Extracellular Components Extracellular Matrix of Animal Cells Functions

Extracellular Components

Extracellular Matrix of Animal Cells § Functions in support, movement, and regulation § Synthesized and secreted by cells § Composed of strong fibers of collagen § Holds cells together and protects the plasma membrane § Attaches through connecting proteins that bind to membrane proteins called integrins § Integrins span the plasma membrane and connect to microfilaments of the cytoskeleton

Extracellular Matrix of Animal Cells

Extracellular Matrix of Animal Cells

Functions of the ECM – – Support Adhesion Movement Regulation Copyright © 2008 Pearson Education, Inc. , publishing as Pearson Benjamin Cummings

Cell Junctions in Animal Tissues § Adjacent cells communicate, interact, and adhere through specialized junctions between them – Tight junctions – Anchoring junctions – Gap junctions – Plasmodesmata

Tight Junctions § Prevent leakage of extracellular fluid across a layer of epithelial cells Animation: Tight Junctions

Anchoring Junctions Fasten cells together into sheets Animation: Anchoring Junctions (Desmosomes)

Gap Junctions Channels that allow molecules to flow between cells Animation: Gap Junctions

Cell Walls § Plant, but not animal cells, have a rigid cell wall – It protects and provides skeletal support that helps keep the plant upright against gravity – Plant cell walls are composed primarily of cellulose § Plant cells have cell junctions called plasmodesmata that serve in communication between cells Copyright © 2009 Pearson Education, Inc.

Plasmodesmata • Channels that perforate plant cell walls • Water and small solutes (and sometimes proteins and RNA) can pass from cell to cell Copyright © 2008 Pearson Education, Inc. , publishing as Pearson Benjamin Cummings

The Cell A Living Unit Greater Than the Sum of Its Parts • Cells rely on the integration of structures and organelles in order to function • A macrophage’s ability to destroy bacteria involves the whole cell, coordinating components such as the cytoskeleton, lysosomes, and plasma membrane Copyright © 2008 Pearson Education, Inc. , publishing as Pearson Benjamin Cummings

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