Permits movement of substances within the cell and

permits movement of substances within the cell and movement of external projections
(cilia or microvilli; flagella in sperm) outside the plasma membrane
e. Filaments: collectively promote cell strength, shape, and movement
i. actin filaments: (microfilaments): smaller fibrils that generally occur in bundles
 “wave of excitation” that may cause the spontaneous migration of cells.
 a major driver for many cell functions including cell movement,
endocytosis, and maintenance of cell and tissue shape
 link the interior of the cell to adjacent cells through cell junctions.
 necessary for regulating cell growth and drive the pinching of one cell
into two
 Cellular locomotion depends on contractile properties that involve both
microtubules and actin filaments
ii. microtubules: small, hollow, cylindrical, unbranched tubules made of protein
 exhibit rigidity to add strength to the cell's structure
 support and move organelles from one part of the cytoplasm to another
 facilitate transport of impulses along nerve cells
 roles in the inflammatory and immune responses and hormone
secretion
 involved in the external movement, or motility, of some cells.
 cilia and (eukaryotic) flagella move as a result of microtubules sliding
along each other

 Microtubules involved in cellular division are arranged in a centriole.
During division, the pairs of centrioles split and migrate to opposite
poles of the cell.
iii. intermediate filaments : braided, ropelike fibers made of several filament
proteins.
 The different filaments form a mesh called the nuclear lamina beneath
the inner nuclear membrane, creating a protective chamber for the
cell's DNA
 Others crisscross the cytoplasm, promoting mechanical strength.
 In epithelial tissue these filaments bridge the cytoplasm from one cell
junction to another, supporting and strengthening the sheet of
epithelium
f. Mechanotransduction: the cellular processes that translate mechanical stimuli into
biochemical signals, allowing cells to adapt to their surroundings.
i. These cell adaptations are associated with several alterations and diseases
including loss of hearing, CV disease, muscular dystrophy, and cancer
VI. Caveolae Tiny indentations (caves)
a. Functions: capture extracellular material and shuttle it inside the cell or across the cell.
VII. Vaults Cytoplasmic ribonucleoproteins
a. Functions: act as “trucks,” shuttling molecules from nucleus to elsewhere in cell.
Plasma Membrane
: surround the cell or enclose an intracellular organelles
I. Functions
a. control the composition of the cell by allowing or exclude various molecules , which
greatly influences the metabolic pathways
b. contain selective transport systems that allow them to move molecules in or out of the
space, which greatly influence the metabolic pathways
c. Cell polarity, the direction of cellular transport, maintains normal cell and tissue
structure for numerous functions, most importantly transport of nutrients in and out of
the cell, and becomes altered with diseases such as cancer
d. Cell to-cell recognition
e.