the animal cell Flashcards
complexity structure function and tissue and transport
What are the three major classes of cytoskeletal elements in animal cells?
Microtubules
Intermediate filaments
Microfilaments
What are the functions of the cytoskeleton?
Organizing organelles
Maintaining cell shape
Providing anchorage
Facilitating cell movement
Enabling cell division
Allowing contact and signal transmission
What proteins are associated with the cytoskeleton?
Tubulin, Actin, Keratin, Myosin, Kinesin, Dynein
What distinguishes anchorage-dependent cells?
These cells require attachment to a surface or extracellular matrix (ECM) to maintain their phenotype, direction, and functionality. Examples include skin, bone, liver, and gut cells.
What happens when anchorage-dependent cells lose attachment?
They lose their sense of directionality and cease to function properly.
What is the “tensegrity hypothesis” related to the cytoskeleton?
It suggests that the cytoskeleton operates as a system of compression-resistant struts and tensile cables, maintaining cell shape and mechanical stability.
What are the four ways animal cells attach to each other?
Adherens junctions
Desmosomes
Tight junctions
Gap junctions
What are the properties of adherens junctions?
Act as bands of welds between cells
Anchored to actin filaments of the cytoskeleton
Distribute mechanical stress, including during contraction
Allow intercellular passage of substances
What are desmosomes, and where are they found?
Desmosomes act like rivets or spot welds, providing strong adhesion. Found in strong epithelial tissues like gut and skin.
What are tight junctions, and where are they located?
Tight junctions create impermeable seals between cells. They are found in intestinal epithelial cells and endothelial cells of the blood-brain barrier.
What are gap junctions, and what is their function?
Gap junctions link cytoplasm of adjacent cells, allowing small molecules to pass. They maintain coordinated responses, e.g., in nerve and heart cells.
What are the effects of isotonic, hypertonic, and hypotonic solutions on cells?
Isotonic: No net water movement
Hypertonic: Water moves out, causing cell shrinkage
Hypotonic: Water moves in, causing cell swelling
What are the five mechanisms of membrane transport?Back:
Osmosis
Simple diffusion
Facilitated diffusion
Active transport
Vesicular transport
What is facilitated diffusion?
Solutes move across membranes down a concentration gradient with the help of transporter proteins. Requires no energy.
What is active transport, and give an example?
Active transport moves solutes up a concentration gradient using ATP. Example: Na+/K+ pump.
