Protein structure and function Flashcards
(30 cards)
What are the four key levels of protein structure?
Primary (amino acid sequence), Secondary (α-helices and β-sheets), Tertiary (3D folding), Quaternary (multi-subunit assembly).
What determines the primary structure of a protein?
The sequence of amino acids coded by the gene’s mRNA.
What stabilizes the secondary structure of proteins?
Hydrogen bonds between backbone atoms.
What are alpha helices and beta sheets?
Repeating patterns in protein secondary structure; helices are coils, and sheets are folded, pleated structures.
What stabilizes tertiary protein structure?
Side-chain interactions: hydrogen bonds, ionic bonds, disulfide bridges, hydrophobic effects, Van der Waals forces.
What is quaternary structure in proteins?
Arrangement of multiple polypeptide subunits into a functional protein complex.
What is protein folding?
The process by which a polypeptide folds into its functional 3D shape.
What are chaperone proteins?
Proteins that assist other proteins in proper folding.
What can cause protein denaturation?
Heat, pH changes, solvents, or chemicals.
What happens after a protein denatures?
It loses its functional structure and biological activity.
What are the six main protein functions?
Enzymatic, structural, transport, signaling, motor, and immune defense.
What is an example of a structural protein?
Collagen in connective tissue or actin in the cytoskeleton.
Give an example of a transport protein.
Hemoglobin (oxygen transport), or membrane transporters.
Define enzymes.
Proteins that act as biological catalysts to speed up reactions.
What are substrates?
Molecules acted on by enzymes.
What is an enzyme’s active site?
The region where the substrate binds and the reaction occurs.
What is enzyme specificity?
The ability of an enzyme to act only on a specific substrate or reaction.
What is the induced fit model?
The enzyme changes shape slightly to better accommodate the substrate.
What factors influence enzyme activity?
Temperature, pH, substrate concentration, and inhibitors.
What is a competitive inhibitor?
A molecule that competes with the substrate for the active site.
What is a non-competitive inhibitor?
Binds elsewhere on the enzyme, changing its shape and reducing activity.
What are cofactors and coenzymes?
Non-protein helpers; cofactors are inorganic (like metal ions), coenzymes are organic (like vitamins).
What are protein signaling molecules?
Hormones or receptors involved in cell communication.
What are antibodies?
Immune proteins that recognize and bind foreign molecules (antigens).
