You will have read that proteins are polypeptides composed of large numbers of amino acids linked together. The diagrams below show two peptides (small number of amino acids joined together). What...

You will have read that proteins are polypeptides composed of large numbers of amino acids linked together.

 The diagrams below show two peptides (small number of amino acids joined together). What functional groups do these peptides contain?

 

 
 
 
 
 
 
 
 
 

Expert Answers
hart379 eNotes educator| Certified Educator

The diagrams contain the following functional groups: amine, carboxylic acid, amine, and benzene ring.

The diagrams do not contain: alkene, ether, alcohol, amide, ester, or ketone. 

Alkene means there is a double bond on the parent chain and there is not.  All of the double bonds are part of functional groups.  An ether is an oxygen single bonded to two carbons and all the of oxygens in the diagram are double bonded to carbons with the exception of one of the oxygens in the carboxylic acid group.  The carboxylic acid is located at the far right end of the second diagram.  Alcohols are an -OH group bonded to a carbon, but can be eliminated from the answer choices because the only -OH group is part of the carboxylic acid and it cannot be two different functional groups at the same time.  There is an amide group in structure two.  The amines are found in the first diagram. There are no ketones or esters because all of the double bonded oxygens are already accounted for (in the carboxylic acid, the amide and the amines).

jenny101 | Student

See the following diagram, for the above question: http://img109.imageshack.us/img109/3273/proteinq2.jpg