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| Answers |
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| Q: The primary structure of a protein is its _______. |
A: Sequence of amino acids. |
| Q: The secondary structure of a protein is its _______. |
A: Interactions between adjacent amino acids. |
| Q: What are the two types of secondary structures? |
A: Alpha-helix and beta-pleated sheets. |
| Q: What is the tertiary structure of a protein? |
A: Its 3D shape... How the protein folds upon itself. |
| Q: What is the quaternary structure of a protein? |
A: How a series of proteins fit together. |
| Q: Give an example of a quaternary structure. |
A: Hemoglobin. |
| Q: What type of bonds are involved in primary structures? |
A: Peptide bonds. |
| Q: What type of bonds are involved in secondary structures? |
A: Hydrogen bonds (between amine and carbonyl groups within the peptide backbone. |
| Q: What type of bonds are involved in tertiary structures? |
A: They could be covalent, ionic, hydrogen (between amino acid side chains), or hydrophobic. |
| Q: What type of bonds are involved in quaternary structures? |
A: They could be covalent, ionic, hydrogen (between amino acid side chains), or hydrophobic. |
| Q: What are the structural classification of proteins? |
A: Fibrous, globular, and transmembrane. |
| Q: Give two examples of a fibrous protein. |
A: Keratin and collagen. |
| Q: True or false? Fibrous proteins are insoluble. |
A: True! |
| Q: Give two examples of a globular protein. |
A: Myoglobin and hemoglobin. |
| Q: Where would you find transmembrane proteins? |
A: Embedded in the lipid bilayer of plasma membranes extending from one side of the membrane to the other side. |
| Q: Changes in the _______ of proteins will alter function. |
A: Shape. |
| Q: Cystic fibrosis involves a defective _______. |
A: Cl- channel. |
| Q: Familial hypercholesterolemia involves a defective _______. |
A: LDL receptor. |
| Q: What two amino acids would you NOT see in an alpha-helix? |
A: Proline and glycine. |
| Q: An alpha-helix makes a complete turn every _______ amino acids. |
A: 3.6 |
| Q: In an alpha-helix the R-groups of the amino acids face to the _______. |
A: Outside. |
| Q: Is an alpha-helix a right or left handed helical shape? |
A: Right-handed. (I saw an old test question that mentioned D-amino acids... remember, we are talking only about L-amino acids here) |
| Q: What does a beta-sheet consist of? |
A: They consist of pairs of chains lying side by side. |
| Q: What stabilizes a beta-pleated sheet? |
A: Hydrogen bonds between the carbonyl oxygen atom on one chain and the -NH group on the adjacent chain. |
| Q: How are beta-pleated sheet arranged? |
A: In an anti-parallel fashion. |
| Q: What is the most common non-repetitive secondary structure? |
A: The beta-turn which is a reverse turn or hairpin bend. Proline and glycine are common here. |
| Q: A protein is said to be _______ when it loses its activity. |
A: Denatured. |
| Q: Are intracellular and extracellular domains hydrophilic or hydrophobic? |
A: Hyrophilic. |
| Q: True or false? The tertiary structure of transmembrane proteins often has two hydrophilic domains and one hydrophobic domain. |
A: True! |
| Q: The hydrophobic membrane spanning domain are typically what specific structure? |
A: An alpha-helix. |
| Q: What is a quaternary structure? |
A: Complexes of two or more polypeptide chains held together in precise ratios and with a precise 3D configuration. |
| Q: Where would you find myoglobin? |
A: In muscle tissue. |
| Q: What is the function of myoglobin? |
A: Oxygen storage. |
| Q: Myoglobin can bind to how many oxygen molecules? |
A: One. |
| Q: What is the structure of myoglobin? |
A: A globin chain and a single heme ring. |
| Q: Where would you find hemoglobin? |
A: In RBCs. |
| Q: What is the function of hemoglobin? |
A: Oxygen transportation. |
| Q: Hemoglobin can bind to how many oxygen molecules? |
A: Four. |
| Q: What is the structure of hemoglobin? |
A: Four globin chains (2 alpha & 2 beta) and four heme rings. |
| Q: What is the abbreviation for hemoglobin? |
A: Hb. |
| Q: Myoglobin is considered a _______ protein. |
A: Monomeric. |
| Q: Hemoglobin is considered a _______ protein. |
A: Tetrameric. |
| Q: In deoxyhemoglobin each heme residue contains the ferrous form of iron (Fe2+). What stabilizes the iron? |
A: Histidine. |
| Q: In O2 hemoglobin what stabilizes the oxygen? |
A: A distal histidine. |
