Explain what a van der Waals force is.  Match the atoms and molecules listed below with the appropriate descriptive. Choose from: 

Question 1

A

1. Explain what an ion is.
2. Explain what a van der Waals force is.
3. Match the atoms and molecules listed below with the appropriate descriptive. Choose from: 
4. Circle the “side chain” in each of the amino acids given below. 
5. Check the following terms to describe the side chains of the amino acids you circled above. 
6. Explain why ethane (C2H6) is a non-polar molecule while ethanol (C2H5 – OH) is a polar molecule. (A diagram of each molecule may help.)

B

1. What are two main differences between prokaryotic cells and eukaryotic cells?
2. Match the letter of the organelle on the left with the function or characteristic on the right. 

Question 2 

One day in lab while studying your favorite enzyme, Votase, you discover the following potential interactions that could occur between this amazing enzyme and its substrate of choice.

a) At each site between the chemical group on the substrate and the closest side chain of an amino acid on Votase determine if a favorable interaction is likely to take place. If a favorable interaction is likely to take place, give the name for the strongest direct intermolecular interaction. Choose from ionic interaction, covalent bond, hydrogen bond, and van der Waals force.

b) For all cases where a potential interaction seemed unfavorable, explain why.

Question 3 

a) In your continuing work with the enzyme votase you discover that the enzyme is also a transmembrane protein (part of the protein crosses the lipid bilayer of the cell). Circle the portion of the sequence below that you would expect to be the transmembrane region of the protein.

+NH3 – glu – trp – asp – arg – his – asp – phe – glu – ser – gly – pro – thr – phe – ile – trp – leu – ile – trp – leu – val – ile – ala – val – leu – phe – leu – leu – ile – trp – ala – val – leu – arg – pro – gly – cys – ser – lys – ala – tyr – ala – lys — val – cys – ala – gly – cys – ser – asp – lys – gly – glu – COOH 

b) Why will the section you circled be embedded in the membrane?

c) Draw a schematic of the phospholipid bilayer. Label the lipid hydrocarbon chains, phosphate hydrophilic heads, and water.

Question 4 

a) In the peptide below, circle the peptide bonds. What are the amino acids in this peptide?

b) What is the name of the macromolecule below? ________________

c) What is the chemical difference between the pentose sugar in DNA and the pentose sugar in RNA? (See page 48 in text book.)

STRUCTURES OF AMINO ACIDS at pH 7.0