Homework 11W.docx - CHEM 112 Name Dr. Jay Badenhoop...

nonpolar
side group (R)
N-terminal end
C-terminal end
peptide linkage
CHEM 112 Name __________________________________
Dr. Jay Badenhoop
Homework #11 (Chapter 22) (20 pts)
1. The covalent ( ester / amide / hydrocarbon / hydrogen ) bond between peptides is responsible for the
( primary / secondary / tertiary / quaternary ) structure of a protein. (Delete incorrect answers) (2 pts)
2. (a) Of the twenty amino acids, only _______ of them are termed essential amino acids. (1 pt)
(b) What does it mean when an amino acid is termed “essential”? (2 pts)
3. Draw an example of hydrogen bonding between the carbonyl group and the
secondary NH group of two different amino acids in the box. (2 pts)
4. Which type of attraction (hydrophobic interaction, H-bonding, ionic/ion bridge, covalent) might
occur between the side chains of the following pairs of amino acids? (3 pts)
(a) alanine and valine Attraction:
(b) serine and serine Attraction:
(c) cysteine and cysteine Attraction:
5. What defines a “complete” protein source? (2 pts)
6. In the tripeptide below, drag the labels on the right to circle the appropriate parts. Also drag the asterisks to
mark all chiral carbons. (4 pts)

H
3
N CH
CH
2
C
O
NH CH
CH
2
C
O