PROTEINS

• TRUE OR FALSE

  True - all proteins contain the element carbon, hydrogen, oxygen, and nitrogen; most also contains of sulfur
• Hemoglobin - oxygen-transporting protein of blood
• protein - is a naturally occurring, unbranched polymer in which the monomer units are amino acids
• amino acid - is an organic compound that contains both an amino group (-NH2) and a carboxyl group (-COOH)
• alpha amino acid - is an amino acid in which the amino group and the carboxyl group are attached to the alpha carbon atom
• standard amino acid - is one of the 20 alpha-amino acids normally found in proteins
• nonpolar amino acid - is an amino acid that contains one amino group, one carboxyl group, and a nonpolar side chain
• Glycine - Gly
• Alanine - Ala
• Valine - Val
• Leucine - Leu
• Isoleucine - Ile
• Proline - Pro
• Phenylalanine - Phe
• Methionine - Met
• Tryptophan - Trp
• Serine - Ser
• Cysteine - Cys
• Threonine - Thr
• Asparagine - Asn
• Glutamine - Gln
• Tyrosine - Tyr
• Aspartic Acid - Asp
• Glutamic Acid - Glu
• Histidine - His
• Lysine - Lys
• Arginine - Arg
• polar neutral amino acid - is an amino acid that contains one amino group, one carboxyl group, and a side chain that is polar but neutral
• polar acidic amino acid - is an amino acid that contains one amino group and two carboxyl groups, the second carboxyl group being part of the side chain
• polar basic amino acid - is an amino acid that contains two amino group and one carboxyl group, the second amino group being part of the side chain
• essential amino acid - is a standard amino acid needed for protein synthesis that must be obtained from dietary sources because the human body cannot synthesize it in adequate amounts from other substances
• complete dietary protein - is a protein that contains all of the essential amino acids in the same relative amounts in which the body needs them
• incomplete dietary protein is a protein that does not contain adequate amounts, relative to the body's needs, of one or more of the essential amino acids
• limiting amino acid - is an essential amino acid that is missing, or present in adequate amounts, in an incomple dietary protein
• Complementary dietary proteins - are two or more incomplete dietary proteins that, when combined, provide an adequate amount of all essential amino acids relative to the body's needs.
• amino acids - are white crystalline solids and are not very soluble in water
• Carboxyl groups - in neutral solutions, they have a tendency to lose protein
• Amino groups - in neutral solution, they have a tendency to accept protons
• zwitterion - a molecule that has a positive charge on one atom and a negative charge on another atom, but which has no net charge
• protonated - in low pH, all acid and amino groups are