Chapter 17: Control of Gene
Expression in Eukaryotes
17.1 Eukaryotic Cells and Bacteria Have Many Features of
Gene Regulation in Common, but They Diff er in Several
Important Ways
Each structural gene has its own promoter and is transcribed
separately.
DNA must unwind from the histone proteins before transcription.
Transcription and translation are separated in time and space.
Figure 1 Chromatin has a highly complex structure with
several levels of organization.
Chromosome puffs are regions of
relaxed chromatin where active
transcription is taking place
DNAse I digests DNA that are NOT
tightly bound to histones
What is the nature of the change in
chromosome puffs and DNA
sensitivity?
, 17.2 Changes in Chromatin Structure Aff ect the Expression
of Genes
- DNase I
hypersensitivity
o DNase I
hypersensitive
sites: more
open chromatin
configuration
site, upstream
of the
transcription
start site
- Histone
modification
o Addition of
methyl groups
(CH3) to the
histone protein
tails (lysine or
arginine)
o Addition of Figure 2 The acetylation of histone proteins alters chromatin structure and permits some
acetyl groups transcription factors to bind to DNA.
(CH3CO) to histone proteins (Lysine)
- Acetylation of histones controls flowering in Arabidopsis
o Flowering locus C (FLC) gene
o Flowering locus
D (FLD) gene
- Chromatin
remodeling
o Chromatin-
remodeling
complexes: bind
directly to DNA
sites and
reposition
nucleosomes
- DNA methylation
Expression in Eukaryotes
17.1 Eukaryotic Cells and Bacteria Have Many Features of
Gene Regulation in Common, but They Diff er in Several
Important Ways
Each structural gene has its own promoter and is transcribed
separately.
DNA must unwind from the histone proteins before transcription.
Transcription and translation are separated in time and space.
Figure 1 Chromatin has a highly complex structure with
several levels of organization.
Chromosome puffs are regions of
relaxed chromatin where active
transcription is taking place
DNAse I digests DNA that are NOT
tightly bound to histones
What is the nature of the change in
chromosome puffs and DNA
sensitivity?
, 17.2 Changes in Chromatin Structure Aff ect the Expression
of Genes
- DNase I
hypersensitivity
o DNase I
hypersensitive
sites: more
open chromatin
configuration
site, upstream
of the
transcription
start site
- Histone
modification
o Addition of
methyl groups
(CH3) to the
histone protein
tails (lysine or
arginine)
o Addition of Figure 2 The acetylation of histone proteins alters chromatin structure and permits some
acetyl groups transcription factors to bind to DNA.
(CH3CO) to histone proteins (Lysine)
- Acetylation of histones controls flowering in Arabidopsis
o Flowering locus C (FLC) gene
o Flowering locus
D (FLD) gene
- Chromatin
remodeling
o Chromatin-
remodeling
complexes: bind
directly to DNA
sites and
reposition
nucleosomes
- DNA methylation
