Easy AF
where is the +1 position in a promoter
at the initiation site
the definition of an open complex
where DNA unwinds and the base pairs are melted producing a bubble
which regions of the sigma factor bind to the -10 and -35 regions respectively
-10: region 2 (2.4 to be exact) and region 3 if there is extended -10 present
-35: region 4 (4.2 to be exact)
where does transcription stop
at the termination site
Which component in a GTF binds to the TATA box?
TBP binds to TATA box
from which nucleotide is transcription mostly initiated
Mostly A but can also be G
definition of a close complex
initiation factors binding to specific region of the promoter gene
What is it indicated that a actively transcribing gene shows a arrowhead-like shape under electron microscope?
shows that DNA contains specific sites at which transcription is terminated
the polymerase is releasing RNA product
Which transcription factor is responsible for the melting of DNA in the core promoter?
TFIIH (H=hurts DNA)
The 5' cap structure in euk. mRNA.
7-methylguanosine joined to 5'-nucleotide via a 5'-5'-triphosphate bridge
what are the 3 phases of transcription
initiation, elongation, and termination
what is absorptive initiation
RNA polymerase synthesizes several short RNAs before entering the elongation phase
what is the significance of RNA association with the template only in few base pairs?
ensures the gene can be transcribed by multiple RNA polymerases at the same time.
What are the 3 major posttranscriptional processing of mRNA in euk.?
1. 5'-capping of mRNA
2. 3'-polyadenylation of mRNA
3. RNA splicing
Which polymerase is used for the polyadenylation & what is the characterisitic of the polymerase?
Pol II : makes a unique tail known as poly (A) tail
what are the 3 types of rRNA
5s, 16s, 23s
definition of frameshift and reading frame
Frameshift: mutatuion caused by deletions or insertions causing the reading frame to be shifted
reading frame: nucleotides are read in sets of 3 to encode a protein
what are the functions of RNA pol 1, 2 , and 3
RNA 1: synthesizes precursors of most rRNAs
RNA 2: synthesizes mRNA precursors
RNA 3: synthesizes precursors of 5S rRNA, tRNA's, and a variety of other small nuclear and cytosolic RNAs
What are the differences between mRNA splicing & mRNA editing?
1. site-specific deamination
2. guide-RNA-directed uridine insertion or deletion
the characteristics of genetic codon
non overlapping, degenerate, tripled code
in what stage does 5'capping occur
during posttranscriptional processing (messenger RNA processing)
what is a nonsense codon (name the 3)
knowns as stop codons bc they stop translation
- UAG, UAA, UGA
Mechanisms of Rho-independent and Rho-dependent terminators.
Rho -independent: Forms a hairpin in the RNA as soon as the region has been transcribed. The hairpin structure disrupts RNA polymerase just as it is transcribing the AT rich stretch... this causes RNA to dissociate from the DNA template.
Rho-dependent: Binds to ssRNA when RNA exits from the polymerase. Rho is directed to a RNA by binding to the rut site and only binds to transcripts that are still being transcribed beyond the end of the gene... not the transcripts being translated. *Has ATPase activity: once attached to the transcript it uses energy derived from ATP hydrolysis to wrest RNA from the template and polymerase.
snRNPs and their functions
snRNPS: small nuclear ribonucleoproteins
1. Recognize the 5' splicing site and branch site through base pairing between snRNAs and snRNPs and the splicing or branch sites.
2. Bring those sites together through RNA-RNA interaction between snRNPs.
3. Catalyze the RNA cleavage and joining reactions.
the common feature of tRNA (there are 6)
1. 5' terminal phosphate group
2. amino acid stem
3. D arm
4. anticodon arm
5. TψC or T arm.
6. 3'-CCA sequence with a free 3'-OH group