Protein Structure and Enzyme Function Quiz

Protein Structure and Function

• Proteins are polymers of amino acids linked by peptide bonds
• Twenty natural amino acids differ by their R-group (side chain)
• Amino acid side chains create a unique chemical surface on a protein, influencing its function
• Hydrophobic amino acids tend to cluster inside a protein; hydrophilic ones are typically on the exterior
• Chemical interactions between side chains stabilize a protein's 3D shape

Enzyme Function

• Enzymes are proteins that catalyze reactions by lowering activation energy (energy needed to start a reaction)
• Enzymes work by binding to a substrate at the active site
• Active site's shape is crucial for specific substrate binding
• Enzymes stabilize the transition state, an intermediate step in a reaction, making the reaction proceed more easily
• Competitive inhibitors resemble the substrate and block binding at the active site
• Non-competitive inhibitors bind to a different site, altering the enzyme's shape and inhibiting its function

Enzyme as Diagnostic Markers

• Enzymes are often confined within cells and not usually present in blood
• Tissue damage or cell breakage releases enzymes into the bloodstream
• Measuring enzyme levels in blood can help diagnose tissue damage/disease
• Examples like ALT (liver enzyme) and PL (pancreatic enzyme)

Enzyme Inhibitors as Drugs

• Some drugs are enzyme inhibitors - they block a specific enzyme's activity
• Competitive inhibitors bind to the active site, preventing substrate binding
• Non-competitive inhibitors bind elsewhere altering the enzyme's shape, blocking the active site's function
• Examples: Penicillin inhibits bacterial enzymes

Cell Membranes

• Cell membranes are primarily composed of a lipid bilayer
• The lipid bilayer features hydrophobic tails (fatty acid chains) and hydrophilic heads
• The hydrophobic tails face inwards, while the hydrophilic heads face outwards interacting with the watery environment.
• The "fluid mosaic model" describes the fluidity of the lipid bilayer, which allows proteins to move within the membrane
• Membrane lipid composition can change in response to environmental temperature changes.

General Cell Properties

• Cells are the basic units of life
• Each cell is enclosed by a lipid membrane
• Cells contain genetic material, generate and utilize energy, and can reproduce