Transcription and Transcriptional Regulation Flashcards
(52 cards)
What are some uses of PCR?
- detection of infectious organisms – such as microbes and viruses
- forensics and disease diagnosis
- detection of gene expression (RT-PCR)
- protein engineering and DNA analysis
What determines the ends of the product of PCR?
The 5’ ends of the primer used
Northern blotting steps
- isolate total RNA
- denature and separate RNA
by electrophoresis - transfer to membrane
- Detect using labeled (radioactive)
antisense probe to hybridize
TBP:
TATA-box Binding Protein, eukaryotes
What does TFIIH do?
acts as both a DNA helicase and a kinase
during initiation
Does an RNA strand have to be completely made before a new one is started?
No. The synthesis of additional RNA molecules can be started before previous RNA molecules are completed
Does RNA polymerase need a primer?
No.
What is the proofreading mechanism of RNA polymerase?
If an incorrect nucleotide is added to the growing RNA chain, the polymerase can back up, and the active site of the enzyme can perform an excision reaction that resembles the reverse of the polymerization reaction, except that a water molecule replaces the pyrophosphate and a nucleoside monophosphate is released.
snRNAs
small nuclear RNAs, function in a variety of nuclear processes, including the splicing of pre-mRNA
What is the sigma factor?
a subunit that associates with the RNA core enzyme and assists in beginning DNA transcription in prokaryotes. bind specific promoter elements
transcription bubble
the region of unpaired DNA which is stabilized by the binding of the sigma factor to unpaired bases on one of the exposed strands
How is transcription terminated in prokaryotes?
string of A-T nucleotide pairs which fold into a hairpin. The formation of the hairpin helps to disengage the RNA transcript from the active site.
Are all termination sequences the same?
no, there is variation, as long as they form hairpins its chill
If an RNA sequence is 5’-GUGUACACAU-3’, what is the sequence of its DNA template?
5’-ATGTGTACAC-3’
The strand in dsDNA used as a template for RNA synthesis depends on:
the orientation of the promoter
The majority of RNA transcripts in cells are _____ and predominately _____
The majority of RNA transcripts in cells are noncoding RNAs and predominately rRNA
Which of the eukaryotic RNA polymerases is responsible for mRNA synthesis?
RNA polymerase II
Which is more accurate, DNA or RNA polymerase?
DNA polymerase
Which is more processive, DNA or RNA polymerase?
RNA polymerase
Genes that are expressed in practically all cells in the human body include:
tRNAs
RNA polymerase
histones
ribosomal proteins
Restriction nucleases cut
DNA at specific sequences
Main differences between RNA polymerase II and bacterial RNA polymerase
1) While bacterial RNA polymerase requires only a single transcription initiation factor (sigma) to begin transcription, eukaryotic RNA polymerases require many such factors, collectively called the general trasncription factors
2) Eukaryotic transcription initiation must take place on DNA that is packaged into nucleosomes and higher-order forms of chromatin structure, features that are absent from bacterial chromosomes
How far is the TATA box from the transcription start site?
What binds to it?
About 25 nucleosides upstream from the transcription start site
TFIID
What are transcriptional activators?
gene regulatory proteins that bind to specific DNA sequences to help attract RNA polymerase II to the start point of transcription
