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Chapter 5:
Biomembranes and Cell
Architecture
By: Anna Whiteshield
Overview
Lipid Composition
 Protein Components
 Organelles of Eukaryotic Cell
 Cytoskeleton
 Purification of Cells
 Visualizing Cell Architecture

Overview of the cytoskeleton
Three types of filaments in the
cytosol

Actin also known as Microfilaments

Microtubules

Intermediate filaments
Organization of the filaments

Bundles
 Filaments

are closely packed in parallel arrays.
Networks
 Filaments
packed.
crisscross at right angles and loosely
Microfilaments

Structural support and motility
 Actin

Composed of polymerized α- and β-tubulin

Membrane-microfilament binding proteins
connect them to the membrane
Intermediate Filaments

Support for Nuclear membrane
 Lamins

Cell adhesion
 Desmin,

Motility
 MSP
keratin, vimentin.
Microtubules

Structural support, motility, cell polarity
α
and β Tubulin

Cell division (bacteria)

Necessary for endoplasmic reticulum
location and formation of mitotic apparatus
Summary
Cytoskeleton provides structural stability
and movement for the cell.
 Microfilaments and their proteins form a
skeleton underneath the plasma
membrane
 Intermediate filaments mediate cell-cell
adhesion and cell-matrix adhesion.
 Microtubules radiate from centrosome
forming the MTOC.

References:

http://bio.winona.edu/bates/Bio241/cells.htm

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.