Density-independent factors limit population size regardless of the population’s density.

Common density-independent factors include natural disasters such as tornadoes, hurricanes, floods, and fires.

TLS Online TPP Program

#Id: 1392

#Unit 4. Cell Communication and Cell Signaling

The giant protein titin extends through the thick filaments and attaches to the Z disk.

TLS Online TPP Program

#Id: 1393

#Unit 4. Cell Communication and Cell Signaling

Nebulin binds actin subunits and determines the length of the thin filament.

TLS Online TPP Program

#Id: 1394

#Unit 4. Cell Communication and Cell Signaling

CapZ blocks the (+) end, which is where filaments normally grow, so its function is to limit actin dynamics to the (−) end.

TLS Online TPP Program

#Id: 1395

#Unit 4. Cell Communication and Cell Signaling

Tropomodulin blocks (−) ends, where filament disassembly normally occurs; thus the major function of tropomodulin is to stabilize filaments .

TLS Online TPP Program

#Id: 1396

#Unit 4. Cell Communication and Cell Signaling

All small GTPases of the Ras superfamily, Cdc42, Rac, and Rho act as molecular switches, inactive in the GDP-bound state and active in the GTP-bound state.

TLS Online TPP Program

#Id: 1397

#Unit 4. Cell Communication and Cell Signaling

Actin-based motors powered by ATP hydrolysis.