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Write out the un-ionized structure of valine & phnylalanine. Do either have enantiomers?

Write the zwitterion structures of both.

Show what happens if it becomes more acidic.

Write structure for phe-val (ionized or unionized). Is it the same as val-phe? Why?

Would the dipeptide be neutral, acidic, or basic? Why?

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Solution Preview

I have attached a powerpoint presentation dealing with amino acids. Un-ionized basically means they don't have charges floating around. See slide 11 for the difference between un-ionized and ...

Solution Summary

125 word solution as well as an attached 15-page Powerpoint presentation on amino acid classifications.

See Also This Related BrainMass Solution

Assorted Organic, Bio-Organic Chemistry Problems

Please see the attached file for the complete problems.

1) Label each pair of stereoisomers below as:
a) enantiomers b) diastereomers c) identical

2) Convert the following Fischer projections into a tetrahedral representation, and assign R or S stereochemistry to each.

3) The reaction below is an example of:

a. nucleophilic addition
b. electrophilic addition
c. nucleophilic acyl substitution
d. electrophilic subsitition

4) Refer to the data below to answer the following questions:

Amino Acid Isoelectric point
Arginine 10.76
Glutamic Acid 3.22
Tryptophan 5.89

The most basic amino acid is ____
The most acidic amino acid is ___

5) MATCH a structure from the list below to each of the following terms. Place the letter of the structure in the blank to the left of the term which it describes.

___ an octapeptide
___ an amino acid in its zwitterionic form
___ a polypeptide which gives four fragments on treatment with chymotrypsin
___ a carboxyl-protected amino acid
___ a peptide coupling reagent
___ small organic molecules which act as coenzymes

6) MATCH each of the following terms to a structure from the list below. There is only one correct structure for each term, and structures may be used more than once. Place the letter of the structure in the blank to the left of the corresponding term.

_________ a phosphoglyceride
_________ monoterpene precursor
_________ a triglyceride
_________ a sphingolipid
_________ a soap
_________ a steroid
_________ a sesquiterpene

8) Choose a structure from the list provided below that best fits each of the following descriptions. Place the letter of the structure in the blank to the left of the description. There is only one correct answer for each question.

a. starch
b. cellulose



f. sucrose

___ a monosaccharide that give a negative benedict's test
___ -D-glucopyranose in a Haworth projection
___ a disaccharide

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