Podcast
Questions and Answers
What is the primary requirement for Ca2+-dependent exocytosis to occur?
What is the primary requirement for Ca2+-dependent exocytosis to occur?
Which process is NOT a step in exocytosis?
Which process is NOT a step in exocytosis?
What role do motor proteins play in vesicle trafficking?
What role do motor proteins play in vesicle trafficking?
What is the primary function of vesicle tethering in exocytosis?
What is the primary function of vesicle tethering in exocytosis?
Signup and view all the answers
During which step of exocytosis do vesicles release their contents outside the cell?
During which step of exocytosis do vesicles release their contents outside the cell?
Signup and view all the answers
What distinguishes macrotransfer from microtransfer processes?
What distinguishes macrotransfer from microtransfer processes?
Signup and view all the answers
Which process involves the movement of substances out of the cell?
Which process involves the movement of substances out of the cell?
Signup and view all the answers
What happens during exocytosis?
What happens during exocytosis?
Signup and view all the answers
Which of the following is a type of exocytosis?
Which of the following is a type of exocytosis?
Signup and view all the answers
Which of the following characterizes receptor-mediated endocytosis?
Which of the following characterizes receptor-mediated endocytosis?
Signup and view all the answers
What is the primary function of constitutive secretion?
What is the primary function of constitutive secretion?
Signup and view all the answers
Which of the following best describes phagocytosis?
Which of the following best describes phagocytosis?
Signup and view all the answers
Fluid-phase pinocytosis is characterized by which of the following?
Fluid-phase pinocytosis is characterized by which of the following?
Signup and view all the answers
Study Notes
Biological Membranes: Transport I (Macrotransfer)
- Class: Foundation Year
- Course: Fundamentals of Human Biology
- Code: FUNBIO.9
- Lecturer: Dr Irene Oglesby
- Date: 16th October 2024
Learning Outcomes
- ALO1: Recall the difference between macrotransfer and microtransfer processes.
- ALO2: Differentiate between exocytosis and endocytosis.
- ALO3: Explain the mechanism of phagocytosis and pinocytosis.
- ALO4: Differentiate between receptor-mediated and fluid-phase pinocytosis.
- ALO5: Describe 4 stages in the secretory vesicle formation.
- ALO6: Differentiate between constitutive and regulated secretion.
Membrane Transport
-
Macrotransfer: Transport of large molecules and larger items into and out of the cell.
- Exocytosis: Movement out of the cell.
- Endocytosis: Movement into the cell.
-
Microtransfer: Passive and Active transportation.
- Passive: Movement across the membrane without energy input.
- Active: Movement across the membrane requiring energy input.
Exocytosis
- Process: Releasing large biomolecules through the plasma membrane.
-
Tasks:
- Increases the surface area of the plasma membrane.
- Releases substances within vesicles into the exterior.
- Incorporates vesicle membrane proteins into the plasma membrane.
Types of Exocytosis
- Constitutive: Non-Ca2+ dependent. Continuously occurs.
- Ca2+ dependent: Regulated exocytosis stimulated by signaling molecules.
Ca2+-mediated Exocytosis
- Requires presence of Calcium for vesicle release.
-
Important Processes:
- Neuronal communication - converting electrical to chemical signals (at the synapse)
- Hormone release - e.g., insulin from beta cells.
Distinct Steps in Exocytosis
- 1. Vesicle Trafficking: Movement of vesicles from production site to release site.
- 2. Tethering: Formation of a bridging complex facilitated by proteins like Rab.
- 3. Docking: Attachment of vesicle membrane to target cell membrane.
- 4. Priming: Molecular rearrangements and ATP-dependent modifications.
- 5. Fusion: Phospholipid bilayers merge, driven by SNARE proteins, releasing large biomolecules.
Endocytosis
- Process: Cells absorb molecules like proteins from the exterior.
- Purpose: Uptakes polar & large molecules that can't pass through the hydrophobic plasma membrane.
Subcategories of Endocytosis
- Phagocytosis: Engulfing large particles (e.g., bacteria).
- Pinocytosis: Engulfing materials dissolved in the surrounding medium.
Pinocytosis
- Types:
- Receptor-mediated: Molecules bind to receptors on the plasma membrane, then adsorbed.
- Fluid-phase: No receptors are involved.
Phagocytosis
-
Process:
- Plasma membrane extends to engulf material.
- Receptors can bind to antibodies on foreign bodies.
- Formation of an intracellular vacuole(phagosome)
- Fusion with lysosomes(formation of a secondary lysosome).
- Digestion of engulfed material.
Macrophage Activity
- Macrophages can engulf 25% of their volume each hour via pinocytosis.
- This process removes 3% of their plasma membrane per minute.
- Exocytosis must balance endocytosis to maintain cell structure and function.
Reading Material
- Chapters 5 (Solomon 11th edition): Online resources for additional study on diffusion, sodium-potassium pump, membrane transport, and synaptic vesicle trafficking.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Related Documents
Description
This quiz covers the key concepts of macrotransfer in biological membranes, focusing on processes such as exocytosis and endocytosis. You will differentiate between various transport mechanisms and explain the stages involved in secretory vesicle formation. Master the understanding of cell transport in the context of human biology.
