bme 486

Q1: Describe primary, secondary, tertiary, and quaternary structures of proteins.
A:

  • Primary: Linear sequence of amino acids.

  • Secondary: Local folding into α-helices or β-sheets.

  • Tertiary: 3D structure from side-chain interactions.

  • Quaternary: Assembly of multiple polypeptides.

Q2: What is the isoelectric point of a protein?
A: The pH at which a protein has no net charge and is least soluble.

Q3: Describe the major functions of the following proteins:

  • Collagen: Structural support in connective tissues.

  • Elastin: Provides elasticity to tissues.

  • Fibronectin: Facilitates cell adhesion.

  • Fibrinogen: Precursor to fibrin in clotting.

  • Albumin: Maintains osmotic pressure and transports substances.

  • Hemoglobin: Transports oxygen in blood.

  • Myoglobin: Stores oxygen in muscles.

  • Immunoglobulin G: Neutralizes pathogens.

  • Lysozyme: Breaks down bacterial cell walls.

  • Trypsin: Digestive enzyme cleaving peptide bonds.

Q4: What does “RGD” refer to? Explain its significance.
A: RGD (Arg-Gly-Asp) is a cell adhesion motif in fibronectin that binds to integrins, facilitating cell attachment.

Q5: List the possible interactions between proteins and biomaterial surfaces.
A: Electrostatic, hydrogen bonding, van der Waals, hydrophobic, and covalent interactions.

Q6: How does the size of a protein influence its ability to bind to a biomaterial?
A: Larger proteins have more contact sites but diffuse slower, influencing binding affinity and rate.

Q7: What factors affect the rate of arrival of protein molecules at a surface?
A: Diffusion, thermal convection, flow, and coupled transport mechanisms.

Q8: Understand adsorption isotherm in dimensionless form (θ vs C).
A: It describes surface coverage (θ) as a function of protein concentration (C).

Q9: Describe the significance of Γm and K in the Langmuir equation.
A:

  • Γm: Maximum adsorption capacity.

  • K: Affinity constant indicating binding strength.

Q10: Compare molecular spreading with orientation change for protein adsorption.
A:

  • Molecular spreading: Unfolding to maximize contact.

  • Orientation change: Repositioning without unfolding.

Q11: Why is pure desorption of a protein unlikely?
A: Strong interactions and conformational changes prevent reversal.

Q12: Explain the difference between protein desorption and exchange.
A:

  • Desorption: Protein leaves surface.

  • Exchange: Replaced by another protein with higher affinity.

Q13: Describe the “Vroman effect.”
A: Initial adsorption of abundant, smaller proteins followed by replacement by larger, higher-affinity proteins.

Q14: Describe the deformation of erythrocytes and why it is required.
A: Enables RBCs to pass through narrow capillaries without blocking blood flow.

Q15: Describe the physiological relevance and sequence of events in forming the “platelet plug.”
A:

  1. Adhesion: Platelets bind to exposed collagen.

  2. Activation: Release ADP and thromboxane A2.

  3. Aggregation: Fibrinogen bridges platelets, forming a plug.

Q16: Describe the difference between intrinsic and extrinsic coagulation pathways.
A:

  • Intrinsic: Initiated by contact with collagen or biomaterial.

  • Extrinsic: Triggered by tissue factor release from damaged cells.

Q17: Describe the function of thrombin, tissue plasminogen activator, and plasmin.
A:

  • Thrombin: Converts fibrinogen to fibrin.

  • tPA: Activates plasminogen to plasmin.

  • Plasmin: Degrades fibrin clots (fibrinolysis).

Q18: Describe how heparin functions as an anticoagulant.
A: Enhances antithrombin III activity to inactivate thrombin and other clotting factors.

Q19: Describe fibrinolysis.
A: Breakdown of fibrin clots by plasmin activated from plasminogen.

Q20: What are the functions of eosinophils and basophils?
A:

  • Eosinophils: Combat parasites and modulate allergic responses.

  • Basophils: Release histamine and mediate allergic responses.

Q21: Explain how monocytes, macrophages, and foreign body giant cells are related yet distinct.
A:

  • Monocytes: Immature cells in blood.

  • Macrophages: Mature form in tissues, perform phagocytosis.

  • Foreign body giant cells: Fused macrophages for large objects.

Q22: Explain how basophils and mast cells are related yet distinct.
A:

  • Basophils: Circulate in blood.

  • Mast cells: Reside in tissues; both release histamine.

Q23: Describe the similarities and differences between macrophages and neutrophil functions.
A: Both perform phagocytosis. Neutrophils: Rapid responders, short-lived. Macrophages: Long-lived, antigen presentation.

Q24: Describe opsonization and phagocytosis for digestible vs. indigestible particles.
A:

  • Opsonization: Marking particles with antibodies for phagocytosis.

  • Digestible: Lysosomes degrade particles.

  • Indigestible: May cause chronic inflammation or fibrosis.

Q25: Describe the four stages of the phagocytic response.
A:

  1. Chemotaxis: Movement toward chemical signals.

  2. Adherence: Binding to target.

  3. Ingestion: Engulfment by pseudopodia.

  4. Digestion: Lysosomal enzymes degrade target.

Q26: Describe lamellipodia and diapedesis.
A:

  • Lamellipodia: Actin-based protrusions for cell migration.

  • Diapedesis: Leukocyte movement through vessel walls.

Q27: Describe the potential outcome of smooth or rough biomaterial surfaces.
A:

  • Smooth: Less protein adsorption and thrombosis.

  • Rough: Enhanced protein adsorption and cell adhesion.