Seedlings grown in the dark display an etiolated growth pattern:

a) yellow unexpanded cotyledons

b) apical hook

c) Long hypocotyl

TLS Online TPP Program

#Id: 484

#Unit 2. Cellular Organization

Heterochromatic regions, silenced genes, and gene-sparse regions of chromosomes are typically localized to the nuclear periphery.

TLS Online TPP Program

#Id: 485

#Unit 2. Cellular Organization

Active genes/euchromatin are often found at the borders of chromosome territories, and active genes from several chromosomes may cluster in inter-chromosomal territories that are enriched in transcription machinery.

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.