Chapter 12 - Gene Transcription and RNA Modification Flashcards
What is the first step of gene expression?
It is transcription.
What is transcrition?
It refers to the copying of DNA sequence into RNA sequence.
What is protein encoding genes?
encodes the amino acid sequences or polypeptides.
What does the transcription of gene coding protein?
It produces mRNA.
What is promoters?
They are DNA sequence that promote gene expression and direct the exact location for the initiation of transcription.
Whare is the location of promoters?
They are typically located upstream of the site where the transcription begins.
What is the most common promoter sequence is called?
It is called the consensus sequence.
What is the function of RNA polymerase?
It is an enzyme that catalyzes the synthesis of RNA.
What can RNA polymerase captures?
It can only captures sigma factors.
What is the region of sigma factor that is tightly bounded to the DNA?
It is called helix turn helix structure.
What does the sigma factor recognizes?
It recognized the -35 and -10 sequence of the promoter.
Where does sigma factor bind?
It binds at the promoter region.
How long is the open complex?
It is about 17 base pair long.
what is the rate of RNA synthesis?
It is 43 nucleotide base per second.
When does the termination occurs?
It occurs when the RNA-DNA hybrid of the open complex is forced to separate.
What are the two different mechanism for termination?
- rho dependent termination
2. rho independent termination
What is the recognition site of rho protein?
It is rut recognition site.
Where does rho protein bind to ?
It binds at the rut recognition site in the RNA.
What does rho independent termination mechanism depends on?
It depends on two sequence. 1. the uracil rich region at the 3 prime end of RNA
2. stem loop structure upstream of the uracil rich sequence.
Why eukaryotic gene transcription is more complex?
Because there are:
- larger more complex cells.
- more genes
- multicellularity which adds higher level of regulation.
What does RNA pol I does?
It transcribes all rRNA genes.
What does RNA pol II does?
It transcribes all protein encoding genes.
What does RNA pol III does?
- It transcribes all the tRNA genes.
- 5sRNA
- Micro RNA genes.
How long is the core promoter?
It is relatively short.
What does the core promoter consists of?
It consists of TATA box and transcription start site.
What is the function of the core promoter?
It determines the precise start point of transcription.
What is the basal transcrition?
It is the lowest level of transcription in the core promoter.
What is the regulatory elements?
They are DNA sequences that affect the binding of RNA polymerase to the core promoter.
What is the transcription factors?
They are protein that bind to the elements and influence the rate of transcription.
What are the two different type of regulatory elements?
- enhancers
2. silencers.
What are the three categorize of proteins that must be at the core promoter for transcription to occur?
- RNA pol II
- general transcription factors ( 5 proteins)
- Protein complexes called mediator.
What is the mediator?
It is protein complexes.
What are the two models of termination in eukaryotes?
- Allosteric model
2. Torpedo model.
When does the termination occur in Eukaryote cells?
It occurs 500 to 2000 nucleotide after the polyA tail.
How is RNA strands get modified?
- splicing
- polyA tail
- 5 capping
To what end the 5 capping is added?
It is added to the 5 prime end.
To what end the polyA tail is added?
It is added to the 3 prime end.
What is the role of 5 capping?
- It moves RNA outside the nucleus.
2. It constitute early stages for translation.
What are the three different splicing mechanism?
- spliceosome
- group 1 intron splicing
- group 2 intron splicing
What is the function of exonucleases?
cleave a covalent bond between two nucleotide at one end.
What is the function of endonuclease?
It cleaves bond within the strand.
