chapter 20

Question 1

protein

Answer 1

• Naturally-occurring, unbranched polymer in which the monomer units are amino acids
• Most abundant substance in cells after water
  - Account for about 15% of a cell’s overall mass
• Elemental composition - Carbon (C), hydrogen (H), nitrogen (N), oxygen (O), and sulfur (S)
  
  • Average nitrogen content is 15.4% by mass
• Contain iron (Fe), phosphorus (P), and other metals in certain specialized proteins

Question 2

amino acid

Answer 2

Contain both an amino (—NH2) and a carboxyl (—COOH) group

-700 amino acids known

Question 3

nonpolar amino acids

Answer 3

• Contain one amino group, one carboxyl group, and a nonpolar side chain
  - Hydrophobic - Not attracted to water molecules
  - Found in the interior of proteins, where there is no polarity

Question 4

polar amino acids

Answer 4

• Hydrophilic- water loving

- Types - Polar neutral, polar acidic, and polar basic

Question 5

polar acidic

Answer 5

contain a carboxyl group as part of the side chain

 - 2 amino acids belong to this category 
 - C=O

Question 6

polar basic

Answer 6

contain an amino group as part of the side chain

- 3 amino acids belong to this category 
- NH2