Chapter 5 Biomembranes and Cell Architecture By Anna

Chapter 5: Biomembranes and Cell Architecture By: Anna Whiteshield

Overview Lipid Composition l Protein Components l Organelles of Eukaryotic Cell l Cytoskeleton l Purification of Cells l Visualizing Cell Architecture l

Overview of the cytoskeleton

Three types of filaments in the cytosol l Actin also known as Microfilaments l Microtubules l Intermediate filaments

Organization of the filaments l Bundles l Filaments l are closely packed in parallel arrays. Networks l Filaments packed. crisscross at right angles and loosely

Microfilaments l Structural support and motility l Actin l Composed of polymerized α- and β-tubulin l Membrane-microfilament binding proteins connect them to the membrane

Intermediate Filaments l Support for Nuclear membrane l Lamins l Cell adhesion l Desmin, l Motility l MSP keratin, vimentin.

Microtubules l Structural support, motility, cell polarity lα and β Tubulin l Cell division (bacteria) l Necessary for endoplasmic reticulum location and formation of mitotic apparatus

Summary Cytoskeleton provides structural stability and movement for the cell. l Microfilaments and their proteins form a skeleton underneath the plasma membrane l Intermediate filaments mediate cell-cell adhesion and cell-matrix adhesion. l Microtubules radiate from centrosome forming the MTOC. l

References: l http: //bio. winona. edu/bates/Bio 241/cells. htm l Lodish, H. , A. Berk, P. Matsudaira, C. A. Kaiser, M. Krieger, M. P. Scott, S. L. Zipursky, and J. Darnell. 2004. Biomembranes and Cell Architecture. P. 174 -178. Molecular Cell Biology. W. H. Freeman and Company, New York.