W1- Lecture 4.1- Molecular Bio Of The Gene Flashcards
Why do we need introns ?
For organism plasticity
+ control of gene expression
Name a species that turning on and off parts of the gene is important in embryo development
Drosphila melanogaster
How does a cell keep control over which genes are expressed or not?
The primary regulatory feature is the promotors region
What need to bind to the promoter region for a gene to be expressed ?
Transcriptional factors
Aside from transcription factors what else can bind to promote expression in a gene.
+ where
Other DNA-binding proteins to
Upstream enchanter sequences
What is the driving force of gene expression
RNA polymerase 2
Name there three types of RNA polymerase
RNA polymerase I
RNA polymerase II
RNA polymerase III
Describe the roles
RNA polymerase I
RNA polymerase II
RNA polymerase III
RNA polymerase I - production of the large ribosomal RNA
RNA polymerase II – production of mRNA
RNA polymerase III – production of tRNA and the small ribosomal RNA molecules
Where on the DNA sequence does RNA polymerase bind ?
TATA sequence / TATA box
Thymine adenosine Thymine adenosine sequence
Describe how transcription takes place
RNA polymerase +TATA box
RNA polymerase opens up dna creating replication fork
One strand acts as a template for RNA free floating nucleotides
Which direction does RNA polymerase act ?
5’ to 3’
What causes a gene to be turned off ?
Transcriptional repressors
What does the transcriptional repression interact with ?
How?
The activator
Binding site next to the activator
-blocks function
Or
overlapping the binding site (stops activator from binding)
Describe the act of the transcriptional repressor in causing the Wilm’s tumour protein
WT protein
In the developing kidney
WT protein + promotor region of the EGR-1 gene (transcriptional activator) which switched off expression
If the gene incoming WT protein WT1 is mutated it leads to uncontrolled expression of EGR-1
Developments of kidney tumours
WT1 is a tumour suppressor gene
Basically WT and EGR Cancels each other so more erg less wt hence more tumour
What molecules is mRNA capped by at the 5’ end during transcription ?
methylated G nucleotide
GMP
methyl group
