Flashcards in Transcription, RNA Processing and Control of Gene Expression Deck (25)
What are three important differences between RNA and DNA?
1) RNA is single-stranded
2) RNA has uracil instead of thymine
3) RNA contains ribose instead of deoxyribose
What are the nucleotide donors for RNA?
ATP, GTP, UTP, CTP
Which polymerase is associated with rRNAs?
mainly Pol I, some Pol III
Which polymerase is associated with tRNAs?
Which polymerase is associated with mRNAs?
How does alpha-amanitin work?
Death cap mushroom
- potent inhibitor of Pol II, which blocks synthesis of mRNAs
Which type of RNA is the most abundant?
How can rifampicin kill certain bacteria but have low toxicity against humans?
It is a potent inhibitor of RNA polymerase found in bacteria, therefore do not affect eukaryotic Pol II
What are the three modifications needed in order for mRNA to leave the nucleus?
In this specific order:
1) 5' methylguanosine cap
2) splicing, leaving only exons
3) poly-A tail
These processes mark the mRNA 'mature' and ready for transport out of the nucleus
Which disease is result of incorrect splicing, caused by a mutation in the gene that altered the nucleotide sequence at the first exon/intron boundary resulting in the destruction of the consensus sequence required for correct splicing?
Which disease is a result of a mutation that caused a single base change in the 5' splice donor site of one particular intron leading to defective splicing and production of a truncated protein that lacks one exon, which gets rapidly degraded?
Which type of histone modification acetylates lysine residues in histones and what does it result?
HATs (histone acetyltransferases)
- loosens up the DNA/histone modification
- facilitates transcription
Which type of histone modification deacetylates lysine residues in histones and what does it result?
HDACs (histone deacetyltransferases)
- tightens up DNA/histone modification
- inhibits transcription
In which base does DNA methylation occur?
What are large protein complexes that use the energy from ATP hydrolysis to change nucleosome structure temporarily to pack DNA more tightly to the histone core or unpack so the DNA is more accessible?
chromatin remodeling complexes
Where do DNA-binding proteins bind to regulate transcription?
Example of a helix-turn-helix protein
What an example of zinc finger proteins?
What's an example of leucine zipper proteins?
Fos and Jun
Where are cortisol receptors normally hang out at?
The glucocorticoid receptor enters the nucleus as what structure once its's been activated by its ligand cortisol?
Once the homodimer glucocorticoid receptor have formed, how does it regulate transcription once it enters the nucleus?
It is a zinc finger protein and binds to DNA at GRE (glucocorticoid responseive element) region and recruits HAT to facilitate transcription
Which cellular compartment are thyroid hormone receptors found?
How does the thyroid hormone receptor act as a repressor?
- the receptor exist as a heterodimer (thyroid hormone receptor + retinoid X receptor)
- in the absence of thyroid hormone, the receptor recruits HDAC that represses transcription