#vesicle

Basics of Cell Biology

Which cellular process involves the intake of large molecules via vesicles?

Cells internalize macromolecules too large or polar to cross bilayer via endocytosis involving membrane invagination and vesicle formation consuming energy. Clathrin-mediated endocytosis concentrates receptors such as transferrin receptor, LDL receptor, and EGFR into clathrin-coated pits assembled by adaptor AP2 and accessory proteins EPS15, dynamin GTPase mediates scission producing 100 nm vesicles that shed clathrin via auxilin and Hsc70 and fuse with early endosomes marked by Rab5 and PI3P. Caveolin-dependent uptake forms 60 nm flask-shaped caveolae enriched in cholesterol, regulating lipid

Ref: Alberts et al., Molecular Biology of the Cell, 7th ed., Chapter 13: Endocytosis Mechanisms.

View Details

Properties of Plasma Membrane

What is the key difference between bilayers and liposomes?

Distinction between bilayer organization and vesicular structures illustrates supramolecular assembly hierarchy. Phospholipid bilayer fundamental two-dimensional fluid with two opposed leaflets hydrophobic tails interior hydrocarbon slab three to four nanometer low dielectric excluding water, hydrophilic headgroups hydrated outward facing aqueous phases intra and extracellular, forms flexible sheet capable of undulations bending modulus about ten to twenty kBT, can exist as planar black lipid membrane across aperture separating two aqueous compartments or supported bilayer on mica for AFM. Lip

Ref: Bangham et al., Liposomes as Models of Biological Membranes, J Mol Biol 1965.

View Details

Membrane Transportation

Which of the following is an example of vesicular transport?

Vesicular transport refers to bulk modality moving macromolecules particles and fluid that cannot cross via single carriers by formation of membrane vesicles requiring cytoskeletal remodeling. Endocytosis exemplifies inward trafficking where plasma membrane invaginates forming coated pits concentrated by adaptor AP2 epsin sorting cargo low-density lipoprotein receptor nutrients antigens pathogens. Clathrin triskelion lattice polymerizes imposing curvature dynamin large GTPase forms helical collar around neck hydrolyzing GTP to pinch vesicle releasing one hundred nanometer vesicle containing sa

Ref: Alberts et al., Molecular Biology of the Cell, 6th ed., Chapter 13: Vesicular Transport – Endocytosis as Example.

View Details

Mitochondria Plastids Ribosomes and Other Organelles

Four structures are described below: P: a single-membrane vesicle containing hydrolytic enzymes Q: a membrane-bound spac

Lysosomes contain hydrolytic enzymes, while vacuoles contain water, sap, excretory products and other materials. Mitochondria possess inner-membrane cristae, whereas chloroplasts contain thylakoids arranged into grana.

Ref: NCERT Class 11 Biology Chapter 8: Cell: The Unit of Life Mitochondria Plastids Ribosomes and Other Organelles

View Details