Cell-Cell Interactions and Signaling in Organisms Chapter 11 (copy)

What is the primary function of the cell membrane?

To create an environment inside the cell that is different from conditions outside.

What are the two types of proteins found in the phospholipid bilayer?

Integral and peripheral proteins.

What is the extracellular matrix (ECM) in animals primarily composed of?

A fiber composite called collagen and proteoglycans.

How does the extracellular matrix (ECM) function in animal cells?

It binds together to form a flexible extracellular layer and helps transmit signals.

What is the role of integrins in the extracellular matrix?

Integrins connect the ECM to the cytoskeleton and help transmit signals.

What is the primary cell wall in plants made of?

Cable-like microfibrils bundled into long strands of cellulose.

How does turgor pressure affect plant cells?

It is important in young, growing plant cells and helps define their shape.

What proteins do mature plant cells secrete to form a secondary cell wall?

Waxes in leaf cells and lignin in cells that form wood.

What is the middle lamella in plant cells?

A gelatinous layer comprised of pectins that glues adjacent plant cells together.

What are tight junctions in animal cells?

Membrane proteins that stitch two cells together with a watertight seal.

What is the function of desmosomes in animal cells?

They link the cytoskeletons of adjacent cells to resist pulling and shearing forces.

What are gap junctions?

Channels that connect adjacent animal cells and allow the flow of small molecules between them.

What are plasmodesmata?

Narrow threads of cytoplasm that pass through the cell walls of adjacent plant cells.

What are hormones in the context of cell signaling?

Information-carrying molecules secreted from a cell that circulate in the body and act on distant target cells.

What distinguishes lipid-soluble hormones from lipid-insoluble hormones?

Lipid-soluble hormones can diffuse across the plasma membrane, while lipid-insoluble hormones cannot.

What happens when a hormone binds to its receptor?

The signal receptor changes shape and activity, allowing the cell to respond.

What is signal transduction?

The process by which a signal binds at the cell surface and triggers an intracellular response.

What are second messengers in cell signaling?

Molecules that are produced inside the cell as a result of G-protein-coupled receptors activating.

What is the role of phosphatases in signal deactivation?

They remove phosphate groups from proteins in the phosphorylation cascade, turning off cell signals.

What is quorum sensing?

A signaling pathway that responds to population density in unicellular organisms.

How do bacteria use quorum sensing?

They release species-specific signaling molecules when their numbers reach a specific threshold.

What is one example of a response to quorum sensing in bacteria?

Bacteria can help glue a community of microbes to a biofilm.

What is a common feature of signaling in unicellular organisms?

It often involves responding to changes in the environment.

What is the significance of signal deactivation in cell signaling?

It allows the cell to remain sensitive to small changes in signaling.

What is the function of expansins in plant cells?

They disrupt cross-linking between microfibrils to allow the cell to grow.

What is the relationship between the extracellular matrix and the cytoskeleton?

The ECM is attached to the cytoskeleton via integrins, which anchor it and help transmit signals.