Ch 15 Regulation Of Gene Expression Flashcards
In operon, where does RNA polymerase bind
Promoter Regino of the DNA
What does the lac operon produce when the repressor is inactive
Lactase
The Trp operon is a ____ operon and is example of ___ genes
Repressible, negative
What is the natural state of Trp operon and in what from is its repressor synthesized
ON, inactive
When does cAMP accumulate in the cell?
When glucose is scarce
The on off switch is a segment of DNA called
Operator
Genes whose expression is turned off in response to a substance in the environment are
Repressible genes ( on by default)
Genes whose expression is turned on in response to a substance in the environment are known as
Inducible genes (off by default)
What is the name of the stethoscope of DNA where RNA polymerase binds?
Promoter
What is the name given to a protein that binds to the operator and blocks RNA polymerase
Repressor
In addition to responding to the presence or the absence of lactose, the lac operon is also sensitive to glucose levels. In the presence of high amounts of glucose
cAMP is produced and attaches to the CAP protein allowing it to bind to the CAP site resulting in high levels of gene expression
In addition to responding to the presence or absence of lactose, the lac operon is also sensitive to glucose levels in the presence of low amounts of glucose
No cAMP is made an the CAP protein will not bind to the CAP site, leading to low levels of gene expression
A geneticist isolates a gene for the trait X in mice. He also isolates the corresponding mRNA derived from this mouse gene. He notices that the mRNA contains 1,535 less nucleotide bases than the DNA isolate. Did the geneticist isolate the wrong segment of DNA?
No the final mRNA contains only exons. The introns were removed during mRNA splicing
Key components of an operon
-promoter: site where RNA pol can bind
* Operator : repressor proteins bind to regulate transcription
* structural genes: genes within the operon that code for the desired proteins
Guide RNA
Guide RNA: sequence which acts as a GPS guiding Cas9 enzyme to specific location. Change an organisms DNA: first select which DNA sequence you’d like to modify, synthesize guide RNA with a sequence complements to the target DNA, take guide RNA and Cas9 into organisms cells, Cas9 then uses guide RNA to find where its needed to cut into the DNA sequence which then the enzyme cuts the DNA at specific site creating a double strand break - this process is called CRISPR - Cas9 gene editing
What’s cas9, its function, how its used for cell defense
Produced by CRISPR, Cas 9 is a type of enzyme which binds to the DNA and after cuts off the specific regions of DNA. It’s useful bc it can create a site specific DNA which helps develop an adaptive immune resistance to viruses.
Difference between prokaryotes and eukaryotes gene regulation
Eukaryotes have a nucleus whch makes the processes of transcription and translation separate, resulting in control of gene expression at multiple levels when prokaryotes where regulation mostly happens at transcription level bc lack of nucleus and free floating DNA in cytoplasm
Transcription factors in prokaryotes and eukaryotes
Transcription factors - Prokaryotes: use sigma factors ( specific proteins that guide RNA pol to promoter) regulations involve repressors and activators that bind near the promoter. Lacks general transcription factors. Eukaryotes: use general transcription factors like TFID, TFIIB to assemble at promoter and form the transcription initiation complex
Co -Activators andd mediators
Co -Activators andd mediators - prokaryotes: rarely use it, transcription regulation is relatively direct, with proteins interacting closely with RNA polymerase
Eukaryotes: Involve co activators and the mediator complex, which bridge specific transcription factors and RNA pol2 facilitating transcription initiation
