SA node has Prepotential or pacemaker potential which is the gradual potential rise from the resting membrane potential to threshold  ( -40 mV) & this occur spontaneously.

TLS Online TPP Program

#Id: 486

#Unit 2. Cellular Organization

MARs are AT rich heterochromatic regions which contains cis-acting sites that regulate transcription, 5’ introns, and a recognition site for topoisomerase II is usually present in the MAR.

TLS Online TPP Program

#Id: 487

#Unit 2. Cellular Organization

Presence of topoisomerase II binding sites shows high degree of negative supercoiling is usually present in the MAR.

TLS Online TPP Program

#Id: 488

#Unit 2. Cellular Organization

(MARs) also called scaffold attachment regions (SARs), or S/MARs in case of metaphase chromosome as the same sequences appear to attach to the protein substructure in both metaphase and interphase cells.

TLS Online TPP Program

#Id: 489

#Unit 2. Cellular Organization

In interphase nuclei, this underlying proteinaceous structure changes its organization to occupy the entire nucleus; during interphase the structure is referred to as the matrix rather than the scaffold.

TLS Online TPP Program

#Id: 490

#Unit 2. Cellular Organization

S/MARs is a DNA sequence which binds to base structure called scaffold.

TLS Online TPP Program

#Id: 491

#Unit 2. Cellular Organization

If histones are depleted from a metaphase chromosome and viewed under a transmission electron microscope shows SCAFFOLD.