RNA Structure and Transcription Flashcards
What is the process by which DNA is converted to any form of RNA?
Transcription
What are the four major types of RNA?
Messenger RNA, Transfer RNA, Ribosomal RNA, MicroRNA
What is the most heterogenous type of RNA in size and base seqeunce composition?
mRNA
What form of mRNA carries informatino from >1 gene?
Polycistronic
What is the function of the 5’ UTR?
It regulates and directs translation
What is the function of 3’ UTR?
Needed for mRNA stability and regulation by mRNA
What type of RNA has extensive interchain base pairing that creates a characteristic clover-leaf structure?
tRNA
What type of RNA serves as an adaptor molecule to bring a specific amino acid to a growing peptide?
tRNA
Where on a tRNA molecule is the amino acid bound?
3’ end
What part of the tRNA molecule binds to mRNA?
Anticodon
What is the term for catalytically active RNA?
ribozyme
How many different sizes of rRNA are in prokaryotes? Eukaryotes?
3; 4
What type of RNA is most abundant in the cell?
rRNA
To which DNA sequences do RNA polymerases bing?
The promoter
In which direction does RNA synthesis occur?
5’–> 3’
What molecules serves as the bases in RNA synthesis?
Ribonucleotides
What is the relationship of an mRNA transcript to the template strand and coding strand?
Complementary to the template strand and identical to the coding strand
How many prokaryotic RNA Polymerases are there?
1
How does prokaryotic RNA Polymerase recognize DNA?
Sigma factor
Where does the enzymatic activity of RNA Polymerase occur?
In the “core enzyme”
What are the stages of transcription
Initiation, Elongation, Termination
What consensus sequences are located in the prokaryotic promotor region?
-35 sequence and -10 sequence (Pribnow Box)
What enzyme unwinds DNA during transcription?
RNA Polymerase
What are abortive transcripts?
Several short pieces of RNA generated in the initation of RNA transcription that ensures the proper location of RNA polymerase
At what point is sigma factor released from the core enzyme of RNA polymerase?
Once growing RNA exceeds 10 bases and elongation begins
What are the two basic forms of prokaryotic transcription termination?
Rho- independent and dependent termination
Which form of prokaryotic transcription termination involves the formation of a hairpin structure?
Rho-independent termination
What characteristic of an RNA sequence allows for the formation of a stem-loop structure?
Dyad symmetry
What base is found in a series of 8-10 residues in an mRNA transcript utilizing Rho-independent termination?
Uracil
What type of prokaryotic transcription termination utilizes energy?
Rho-dependent termination
What kind of protein is Rho?
A hexameric adenosine triphosphatase (ATPase) with helicase activity
What process is inhibited by Rifampicin?
Transcription Initiation
What is Rifampicin’s mechanism of action?
Binds to beta subunit of RNA Pol holoenzyme , inbiting the formation of the first phosphodiester bond
What process is inhibited by Dactinomycin?
Transcription Elongation
What is Dactinomycin’s mechanism of action?
Interacts with DNA at the transcriptio initiation complex
How many eukaryotic RNA polymerases are there?
3
What are the functions of the three eukaryotic RNA Polymerases?
RNA Pol I- transcribes rRNA; RNA Pol II- transcribes mRNA; RNA Pol III- transcribes tRNA and snRNA
What consensus sequences are located in the eukaryotic promoter region?
CAAT box (~-70- -80); TATA (Hogness) box (~-25)
What allows RNA Pol II to recognize and bind to DNA?
General transcription factors
What is the term for any factor, protein, or element that is independent of the promoter or gene being regulated?
Trans-acting element
What is the term for any element that is an integral part of the promoter or gene being regulated?
Cis-acting element
What is the name of eukaryotic cis-acting non promoter elements that help activate or repress transcription
Enhancers
What is the mechanism of activation/ repression by enhancers?
Enhancers bind additional, specific transcription factors and through DNA looping or bending, they then interact with the transcription initiation complex
What is the process by which DNA is interconverted from the closed heterochromatic form to the actively transcribed euchromatic forms?
Chromatin Remodeling
What is the mechamism of alpha-aminitin?
Binds specifically to RNA Pol II and inhibits its ability to process along the DNA
