) preserve the protein’s native structure C) determine a protein’s isoelectric point D) separate proteins primarily on the basis of molecular weight E) determine an enzyme’s specific activity
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
(ii) If gel electrophoresis were to be carried out without SDS, what complications might arise? Answer:
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 04/12/2008 for the course MCB 100 taught by Professor Berger during the Fall '04 term at University of California, Berkeley.

Page1 / 4

ps8a[1] - MCB 100 Fall, 2002 Problem Set 04, September 4...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online