gene expression Flashcards
what is meant by the term gene expression
gene is switched on and transcription is happening
what are the different levels that a gene can be regulated
-transcriptional
-post transcriptional
-post translational
what is an example of gene expression at transcription level
(prokaryotes)
lac operon in e.coli bacteria that control the metabolism of lactose, allowing them to use lactose as an energy source when glucose is scarce (saves lots of energy)
what is an operon and why are they useful
An operon is a cluster of genes controlled by a single promoter, allowing for coordinated expression. This system is particularly efficient in prokaryotes for regulating the expression of multiple genes simultaneously.
what does an operon contain
-regulatory gene
-promotor
-operator
-structural genes
what is the role of a regulator gene
codes for a repressor protein that switch on or off structural genes (makes enzyme or not)
what is the role of the promotor
where RNA polymerase binds to transcribe enzymes at structural genes if switched on
what is the role of the operator
acts as an on off switch, repressor protein binds to it to switch structural genes off
what is the role of structural genes
where proteins, enzymes are transcribed
explain the process of gene regulation in e.coli bacteria when lactose is absent
- regulator gene is transcribed and repressor protein is made
2.the repressor protein binds to the operator - this causes RNA polymerase to be unable to bind to promoter region
- meaning RNA polymerase cannot be used to transcribe lactose permease and B- glalactosidase enzymes (that break down lactose) at the structural genes
explain the process of gene regulation if lactose is present in the e.coli bacteria
- regulator gene is transcribe and repressor protein is made
- lactose (acts as an inducer) binds to repressor protein which cause the protein to change shape
- thus repressor protein cannot bind to the operator
- meaning RNA polymerase can bind onto the promotor region
- structural genes are then transcribed and latose permease and B galactosidase enzymes to break lactose down are made
what is a way of regulating gene expression at the transcriptional level in eukaryotes?
Transcription factors
what is a transcription factor
proteins or short bits of non coding RNA that bind to DNA and control which genes are turned on or off.
they can activate or repress transcription of structural genes
transcription factors can be activated by hormones
how many transcription factors are there in eukaryotic cells and how do they work
1500 types
-slide along the DNA molecule seeking and binding to specific promotor regions
-air or inhibit binding of RNA polymerase to activate or suppress transcription
which transcription factors regulate the cell cycle in eukaryotes, what do they do and what disease may be triggered by mutations in one of these?
-proto-oncogenes= produce proteins which speed up cell division
-tumour suppressor genes= produce proteins which slow down cell division
mutations can lead to uncontrolled cell division and potentially cancer
