Numerous adult organs possess adult stem cells, which in most cases are multipotent.

TLS Online TPP Program

#Id: 1517

#Unit 2. Cellular Organization

All microtubules are nucleated from structures known as microtubule-organizing centers, or MTOCs.

 

TLS Online TPP Program

#Id: 1518

#Unit 2. Cellular Organization

In MTOCs, 

The (−) end of the microtubule stays anchored in the MTOC while the (+) end extends away from it.

TLS Online TPP Program

#Id: 1519

#Unit 2. Cellular Organization

In cilia and flagella,

microtubules are assembled from an MTOC called a basal body.

TLS Online TPP Program

#Id: 1520

#Unit 2. Cellular Organization

Two different types of microtubule structures can exist, 

one in the T form bound to GTP 

one in the D form bound to GD

TLS Online TPP Program

#Id: 1521

#Unit 2. Cellular Organization

Free-energy change for dissociation of a subunit from the D-form polymer is more favorable (negative) than the free-energy change for dissociation of a subunit from the T-form polymer.

TLS Online TPP Program

#Id: 1522

#Unit 2. Cellular Organization

Hard keratins make up hair and nails. These keratins are rich in cysteine residues that become oxidized to form disulfide bridges, thereby strengthening the proteins.