Case Study: The Skeletal System

Questions
1. What do lipids have in common?
All lipids are hydrophobic, which means they are insoluble in water (Tamarkin, 2011).

2. Describe the molecular structure of saturated and unsaturated fatty acids.
The molecular structure of saturated fatty acids consists of single bonds connected to each carbon, which results in a maximum amount of hydrogen atoms on the molecule. The molecular structure of unsaturated fatty acids consists of single and double bonds connected to its carbon atoms. This results in fewer hydrogen atoms due to the double bonding (Chen and Jayant).

3. Compare the structures and melting points of saturated, monounsaturated and polyunsaturated fatty acids with the same number of carbon atoms.
Saturated fatty acids have a higher melting point because its structure contains single bonds with each carbon, which results in a maximum number of hydrogen atoms. The more hydrogen atoms, the higher the melting point. Polyunsaturated fatty acids have a lower melting point then monounsaturated fatty acids because polyunsaturated fatty acids have two or more double bonds within its carbon structure. Monounsaturated fatty acids only have one double bond contained in its structure. Because polyunsaturated fatty acids have two or more double bonds, it contains less hydrogen atoms connected to the molecule, resulting in a lower melting point then monounsaturated fatty acids. The lower amount of hydrogen atoms in the molecule, the lower the melting point (Chen and Jayant).

4. Describe the difference of cis- and trans-arrangements.
In a cis- arrangement, two hydrocarbon chains are on one side of the double bond, and two hydrogen atoms are found on the opposite side of the double bond (Chen and Jayant). I like to think that the hydrocarbon chains create a “C” shape from the double bond. “C” equals cis! In a trans- arrangement, two hydrocarbon chains are on opposite sides of the double bond, as well as the hydrogens (Chen and Jayant). I like to think that the hydrocarbon chains create an “S” shape along the double bond.

5. Compare the melting points of cis- and trans-fatty acids isomers.
Trans-fatty acids are more saturated because their structure has less resistance to bend, resulting in a higher melting point then cis-fatty acids. Cis- fatty acids are more flexible to bend, which means they are less saturated and have lower melting points (Chen and Jayant). 6. Why have artificial trans fats been banned from New York city’s restaurants by the New York Health Department since July 2008?
Trans fats have been banned because they can be a huge hazard to our body resulting in clogged arteries. Trans fats are believed to be harmful because they contribute to heart disease by raising bad cholesterol and lowering good cholesterol at the same time (msnbc.com, 2006). Bad cholesterol is transported from the liver to the tissues, which leads to clogging in the blood vessels (Chen and Jayant).

7. Briefly explain why Dolly has to shake the salad dressing, a mixture of olive oil and vinegar, before pouring it onto her salad.
Both oils have different polarities which means they don’t like to stay mix. Before pouring this mixture on salad, Dolly has to shake it up vigorously until most of it is mixed to pour on the salad or else the oils won’t be evenly dispersed and will remain separated.

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