The antidepressant medication Celexa is a racemic mixture of two stereoisomers, but only (S)-citalopram has the therapeutic effect. A stereochemically pure preparation of (S)-citalopram is sold under the trade name Lexapro. Which is true about the medications?

You have joined the Wee lab as an undergraduate student. This lab’s expertise is in protein engineering. You are tasked with purifying proteins for the research group.  The protein is a DNA polymerase (which binds negatively charged DNA) from a thermophilic organism (Pseudomonas furiosis). Your colleague has cloned this gene in the bacteria E. coli. Because the enzyme’s activity is negatively impacted by the addition of affinity tags, no tag was added to the gene recombinantly expressed.  Your goal is to purify this protein to a high degree of purify (>95%). But, you are challenged to purify your assigned protein in no more than two steps.  In your lab, you have access to the following chromatography techniques and columns.  Cation exchange chromatography Anion exchange chromatography Protein A chromatography Immobilized metal affinity chromatography Amylose resin Sepharose B resin Hydrophobic interaction chromatography Size exclusion chromatography Heat treatment Ammonium sulfate precipitation Your response to this question may take the following format.  For step 1, I will choose method X. Method X separates between based on property A. I chose method X because ….. For step 2, I will choose method Y Method Y separates proteins based on property B. I chose method Y because….  If you used a chromatography column in steps 1 and/or 2, you must specify how you will operate the column to retrieve (elute) your protein (increasing or decreasing salt gradient, pH adjustment, molecule addition). 

A peptide has the sequence Gln-His-Ser-Glu-Gly-Arg-Met Hint: Gln is glutamine.  Calculate the net charge of the molecule at pH 3.  Show how you arrived at the answer. 

Calculate the pH of a solution of a weak acid called MOPS in which 80 percent of the solute is in its weak acid form and 20 percent of the solute is in its weak base form. The pKa for MOPS is 7.2.  (show your work by typing in the essay box)

Match each description to the corresponding organelle. 

This question relates to DNA transcription. Match whether the described DNA transcription process is found in eukaryotes. prokaryotes, or both. 

Reasons students are asked to take courses that fall under the Liberal Arts include all of the following EXCEPT:

Explain the experience of the African slave and the indentured servant that ultimately ended up in the American colonies int he early colonial period (trace his/her experience beginning in Africa or Britain). Be sure to explain how slavery and servitude was introduced to colonial America, and the economic forces that drove it both in the colonies and abroad.

What is the output of the print statement a = 10b = 20c = 40d = “Howdy”print (2*(d) + (d))

Legal aspects of patient care are very important and must be followed AT ALL TIMES