Lecture 12: Gene Expression Flashcards
How do we regulate gene expression in bacterial cells (prokaryotic)
lac operons
What are the two kinds of operons in prokaryotic cells
-inducible: the transcription is usually off but can be stimulated
-repressible: the transcription is usually on but can be inhibited (repressed)
What type of operon is the lac operon
repressed off
When is the lac operon on? When it is off?
On: lactose only present
Off: glucose only present
off: both glucose and lactose are present
What happens when glucose is present?
it inhibits adenylyl cyclase, no cAMP, cannot form CAP/cAMP complex, cannot initiate transcription
What happens when lactose is present?
a small amount of allolactose is produced that binds to the repressor and prevents it from binding to the operator
In terms of eukaryotic cells:
What are the two types of regulatory molecules?
-Cis acting elements, part of the DNA
-Trans acting elements: proteins and transcription factors
What are the streps of transcriptional regulation by steroid hormones
- binding of a steroid hormone to its nuclear receptor which causes a conformational change in the receptor that uncovers its zinc finger. DNA binding domain
- the hormone receptor complex interacts with specific regulatory DNA sequence such as GRE
- The hormone receptor complex in association with coactivator proteins control the trans scripting of target genes
What is alternative splicing
a cellular process in which exons from the same gene are joined in different combinations, leading to different, but related, mRNA transcripts
ex: 1, 2, 3, 4, 5 or 1, 2, 4, 5
What is an example of alternative splicing in the body
tropomyosin having different forms in different tissues
____________ a widespread and conserved regulatory mechanism that generates diverse 3′ ends on mRNA
Alternative polyadenylation (APA)
What is an example of Alternative polyadenylation in body
production of two different IG molecules: membrane bound IgM and IgD
__________: modification in which 1 base in the mRNA is altered
Give an example
mRNA editing
Example: liver and small intestine cell produce apBs of different lengths
What is an example of mRNA stability
regulation of transferring receptor protein TfR expression by iron
RNA interference is the Mechanism of reducing gene expression by either: (2 things)
‣ repressing translation
‣ increasing the degradation of specific mRNAs
