BMB 401 Lecture Notes - Lecture 6: Chromatin Remodeling, Nucleosome, Chromatin
16 Dec 2016
School
Department
Course
Professor
Gene Regulation 4.6
• 2
o A lot of basic stuff in body is not regulated and these housekeeping genes are
constitutively active (like BTFs)
o Gene regulation = when it is on, rate at which to turn it on and duration for
which it is turned on
o Hierarchical! 2 levels are chromatin level and transcriptional level (2 key stages)
• 3
o Many ways to control it before protein is made and can also modify actual
protein if it is made to silence it or degrade it
o Maintains homeostasis and this slide shows main regulation steps and we will
discuss 2 from slide 2
4.6a Chromatin Remodeling
• 5
o Changing chromatin structure (adding/removing)
o DNA exists in form wrapped around histone proteins called nucleosome
▪ These are building blocks for chromatin (higher-order)
o Chromatin is highly condensed DNA and also protects the DNA
o Chromatin remodeling is DNA being exposed and packaged again
▪ Histone modification and DNA methylation
▪ Anything that affects chromatin structure is part of this remodeling
▪ Under control of chromatin-remodeling protein complexes
o Modify histone to expose DNA and modify something else and allow it to
package and this is how we edit it
• 6
o DNA is super long in our human body so extremely necessary to package it
tightly around histones
• 7
o Heterochromatin = very condenses and inactive form
o Euchromatin = loosely packed and transcriptionally-active chromatin form
• 8
o 5 major classes of histones and they are highly basic and so binds well to –
charged DNA
o Very conserved (H4 the most) and H1 displays highest variability b/w species
• 9
o Almost 10-fold compression thanks to negative supercoiling
▪ Left handed turn = – and vice versa
o Nucleosome made up of histone octamer which DNA wraps around
o H1 not integral component of nucleosome (it serves as glue b/w nucleosomes)
find more resources at oneclass.com
find more resources at oneclass.com
