Chapter 4Cytoskeleton, Cell wall and EMC

You Must Know • The structure and function of the cytoskeleton.

(You will only be tested on the parts of the cytoskeleton that we go over in class today.)

• The structure and function of the plant cell wall and the animal ECM.

• Organelles found only in plant cells or only in animal cells. (Page 72-73)

Concept 4.6: The cytoskeleton is a network of fibers that organizes structures and activities in the cell

• The cytoskeleton is a network of fibers extending throughout the cytoplasm.

• It organizes the cell’s structures and activities, anchoring many organelles.

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Figure 4.21

Receptor formotor protein

Vesicle

Motor protein(ATP powered)

ATP

Microtubuleof cytoskeleton

(a) Motor proteins “walk” vesicles along cytoskeletalfibers.

Roles of the Cytoskeleton: Support and Motility

Microtubule

Centrioles

Centrosome

Centrosomes and Centrioles – animal cells

Cilia and Flagella

Cell Walls of Plants

• The cell wall is an extracellular structure that distinguishes plant cells from animal cells

• Prokaryotes, fungi, and some protists also have cell walls

• The cell wall protects the plant cell, maintains its shape, and prevents excessive uptake of water

• Plant cell walls are made of cellulose fibers embedded in other polysaccharides and protein

© 2014 Pearson Education, Inc.

Figure 4.25

Secondarycell wall

Central vacuole

Primarycell wall

1 m

Middlelamella

Plasmodesmata

Cytosol

Plasma membrane

Plant cell walls

The Extracellular Matrix (ECM) of Animal Cells

The ECM is made up of glycoproteins

Figure 4.27

1 m

Intermediatefilaments

TEM

0.5 mTEM

0.1 mT

EM

Tightjunction

Tightjunction

Ions or smallmolecules

Extracellularmatrix

Gapjunction

Desmosome

Space between cells

Plasma membranesof adjacent cells

Tight junctions preventfluid from movingacross a layer of cells