General Chemistry

Practice Problems


Questions on Molecular Representations

  • Which representation described in the tutorial would you use to get the most accurate picture of the overall shape and approximate volume of the ferritin protein?
  • Which representation described in the tutorial would you use to see what atoms are connected together in a particular region of the ferritin protein?

(help)


Questions on Protein Structure

  • The two-dimensional (ChemDraw) structure of the amino acid phenylalanine is shown below. Indicate which part of this structure represents the amino acid's side chain.

    Random Unnamed amino Acid with Benzene Ring (help)
  • A segment of a protein is analyzed and found to contain the amino-acid sequence Glu-Leu-Asp. The ChemDraw structures of these three amino acids are in Figures 13 and 15.
  1. Draw a two-dimensional sketch (Lewis structure) of this section, showing the peptide bonds (like Figure 4).
  2. Draw a two-dimensional sketch (Lewis structure) of this section, showing the backbone of the amino-acid sequence (like Figure 5).

(help)


Questions on Release of Iron from Ferritin

  •  The two-dimensional (ChemDraw) structures of three amino acids are shown below. For each amino acid, tell whether it is polar or nonpolar. HINT: Remember that the polarity of an amino acid is considered to depend only on its side chain, because the other groups of amino acids become incorporated into peptide bonds forming the backbone of a peptide. The amino acids are not all shown in the same orientation, so you will need to determine which part of each amino acid is the side chain.
  1. Isoleucine (Ile)
    Isoleucine
  2. Phenylalanine (Phe)

    Phenylalanine
  3. Lysine (Lys)

    Lysine

(help)

  • If these three residues formed part of a channel, would the channel permit, Fe2+ to pass through it?  Explain your reasoning. (help)

 


Questions or comments can be directed to: chemistry@wustl.edu
This page created by Matt Traverso, Washington University in St Louis.
© 2004, Washington University.
Materials and Information present may be reproduced for educational purposes only.

Revised: 2004-08-08