36 - RNA Synthesis, Processing, & Modification Flashcards
What are the major products of RNA Polymerase II?
a. tRNA
b. rRNA
c. mRNA
c. mRNA
Promote the ability of RNA polymerases to recognize the nucleotide at which initiation begins
a. RNA primase
b. Promoter
c. Helicase
d. DNA ligase
b. Promoter
In eukaryotes, the process of pol II PIC formation required the following EXCEPT
a. polymerase
b. general transcription factors
c. beta subunits
d. transcription factors IIA and B
c. Beta subunits
What protects the 3-prime end of the mRNA?
a. 7-methylguanosine cap
b. poly(A) tail
c. 7-methyladenosine cap
d. poly(U) tail
b. Poly(A) tail
What modulates gene expression?
a. short miRNA
b. short miRNA and siRNA
c. siRNA
d. ncRNA
b. short miRNA and siRNA
In transcription
a. once the enhancer is located, DNA unwinds to expose transcriptions site
b. pyrophosphate is released following each cycle of polymerization
c. the nascent trinucleotide retains the 5-triphosphate of the initiating nucleotide
d. pyrophosphatases degrade the inorganic phosphate providing reversibility of the overall reaction
b. Pyrophosphate is released following each cycle of polymerization
What is a special multicomponent complex involved in converting the primary transcript into mRNA?
a. enhancers
b. ribozymes
c. ribonucleoprotein
d. spliceosome
d. Spliceosome
What are RNA molecules with catalytic activity?
a. enhancers
b. ribozymes
c. ribonucleoprotein
d. spliceosome
b. Ribozymes
Defined as the region of DNA that includes the signals for transcription initiation, elongation, and termination.
a. Transcription unit
b. Primary transcript
c. Transcription start site
a. Transcription unit
They make up the GENETIC CODE
a. RNA synthesis
b. DNA primase
c. Codons
d. Central dogma
c. Codon
For a given gene & gene product, there is a linear relationship between the coding sequence in DNA, the mRNA sequence and, depending on the codon usage, in the () sequence
Protein
The mechanism by which a template strand of DNA is utilized by specific RNA polymerases to generate one of the three different classifications of RNA
RNA synthesis - Transcription
RNAs for protein synthesis
- ribosomal RNA (rRNA)
- messenger RNA (mRNA)
- transfer RNA (tRNA)
RNAs for splicing and modulation of gene expression
MicroRNAs (snRNA and miRNA)
small RNAs
Only protein coding RNA
mRNA
mRNA splicing
snRNA
Modulate gene expression by altering mRNA function
- miRNA
- siRNA
Process where in individual bases in some pre-mRNA molecules are changed; coding information can have changes at the mRNA level by this process
RNA editing
Also called the coding strand because its sequence is identical to those of mRNA (5’ - 3’)
Non-template strand
DNA and RNA synthesis similarities and differences
Signals present within the DNA template that act to stimulate the initiation of transcription - promote the ability of RNA polymerases to recognize the nucleotide for initiation
Promoters
Additional sequence elements are present within the genes that act to enhance polymerase activity even further
Enhancers
Sequences that control gene expression
- transcriptional promoters
- transcriptional enhancers
Enzyme responsible for polymerization of ribonucleotides into a sequence complementary to the template strand
DNA-dependent RNA polymerase
General Process of transcription
- RNA polymerase attaches at the promoter site on the template strand
- Initiation of RNA synthesis at the starting point
- Continued process until termination sequence is reached
Region of DNA that includes the signals for transcription, initiation, elongation, and termination
Transcription unit
(True/False)
Presence of nucleosomes inhibit transcription
True
RNA product which is synthesized in the 5’ to 3’ direction
primary transcript
Regulate promoter activity
Transcription-factor proteins
Regulate promoter activity
Transcription-factor protein
RNA synthesis commences at (1) and begins with the formation of (2)
(1) Transcription starting site (TSS)
(2) initial dinucleotide
Bond that is formed during RNA synthesis until trans termination sequence is reached
Phosphodiester
Another name for the 5’ methyl cap
7-methylguanosine triphosphate cap
(True/False)
5’ methyl cap is added to the 5’ end of mature mRNA at the cytoplasm
False
5’ methyl cap is added to the 5’ end of newly transcribed mRNA precursor in the nucleus prior to the transport of mRNA into the cytoplasm
Modification of mRNA at the 5’ and 3’ ends is for the protection against nucleolytic attack by
5’-3’ exonucleases
Protects the 3’ end of the mRNA
poly(A) tail
special multicomponent complex involved in converting the primary transcript into mRNA
consist of small nuclear ribonucleoprotein particles (snRNPs)
spliceosomes
Composition of spliceosomes
- primary transcript
- five snRNAs (U1, U2, U4, U5, and U6)
- more than 60 proteins with conserved RRM (RNA recognition motifs) and SR (serine-arginine) protein motifs
Transcription phases
- before initiation
- initiation
- elongation
- termination
Sequence properly: (Transcription - before initiation)
1 - Eo promoter DNA complex undergoes a temperature-dependent conformation change to unwind or melt DNA in and around the transcription start site
2 - preinitiation complex is formed (PIC)
3 - RNA polymerase holoenzyme (RNAP-Eo) locates and binds to the promoter
3,1,2
RNA polymerase continues to incorporate nucleotides at which point the polymerase undergoes another conformational change and moves away from the promoter. This reaction is termed -
promoter clearance
The enzyme polymerizes the ribonucleotides in the specific sequence dictated by the template strand and interpreted by what rules
Watson-Citck base-pairing rules
During elongation, what is released following each cycle of polymerization
pyrophosphate (PPi)
() provides access for the appropriate base pairing to the nucleotides of the coding strand
DNA unwinding
RNA polymerase that catalyze the transcription of
(1) rRNA
(2) mRNA & miRNA
(3) tRNA & 5s rRNA
(1) RNA polymerase I
(2) RNA polymerase II
(3) RNA polymerase III
(True/False)
RNA polymerase is responsible for almost all functions in RNA synthesis
True
Fundamental function of RNA synthesis
formation of phosphodiester bond
The degradation of pyrophosphate to () locks the reaction in the direction of RNA synthesis
orthophosphate
(True/False)
All steps of the Central Dogma is subject to modulation and potential sites for gene regulation
True
