Lecture 13 Flashcards
What are Related genes?
These are genes that are located at different loci but are regulated by the same transcription factor which recruits RNA Pol II for transcription.
Which RNAs is Pol I responsible for transcribing and what are they components of?
Pre-rRNAs which include: 28s, 18s, 5.8s, and they are key components of ribosomes and facilitate protein synth.
RNA Pol II is responsible for a wide range of RNAs, including __RNA which encodes protein, __RNA which are key components of spliceosomes, __RNA which carries out translational control, and __RNA which is responsible for silencing RNA.
RNA Pol II is responsible for a wide range of RNAs, including: mRNA (encodes protein), snRNA (RNA splicing), miRNA (Translation control), and siRNA (Chromatin-mediated repression/translation control.)
What is alpha-amanitin and what does it do?
Alpha-amanitin is a fungal toxin that blocks RNA Pol II
RNA Pol III transcribes __RNA (a key component of protein synth), __sRNA (a small ribosomal component), __sRNA (a part of the SRP that facilitates insertion of polypeptides into the ER), and __RNA U6 (spliceosome component.)
RNA Pol III is responsible for tRNA (protein synth), 5sRNA (ribosomal component/protein synth), 7sRNA (signal recognition particle for insertion of polypeptides into the ER), snRNA U6 (comprise spliceosome.)
What is the difference between a “cis-acting” element and a “trans-acting” element?
Cis-acting means that the element in reference is part of the thing it acts/facilitates action on (typically specific DNA sequences that act as signals for DNA Pols), whereas a trans-acting refers to elements that travel to the thing they act/facilitate action on (typically transcription factors.)
What are the DNA sequences that recruit transcription factors?
Big one is the TATA box, located about 25 NTs downstream from the start site, still in the “core promoter region.” The others include the CAAT box, the GC box, and Enhancer element.
Which proteins bind the TATA box, the CAAT box, the GC box, and the Enhancer element?
TFIID binds the TATA, CTF binds the CAAT, SP1 binds the GC, and a variety of STFs bind the Enahncer element.
What is it that determines where and when an RNA Pol will bind and transcribe?
It is a combination of specific DNA sequences and specific transcription factors that determine this.
Transcription factors bind the DNA and create a pre-initiation complex beginning with which binding protein, and what does that protein do to the DNA?
This process begins with the TATA binding protein (TBP), which bends the DNA and begins a sort of pre-initiation cascade.
Where can an Enhancer element be found on the DNA relative to the coding region and what is the name given to proteins that bind the Enhancer?
It could be upstream or downstream and could be even as far as thousands of NTs away. They are bound by “Activators.”
You know how steroid hormones regulate transcription, but how do other ligands, like those that activate AC and PKA cascades regulate it?
cAMP from AC activates PKA by separating its catalytic subunit –> this subunit travels into nucleus and phosphorylates CREB –> phophorylated CREB binds DNA –> CBP binds DNA-bound CREB –> this complex recruits transcription factors and RNA Pol II.
What is the cause for Rubinstein-Taybi syndrome and what does the fact that this syndrome results in multiple abnormalities across different tissue types tell you about the importance of the protein that is mutated in this syndrome?
It is caused by a mutation in CBP, and the fact that multiple tissue types are affected tells you that CBP is necessary for transcription in many tissue types.
What is a cause for Aniridia?
Deficiency in transcription factor PAX6 can lead to issues with the formation of the iris (it doesn’t form, which is what’s termed “aniridia.”
How does epigenetics come into play for transcription regulation?
Recruitment of transcription factors and RNA Pol II requires the right histone modification patterns at the promoter. (i.e. Acetylation helps promote transcription whereas Methylation does the opposite.)
