| Question | Answer |
| Proteins | Polymers of amino acids |
| Amino acids | The basic building blocks of polymers |
| List the biological functions of proteins. | 1. Catalytic Function 2. Transport and Storage 3. Coordinated Motion 4. Structural & Mechanical Support 5. Defense Function 6. Generation & Transmission of Nerve Impulses 7. Control of Growth & Differentiation |
| What does each amino acid have? | An amino group, a carboxyl group, a hydrogen atom, and a side chain bonded to an alpha-carbon atom. |
| Describe the amino acid at physiologic pH. | The carboxyl dissociates, forming the negatively charged ion.
The amino group is protonated, forming the positively charged ion. |
| How many acids make up the proteins in the body? | 20 |
| How do different side chains vary from each other? | Size
Shape
Charge
Hydrogen-bonding capacity
Chemical reactivity |
| What is the simplest amino acid? | Glycine (Gly - G) |
| What are the polar, positively charged amino acids? | Lysine (Lys - K)
Arginine (Arg - R)
Histidine (His - H) |
| What are the polar, negatively charged amino acids? | Aspartic Acid (Asp - D)
Glutamic Acid (Glu - E) |
| Which 2 amino acids have sulfur? | Methionine (Met - M)
Cysteine (Cys - C) |
| What are the amino acids with the aromatic R-groups?
Which are nonpolar, and which are polar? | Nonpolar:
Phenylalanine
Trytophan
Polar:
Tyrosine (because it has a hydroxyl group) |
| Give some examples of hydrophobic amino acids. | Glycine
Methionine
Proline |
| Give an example of a polar, uncharged amino acid. | Cysteine |
| Which amino acid has a nonpolar, aliphatic, cyclic R group? | Proline |
| Which are the most hydrophilic R groups? | The amino acids that are either positively or negatively charged.
+ve:
Lys - His - Arg
-ve:
Asp - Glu |
| What is the difference between essential and nonessential amino acids? | Essential: cannot be synthesized in the body and must be taken in the diet.
Nonessential: can be synthesized in the body; not needed in the diet |
| What is the difference between ketogenic, glucogenic, and mixed amino acids? | Ketogenic: give ketone bodies
Glucogenic: give glucose
Mixed: give both ketone bodies and glucose |
| Which amino acid is both nonessential and ketogenic and glucogenic? | Tyrosine |
| Which amino acids are both essential and ketogenic and glucogenic? | Phenylalanine
Tryptophan
Isoleucine |
| Which amino acids are both essential and ketogenic? | Leucine
Lysine |
| What is the largest amino acid? | Tryptophan |
| Which amino acid does not have a stereoisomer? | Glycine |
| If the amino acid has a stereoisomer, the alpha-carbon is called _____. | asymmetric (chiral) |
| What are the 2 possible forms of stereoisomers?
Which one is found in amino acid residues? | L-form and D-form.
L-form |
| How does an amino acid behave in an acidic medium? Basic medium?
What is this property called? | Acidic medium: proton acceptor
Basic medium: proton donor
This is an amphoteric property. |
| What is the pI? | Isoelectric point: a specific pH where the amino acid is fully ionized but electrically neutral. |
| What is the amino acid called at pI? | Zwitter ion |
