Napoleon's Buttons Chapter 6 - Silk

Napoleon's Buttons Chapter 6 - Silk

1. What chemically is a peptide bond?

The peptide bond is a bond between the resulting amide groups when two amino acids join at an "N-terminus" with a "C-terminus"

2.

What makes amino acids able to polymerize?

Amino acids are able to polymerize because they all have the same backbone molecules that are able to form a chain of various lengths via lengths via enzymes. The side chains can vary, which gives rise to the variety in the polymer.

3. How many amino acids are there?

There are 22 amino acids according to Napoleon's Buttons.

4. How does this explain the vast number of different proteins possible?

The fact that the backbone is able to create a chain, and that each side chain of amino acid can be different, the possibilities of combinations is amazing. In any given chain, the combination possibilities are 22", where "n" is the number of amino acids linked in a chain.

5. What is the repeating sequence of silk?

The "repeating sequence of glycine-serine-glycine-alanine-glycine-alanine" is in silk.

6. Describe the overall structure of the silk protein structure. What characteristics does this give the silk?

The silk protein structure is a pleated sheet because of the alternating side groups; which then have cross attractions with the oppositely alternating side chain in the next zigzagged chain.

7. What is responsible for its sheen and ease of dying?

Since 80-85 percent of the silk proteins is made up of repeating sequence that has small side chains, these small, tightly packed groups create a uniform surface that reflect light and give it an attractive sheen. The other 15-20 percent of the proteins is made up of amino acids that have side chains which are not part of the "regular pleated sheet structure" and "easily chemically bond with dye molecules"

8. What role does hydrogen bonding play in the silk fiber?

Hydrogen bonding occurs between the hydrogen on the nitrogen and the double bonded oxygen in the backbone, which hold the alternating (side-by-side) amino acid chains together.

9. Why is silk considered a polymer?

Silk is considered a polymer because it is made up of many repeating amino acids.

10. What is the difference chemically between the terms "artificial" and "synthetic"?

"For the purposes, synthetic is taken to mean that a compound is man-made by chemical reactions. The product may be one that occurs in nature or it may not occur naturally...An artificial compound has a different chemical structure from that of another compound, but it has properties similar enough to mimic the other's role".

11. Explain why both silk and nylon are considered condensation polymers rather than addition polymers. (The info and description is in NB but not the use of the chemical terms!)

They are considered condensation polymers and not additional polymers because when the nitrogen bond to the carboxylic acid carbon a water molecule is produced (from a hydrogen bonded to -NH2 and the -OH of the acid).

Napoleon's Buttons- Chapter 2 - Ascorbic Acid

1. What