. (1 points) What makes phospholipids good molecules for cell membranes? 2. (1 p
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Question
. (1 points) What makes phospholipids good molecules for cell membranes?
2. (1 points) List two differences between glucose and fructose.
3. (2 points) Based upon their chemical structures, what is the difference between saturated and unsaturated fats?
4. (2 points) List and explain two uses of proteins in your body.
5. (2 points) What are the basic structural units of proteins? Why is it important to consume enough protein in your diet?
6. (2 points) Explain why humans can digest starch but not cellulose.
7. (1 point) 20 different amino acids make up proteins. What makes one amino acid different from others?
8. (1 point) Which aspects of protein structure are stabilized by hydrogen bonds?
9. (1 point) Explain why a denatured protein no longer functions normally.
10. (2 points) Explain the phenomenon known as “hydrophobic interaction” that contributes to the tertiary structure of proteins. If a protein is taken out of water and put into a nonpolar liquid like oil, how would you expect the protein to rearrange itself?
Explanation / Answer
1. The cell membranes are made of “phospholipids” and they are major kind of lipids found in all biological membranes. As the name indicates, the phospholipid contains phosphate and fatty acid molecules in its structure. Cell membrane also contains proteins, lipids and carbohydrates in its structure.
The lipid end (fatty acid) of fatty acid is non polar (hydrophobic), and the phosphate attached alcohol serves as a polar head. In the structure of cell membrane, the outer and inner layers are exposed with these polar ends and the middle part contains lipid layer. Thus, the hydrophobic lipid layer is sand witched between two hydrophilic phosphate layers, so it is also called as “phospholipid bilayer (PLP, i.e. phosphate-lipid-phosphate)”.
Thus, due to the amphipathic nature (both polar and nonpolar) of phospholipids, they provide the nature of selectivity to the cell membrane, and are good candidates for cell membrane.
2. Both fructose and glucose are monosaccharides, but they have differences from chemical and physiological point of view.
a. The functional group in fructose is a ketone, where as fucntional group in glucose is aldehyde.
b. The melting point of fructose is 103oC, melting point of glucose is 150oC.
c. Unlike glucose, fructose has higher glycemic load, and lower glycemic index.
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