DLA 10 Flashcards
What is the function of mRNA?
This RNA encodes the genetic information which will be used to translate into AA
What is the function of tRNA?
brings AA to the ribosome complex
What is the function of rRNA?
combines with ribosomal proteins to form the ribosome
What is the function of snRNA?
combines with certain proteins and is involved in RNA processing and gene regulation in eukaryotes
What is the function of miRNA?
involved in the inhibition of mRNA transcription
Ex: miRNA or siRNA
What is the basic transcription process?
- RNA polymerase will recognize a particular sequence of DNA called the promoter region
- RNA polymerase has helicase activity that will generate a transcription bubble
- RNA polymerase catalyzes the synthesis of an RNA molecule in the 5’ to 3’ direction along the 3’ to 5’ template strand of the DNA
RNA polymerase in prokaryotes?
In bacteria, there is only one single RNA poly.
it is composed of the core polymerase plus sigma factor
What is the role of the sigma factor in a prokaryote RNA poly?
enables the recognition of promoters
What are the three polymerases in eukaryotes?
- RNA poly I
- RNA poly II
- RNA poly III
What are the functions of the three eukaryotic RNA polys?
RNA poly I - 5.8S, 18S, 28S rRNA genes
RNA poly II - all mRNAs and some snRNA and miRNA
RNA poly III - tRNA genes and some snRNA
3 regions of the prokaryotic gene?
- promoter
- RNA coding sequence
- terminator
What does + 1 mean?
That is where transcription starts
Where is the prokaryotic promoter region found in respect to the coding region?
-35 and -10 from the start of the coding strand
What is important about -10 in prokaryotes?
It is where the TATA box is located (pribnow box)
What are the trans elements of eukaryotic transcription?
transcription factors
- TBP
- TFIIA- Facilitates the binding of TBP to the TATA box
- TFIIB- recognizes the initiation site BRE element
- TFIID- Will recognize the TATA box sequence
- TFIIH- contains DNA helicase and activates RNA poly
- TFIIE- will associate with the growing assembly of factors and attracts TFIIH
- TFIIF- stabilizes RNA poly (attracts TFIIH)
main components of DNA synthesis?
- DNA polymerase
- dNTP precursor
- primer required
- A and T
Main components of RNA synthesis?
- RNA polymerase
- NTP precursor
- no primer needed
- A and U
What are the two types of termination in prokaryotes?
- Intrinsic termination
2. extrinsic termination
How is intrinsic termination done?
The palindromic region of the DNA (terminator sequence) a stem loop structure will form. The stem loop structure destabilizes transcription and the transcription proteins will dissociate.
How is extrinsic termination done?
- Rho protein attaches to the recognition site on the RNA
- Rho moves along the RNA following RNA poly
- RNA poly pauses at the terminator and Rho catches up
- Rho unwinds the DNA/RNA hybrid ans separates the RNA from the RNA poly
- RNA poly, Rho, and RNA are released
What kind of protein is Rho?
RNA/DNA helicase
How does termination occur in Eukaryotes?
Termination of the mRNA sequence is directly linked directly with the process of poly-adenylation (poly A tail)
The 3 prime end of the mRNA is cleaved by cleaving factors. This separates the RNA from the RNA/DNA hybrid. this leads to termination
poly A tail is added to the 3 prime end
Explain rifampin/ rifampicin?
an antibiotic from streptomyces
inhibits the start of transcription
blocks formation of first phosphodiester bond by binding to RNA poly
Eukaryote poly not impacted
used to treat tuberculosis
alpha- amanitin?
found in the death cap mushroom and is an inhibitor of RNA poly II (transcribes mRNAs)
Explain Actinomycin D?
binds tightly to double stranded DNA
inhibits both transcription and replication in both eukaryotes and prokaryotes
normally used as an anti-cancer drug not an antibiotic
What do courmarins and quinolones do?
They inhibit bacterial gyrase, thus supercoiling cannot be corrected.
antibiotic that is effective
