Module 3: Cell Membranes

Module 3: Cell Membranes - Composition of Biological Membranes: - Consist of lipids, proteins, carbohydrates, and nucleic acids. - Lipids and proteins are primary constituents. - Function of Biological Membranes: - Partition water and other water-soluble substances. - Compartmentalize enzymes to enhance chemical reaction efficiency. - Types of Biological Membranes: - Plasma membrane: Outer boundary of life. - Internal membranes (in eukaryotic cells) developed via the endomembrane theory. - Components of Plasma Membrane: - Lipids, proteins, carbohydrate trees, cholesterol, transmembrane proteins (TMP), and peripheral membrane proteins. - TMPs facilitate cell communication via juxtacrine communication. - Fluid Mosaic Model: - Depicts the dynamic nature of biological membranes. - No covalent linkages between different lipids or proteins. - Elasticity and strength derived from lipid properties and protein functions. - Chemical Structure of Lipids: - Comprised of fatty acids, glycerol, and head groups. - Synthesized in the endoplasmic reticulum (ER) as part of the endomembrane system. Module 3 Questions: 1. Explanation of vesicle transport from the Golgi apparatus to the plasma membrane. 2. Evolutionary origin of the endoplasmic reticulum, Golgi apparatus, and vesicles. 3. Concept of orphaned organelles and their evolutionary origin. 4. Origin of mitochondria and its evolutionary significance. 5. Functions of membranes. 6. Difference between triglycerides and phospholipids. 7. Clarification on transmembrane protein characteristics. 8. Accuracy of statements regarding ER and Golgi apparatus. 9. Process of protein entry into the ER. 10. Identification of water solubility and terminology. 11. Vesicle content upon fusion with the plasma membrane. 12. Importance of cholesterol in biological membranes. 13. Comparison of single pass and seven-pass transmembrane proteins. 14. Clarification on active transport mechanism. Module 4: The Cytoskeleton - Composition of Cytoskeleton: - Actin filaments (microfilaments), microtubules, intermediate filaments. - Actin filaments: Cell motility, muscle function, microvilli formation, cell cortex structure. - Microtubules: Cell interior organization, mitotic apparatus, cilia, and flagella. - Intermediate filaments: Nuclear support, cell junctions in epithelia. - Characteristics of Cytoskeletal Components: - Actin filaments and microtubules can assemble and disassemble. - Intermediate filaments provide mechanical strength and flexibility. - Molecular Motors: - Facilitate intracellular transport. - Powered by ATP, travel along actin filaments or microtubules. - Essential for endomembrane system function and membrane flow. - The Nucleus: - Absent in prokaryotes. - Site of ribosomal RNA synthesis, essential for protein synthesis. - Nucleosomal core composed of histones and nucleosomal DNA. Module 4 Questions: 1. Identification of cytoskeletal filament systems involved in molecular motor movement. 2. Clarification of intermediate filament diameter. 3. Confirmation of ATP usage by molecular motors. 4. Description of nucleosomal core components. 5. Role of histone H1 in nucleosomes. 6. Presence of actin filaments in the nucleus. 7. Explanation of naked DNA creation. 8. Extension of actin filaments outside the cell. 9. Requirements for components to enter the nucleus. 10. Composition of chromosomes. 11. Function of intermediate filament system in nucleus protection. 12. Comparison of actin filaments in cilia and microvilli. 13. Distribution of actin filaments and microtubules within cells. 14. Presence of heterochromatin in interphase nuclei.