When Phi is fixed at 0º. Clashes occur at ALL Psi angles. Phi = 0º is physically impossible.

#Id: 396

#Unit 2. Cellular Organization

Each nucleosome added to a covalently closed circular template changes the linking number of the associated DNA by approximately –1.2.

#Id: 397

#Unit 2. Cellular Organization

Nucleosomal DNA wraps around the histone protein 1.65 times, so create a writhe of –1.65 and so DLk should be -1.65. But when the change in linking number associated with each nucleosome was measured, the number was lower than this, approximately –1.2 for each nucleosome added. This discrepancy is referred to as the “Nucleosome Linking Number paradox,”

#Id: 398

#Unit 2. Cellular Organization

#Id: 399

#Unit 2. Cellular Organization

Variants have been identified for all core histones except histone H4.

#Id: 400

#Unit 2. Cellular Organization

MacroH2A is nearly three times larger than conventional H2A, and contains a large C-terminal tail that is not related to any other histone.

#Id: 401

#Unit 2. Cellular Organization