control of gene expression 2 Flashcards
control of eukaryotic transcriptional initiation
- activator proteins bind upstream the enhancer sequence and active the basal transcription complex
- multiple epigenetic mechanisms control gene expression via local chromatin condensation: histone modification and in vertebras’ direct DNA methylation on cytosine helps maintain patterns of gene repression in some somatic cells
multiple epigenetic mechanisms control gene expression via local chromatin condensation:
histone modification and in vertebras’ direct DNA methylation on cytosine helps maintain patterns of gene repression in some somatic cells
around 95% of human genes show..
alternative splicing -introns ar removed from pre-mRNA
![](https://s3.amazonaws.com/brainscape-prod/system/cm/203/759/112/a_image_thumb.png?1482591440)
RNA editing
-post transcriptional editing increases e.g. alternative splicing
increases the number of distinct proteins that can be encoded in a genome
in vivo modification of mRNA
-splitting of mRNA -addition of uridine to mRNA -deletion of uridine from mRNA
in different tissues..
diff alternative splicing will occur
what regulated alternative splicing
repressors and activators e.g. if activator is present then the intron will be spliced
![](https://s3.amazonaws.com/brainscape-prod/system/cm/203/759/116/a_image_thumb.png?1482591521)
miRNA
microRNA -small-non coding RNA molecules -22 nucleotides -function in RNA silencing and post transcriptional regulation of gene expression
![](https://s3.amazonaws.com/brainscape-prod/system/cm/203/759/117/a_image_thumb.png?1482591565)
microRNA role is to
specifically regulate gene expression -key in biological processes such as development, cell birth and death and cancer
how to miRNA regulate gene expression
by blocking translation of specific mRNAs and cause their degradation
RNAi
RNA interference -double stranded -a biological process in which RNA molecules inhibit gene expression or translation, by neutralizing targeted mRNA molecules
![](https://s3.amazonaws.com/brainscape-prod/system/cm/203/759/120/a_image_thumb.png?1482591665)
where are RNAi found in nature
yeast, bacteria, the mouse and fruit fly
model organisms
great for experiments because: share with humans many genes and key biochemical and physiological functions that have been conserved by evolution
andrew fire and craig mellow and their discovery on RNAi
-injecting double stranded RNA reduced expression of specific genes -it does this by reducing levels of mRNA -this RNA interference is sequence specific
siRNA
small interfering RNA