LEC: UNIT 9 Flashcards
In eukaryotes, transcription occurs in the _____
nucleus
DNA-dependent RNA polymerase synthesizes in what direction?
5’-to-3’
T/F: only the ATP and GTP requires RNA polymerase
F. all ATP, GTP, CTP, and UTP does
T/F. DNA-dependent RNA polymerase does not require a primer for its RNA synthesis
T
T/F. Bacterial DNA-dependent RNA polymerase is a multi-subunit enzymes
T
The __ factor has an important role in the recognition of the promoter
σ
What is the role of the promoter?
DNA sequence that provide direction for RNA polymerase; directs the core complex to specific binding sites on the DNA
The DNA-dependent RNA polymerase is made up of ___ (how many) core subunits aside from the σ factor?
5 (total of 6 subunits)
serves as the template for RNA synthesis
Template (antisense) strand
identical to the RNA transcribed from the gene, with U in the RNA in place of T in DNA
Coding (nontemplate/sense) strand
____ (polymerase) binds to and transcribes only the template strand
RNA polymerase
3 phases of transcription
Initiation
Elongation
Termination
Promoter regions in prokaryotes (4)
- Pribnow Box /
- -10 region
- -35 region
- UP element
Identify the phase of transcription: Recognition of promoter region by σ factor (closed promoter complex)
Initiation
Identify the phase of transcription: RNA polymerase bind to DNA
Initiation
Identify the phase of transcription: Unwinding of the DNA (open promoter complex)
Initiation
Identify the phase of transcription: Addition of purine ribonucleotide triphosphate as the first base of RNA transcript.
Elongation
Identify the phase of transcription: RNA polymerase initiates mRNA synthesis
Elongation
Identify the phase of transcription: Dissociation of σ factor
Elongation
Identify the phase of transcription: includes ρ-Dependent Mechanism and aρ-Independent Mechanism
Termination
Identify the type of termination: extrinsic termination
ρ-Dependent Mechanism
Identify the type of termination: intrinsic termination
aρ-Independent Mechanism
Identify the type of termination: ρ factor recognizes the termination region; It weakens the interaction between the template and the transcript.
ρ-Dependent Mechanism
Identify the type of termination: It is controlled by specific sequences, termination sites (contains palindromes in the template strand).
aρ-Independent Mechanism
In aρ-Independent Mechanism , the newly synthesized RNA form a “_____” (appearance) loop
“Hairpin”
RNA polymerase II consists of ___ (how many) subunits
12 (RBP1-RBP12)
Compartment of RNA polymerase I
Nucleolus
Compartment of RNA polymerase II
Nucleoplasm
Compartment of RNA polymerase III
Nucleoplasm
T/F: Mammalian cells possess five distinct nuclear RNA polymerases
F. They only possess THREE
Prokaryotic mRNAs are synthesized on the bacterial ____ in direct contact with the ____ and are immediately available for translation.
nucleoid, cytosol
What happens during the post-transcriptional modifications in the processing of eukaryotic mRNAs?
o Addition of 5’ capping
o Splicing of introns
o Polyadenylation of 3’ tail
What happens during the capping of eukaryotic mRNA?
- Addition of GMP in an inverted orientation by guanylyl transferase
- Methylation of C7 at G by guanin methyltranferase
Functions of 5’ cap
o Prevents 5’ end from being digested
o Aids in the transport of mRNA out of the nucleus
o Plays a role in the initiation of mRNA translation
Identify the event: eukaryote genes frequently contain intervening base sequence that do not appear in the final mRNA of that gene product
Splicing of introns
Expressed DNA sequence are called _____
exons
Intervening DNA sequences that are not expressed are called _____
introns
During the splicing reaction, when the exons are spliced together, a _____ forms in the intron
lariat
Identify the event: exons are separated by intervening intron
the splicing reaction
_____ is made up of snRNAs associated with snRNPs
Spliceosome
This tail protects the mRNA from nucleases and phosphatases
polyadenylate “tail”
A polyadenylate “tail” that is usually 100-200 nucleotides long, is added to the __’ (5’ or 3’) end before the mRNA leaves the nucleus.
3’
Difference in the template of transcription and replication
Transcription: 3’»_space;> 5’
Replication: 5’»_space;> 3’; 3’»_space;> 5’
Which requires primer? (Transcription or replication)
Replication
