bio chapter 11 cell-cell interactions

PWhat is the primary function of the plasma membrane?
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A: Create an internal environment different from the outside; selective permeability.

Q: What is the extracellular matrix (ECM) in animals made of?

A: Collagen (fibrous) + proteoglycans (gel ground substance).

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Flashcard 3
Q: What is the primary plant cell wall made of?

A: Cellulose microfibrils + pectin polysaccharides (moisture & flexibility).

Q: What is the function of expansins in plants?

A: Break cross-links in cell walls to allow growth.

Q: What are tight junctions?

A: Membrane proteins that create watertight seals between cells (common in epithelia).

Q: What are desmosomes and what proteins are key in them?

A: Strong adhesion linking cytoskeletons. Key proteins: cadherins.

Q: What are gap junctions in animals vs plasmodesmata in plants?

A: Gap junctions: protein channels for small molecules/ions.
Plasmodesmata: cytoplasmic connections through cell walls.

Q: What are hormones and how do they signal?

A: Signaling molecules secreted into body, act on target cells with receptors.

Q: Difference between lipid-soluble vs lipid-insoluble signals?

A: Lipid-soluble: diffuse, bind inside cell, alter gene expression.
Lipid-insoluble: bind surface receptors → signal transduction cascade.

Flashcard 10
Q: What is quorum sensing?

A: Cell-cell signaling in unicellular organisms in response to population density.