How do the extracellular filaments in plants differ from those in animals?
a. Plant filaments resist compression forces; animal filaments resist pulling forces.
b. Animal filaments consist of proteins; plant filaments consist of polysaccharides.
c. Plant extracellular filaments never move; animal filaments can slide past one another.
d. Plant filaments run parallel to one another; animal filaments crisscross.

Which of the following actions correctly describe a role performed by at least one type of intercellular connection? Select True or False for each statement.

T/FAllows communication between adjacent cells.

T/FForms a watertight barrier between the cells.

T/FUses components of the extracellular matrix to indirectly connect adjacent cells.

T/FAssociates with cytoskeletal components to resist pulling forces.

Summarize the experimental evidence in sponges showing that animal cells adhere to each other selectively. Explain the molecular basis of selective adhesion.

Where are protein components of the extracellular matrix synthesized?

a. In the rough ER

b. In the Golgi apparatus

c. In the plasma membrane

d. In the extracellular layer itself

What is the significance of the observation that many signal transduction pathways create a network, where they intersect or overlap?

Suppose you were to model amplification by the phosphorylation cascade in Figure 11.16, using a penny for each kinase 1, a nickel for each kinase 2, and a dime for each kinase 3. Also suppose that Ras and each of the kinases can activate 10 proteins. How much money would you need to construct your model?

What does it mean to say that a signal is transduced?

a. The signaling molecule enters the cell directly and elicits a cellular response.

b. The signal is generated by the production of proteins.

c. The physical form of the signal changes between the outside of the cell and the inside.

d. The signal is amplified.