Eukaryotic Gene Expression PPT Slides
|How are various cell types differentiated?||Differential gene expression|
|Levels at which gene expression is regulated? (6)|| 1. Chromatin remodeling|
3. RNA procession
4. mRNA stability
6. post-translation modification
(folding, transport, activation, degradation of protein)
|What strongly influences chromatin structure?||histone|
|Types of histone modification? (2)|| 1. Histone acetylation (gene activation)|
2. Histone methylation (gene inactivation or activation)
|What does Histone acetylation do?|| Promotes gene expression|
Actetylation of histone proteins affects the level of condensation of DNA
|What do histone proteins form?||They form nucleosomes. (8 histone proteins)|
|What links nucleosomes?||linker DNA|
|Histone proteins help do what to DNA?||condense|
|Nucleosomes may be grouped into what?|| 30-nanometer fibers|
|What does acetylation do?|| Decondenses chromatin|
Promotes loose chromatin structure that permits transcription
|What enzymes results in gene activation?||HAT Enzymes Acetylate DNA, opening it up|
|What enzymes result in gene inactivation?||HDAC Enzymes Deacetylate DNA, condensing it.|
|What does methylation do?|| Regulates gene expression|
May turn it on or off
|What is epigenetic inheritance and how does it relate to methylation?|| epigenetic inheritance is...|
Patterns of methylation (and acetylation) of genes is passed on to daughter cells.
|Transcription in Eukaryotes - OVerview|| RNA polymoerase doesn't bind directly to the promotor|
Basal transcription factors bind first to the promotor (no sigma factor)
promter usually consisters of a TaTA box.
Noncoding introns interspersed within the gene itself
|What are promoter proximal elements?||DNA sequence upstream of promoter, unique to a particular gene|
|What are enhancers?|| Distal elements|
Found much further from promoter
Transcription control elements
|Can a regulatory sequence in DNA be located far from the promoter?||Regulatory sequences in DNA may be located far from the promoter. In an intron, for example.|
|Every eukaryotic gene has multiple....||enhancers. All around the promotor, far and close.|
|How do enahncers control gene expression?||cell-specific regulatory proteins that bind enhancers and activate transcription.|
|What happens when regulatory transcription factors bind to DNA?||Chromatin decondenses via acetylation and other mechanisms.|
|What happens to DNA when chromatin decondenses?||Regions of it are exposed, including the promoter.|
|What do regulatory transcription factors recruit? Where?||Basal transcription complex proteins. To the promoter.|
|What completes the basal transcription complex and begins transcription?||RNA Polymerase II|
|Overview - Transcription control|| 1. Reg transcription factors bind DNA.|
2. Chromatin decondenses via acetylation.
3. Promoter on DNA is exposed.
4. Reg transcription factors recruit basal transcription complex proteins to promoter.
5. RNA polymerase II completes the basal transcription complex.
6. Transcription begins.
|What are some post-transcription controls? (2)|| 1. alternative splicing (exons selectively spliced)|
2. Targeted destruction (mRNAs have variable lifespans)
|What do microRNAs do?||Target selected mRNA molecules for destruction.|
|What do RISC proteins do?|| RNA Interference.|
Form complex with microRNAs.
Recognize and cut mRNA or black translation.