101 GSCI Spring 2003 Name: _______________________________ JMU ID Number: ____________________________ Quiz #7: Secondary Bonding
Dr. B. Augustine
1. Adenine (A)-Thymine (T) and Cytosine (C)-Guanine (G) are called complimentary base pairs in the production of DNA. Briefly explain why these only bond with each other. A-T and C-G both bond through hydrogen bonds. They are exactly complimentary in that A-T has two hydrogen bonds and C-G has three hydrogen bonds at the correct distances and the correct angles. This leads to the famous double helix geometry of the DNA molecule. The hydrogen bonds are what unzip during DNA replication by RNA
2. The following forces holding atoms together are arranged alphabetically. Divide these into primary and secondary forces and within these, arrange them from strongest to weakest. Covalent, Hydrogen bonds, Ionic, Metallic, van der Waals
Primary
Ionic
Secondary
Hydrogen bonds
Covalent
Van der Waals
Metallic
GSCI 101 Spring 2003
Dr. B. Augustine
3. What is the primary reason that soap is useful for dissolving greasy in stains water? (Be briefyou do not need to describe the process, just the reason why soap is unique.) Soap is designed with both a polar and a nonpolar group on the same molecule. This enables nonpolar grease to be dissolved in polar water.
4. Which of the following classes of materials exhibits both primary and secondary bonding? a. b. c. d. e. Polymers Ceramics Semiconductors Metals Glasses
5. Poly vinyl chloride (PVC) is used in items such as plastic pipes for plumbing. Polyethlyene (PE) is a plastic used for things like plastic bags. The monomer for PVC is CHCl- and the monomer for PE is CH2-. Briefly explain why is PVC so much ...