animal cell - cytoskeleton Flashcards
What is the function of the cytoskeleton in animal cells?
The cytoskeleton provides support, maintains cell shape, and helps position organelles. It is dynamic, breaking down and reassembling to allow shape changes.
What are the three major components of the cytoskeleton?
Microtubules – Largest, made of tubulin proteins
Microfilaments – Smallest, made of actin proteins
Intermediate
Filaments – Medium-sized, made of keratin proteins
What are the functions of microtubules?
Resist compression, help maintain cell shape
Form structures like cilia (rowing motion) and flagella (swimming motion)
Help move organelles within the cell using ATP-powered motor proteins
What are microfilaments made of, and what do they do?
Made of actin subunits, forming linear strands or 3D networks. They:
-Help with cell movement
-Enable muscle contraction via actin-myosin interaction
What makes intermediate filaments unique?
They are supercoiled cables made of keratin, lamins, or neurofilaments.
-Provide tensile strength
-More permanent than microtubules or microfilaments
-Help maintain cell shape even after the cell dies
What are the three major types of cell junctions?
Tight Junctions – Seal neighboring cells tightly to prevent fluid movement
Desmosomes – Anchoring junctions that hold cells together, especially in muscle tissue
Gap Junctions – Allow communication between cells via ion and molecule exchange
What do tight junctions do?
They form a seal between neighboring cells, preventing uncontrolled movement of fluids across cell layers
What is the function of desmosomes?
They act as anchoring junctions, connecting adjacent cells and linking to intermediate filaments for structural support.
How do gap junctions help in cell communication?
They create channels that allow ions and small molecules to pass directly between neighboring cells, enabling rapid intercellular communication.
What is the extracellular matrix (ECM)?
A network of glycoproteins secreted by cells that helps anchor cells and determine tissue function.
What is the ECM made of?
-Collagen fibers embedded in a proteoglycan matrix
-Proteoglycans (proteins with sugar chains) that trap water
-Fibronectins that attach cells to the ECM
-Integrins that connect the ECM to the cytoskeleton
How does the ECM vary in different tissues?
Bone – Hard, mineralized ECM
Cartilage – Softer, collagen-rich ECM
Connective Tissue – Contains elastin and collagen, loosely packed
What are Glycoproteins?
Glycoproteins are proteins with carbohydrate (sugar) chains attached.
Found in cell membranes and body fluids.
lysosome
digestive organelle that hydrolyses macromolecules
plasmodesmata
channels through cell walls which connect the cytoplasm of adjacent cells
