Runaway selection: Females choose mates without the offering of obvious material benefits or parenting skills, and instead make their choices based on plumage color or courtship peahen may choose her peacock with long tail feather.

TLS Online TPP Program

#Id: 1504

#Unit 2. Cellular Organization

Microtubules are polymers of the protein tubulin.

TLS Online TPP Program

#Id: 1505

#Unit 2. Cellular Organization

The tubulin subunit is a heterodimer formed from two closely related globular proteins called a-tubulin and b-tubulin.

TLS Online TPP Program

#Id: 1506

#Unit 2. Cellular Organization

a-tubulin and b-tubulin comprising 445–450 amino acids, which are tightly held together by noncovalent bonds.

TLS Online TPP Program

#Id: 1507

#Unit 2. Cellular Organization

Each α or β monomer has a binding site for one molecule of GTP.

TLS Online TPP Program

#Id: 1508

#Unit 2. Cellular Organization

The GTP that is bound to α-tubulin is physically trapped at the dimer interface and is never hydrolyzed.

TLS Online TPP Program

#Id: 1509

#Unit 2. Cellular Organization

GTP-binding site on the β-subunit is at the surface of the dimer and GTP bound by the β-subunit can be hydrolyzed.