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What does RNA pol I do?
transcribes all rRNA genes except for the 5S rRNA.
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what does RNA pol II do?
synthesizes all mRNAs
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What does RNA pol III do?
Transcribes all tRNA genes and the 5S rRNA gene and small RNAs
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What does RNA pol 1 encode?
rRNA (28S, 5.8S, 18S)
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What does RNA pol II encode?
mRNA
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What does RNA pol III encode ?
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Each eukaryotic RNA polymerase has __ large subunits and ____ smaller subunits
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The two large subunits in eukaryotic polymerases are homologous to the...
E. coli beta and beta prime subunits
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Two smaller subunits of the eukaryotic polymerases are similar to the....
E. coli alpha subunit
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the eukaryotic DNA polymerase does not contain any subunit that performs all of the functions of E. coli ____ factor.
sigma
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In eukaryotic RNA polymerases, The role of bacterial sigma factor is replaced by...
general transcription factors
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List the 4 steps of the process of the DNA intron being spliced out of the mRNA.
- 1) DNA is transcribed to pre-mRNA
- 2) The 7-MG cap is added to the 5' end of the pre-mRNA
- 3) The Poly (A) tail is added to the 3' end
- 4) The intron is spliced out
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Explain how you can get heterochromatin through nucleosome remodelling.
Histones will be wrapped in a DNA strand to create nucleosomes with the help of a repressor complex and the inactivation of the GENE X
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Explain how you get euchromatin by nuclesome remodeling.
nucleosomes are unwrapped from DNA strand with the help of chemically modified histones, while the RNA polymerase with the help of the activated GENE X
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If a histone tail undergoes Lys acetylation, what results?
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Histone tails that undergo Lys/Arg Methylation can result in....
HMT
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Histone tails that undergo Ser/Thr phosphorylation can produce...
kinase/phosphatase
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Epigenetics is...
The study of heritable changes in DNA structure
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What is the transcription cycle?
- Preinitiaition Complex (PIC) assembly (closed)
- Open Complex Fromation
- Initiation
- Promoter Clearance
- Elongation
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The core promoter is relatively...
short
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What does the core promoter consists of?
the TATA box
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What is the important function of the TATA box?
important in determining the precise start point for transcription
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Where is the TATA box located in regard to the start of transcription?
-30 from start of transcription
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The core promoter by itself produces...
a low level of transcription (basal transcription)
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What is basal transcription?
When the core promoter produces a low level of transcription
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Where is the CAT box located in regards to the start of transcription?
-80 from the start of transcription
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The transcriptional start site in eukaryotes is usually an...
adenine
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What factor binds to the BREU and BREd (B recognition Elements)?
TFIIB
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What factor binds to the TATA-box?
TBP
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What factors bind to the INR (initiator)
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What factors bind to DPE (Downstream Promoter Element)?
TFIID
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TTFIID is a complex of proteins that includes ...
- the TATA binding protein (TBP) and
- Several TBP-associated factors (TAFs)
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TFIIB binds to what factor?
TFIID
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What acts as a bridge to bind RNA polymerase II and TFIIF?
TFIIB
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TFIIE and TFIIH bind to...
RNA polymerase II
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TFIIE and TFIIH bind to RNA polymerase II to form..
Preinitiaon complex (Closed Complex)
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TFIIH is a ______ that forms the open complex
helicase
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TFIIH is a helicase that forms....
the open complex
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What factors are released from the RNA polymerase to create the open complex?
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most mature mRNAs have a ________ covalently attached at their 5' end by an unusual 5'-5' phosphodiester bond.
7-methyl guanosine
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most mature mRNAs have a 7-methyl guanosine covalently attached at their __ end by an unusual 5'-5' phosphodiester bond.
5'
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most mature mRNAs have a 7-methyl guanosine covalently attached at their 5' end by an unusual....
5'-5' phosphodiester bond
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What is capping?
The addition of a 7-methyl guanosine covalently attached at their 5' end by s 5'-5' phosphodiester bond.
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When does capping occur?
Capping occurs as the pre-mRNA is being synthesized by RNA pol II
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Usually, capping occurs when the transcript is only ____ to ____ bases long.
20 to 25
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Most mature mRNAs have a string of adenines at the ___ ends
3'
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the 3' end of mature mRNA is called...
polyA tail
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The polyA is not ________ in the gene sequence
encoded
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How is the poly A tail added to mRNA?
Added by an enzyme called polyA polymerase after transcription
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What is the basepair sequence of the polyadenylation sequence?
AAUAAA
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in the addition of PolyA tail to the 3' end of mRNA, endonuclease cleavage occurs about ____ nucleotides downstream from the AAUAAA sequence.
20
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in the addition of PolyA tail to the 3' end of mRNA, endonuclease cleavage occurs about 20 nucleotides ______ from the AAUAAA sequence.
downstream
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in the addition of PolyA tail to the 3' end of mRNA, endonuclease cleavage occurs about downstream nucleotides downstream from the ________ sequence.
AAUAAA
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in the addition of PolyA tail to the 3' end of mRNA, __________ adds adenine nucleotides to the 3' end.
PolyA-polymerase
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in the addition of PolyA tail to the 3' end of mRNA, PolyA-polymerase adds ______ nucleotides to the 3' end.
adenine
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in the addition of PolyA tail to the 3' end of mRNA, PolyA-polymerase adds adenine nucleotides to the __ end
3'
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mRNA sequences that code for protein are called...
exons
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How are exons interrupted?
Intervening sequences (introns)
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What are exons?
mRNA sequences that code for protein
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Transcription by RNAPII produces...
a pre-mRNA
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When a pre-mRNA is produced by transcription by RNAP II, the _____ are later removed from it.
introns
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in the pre-mRNA ______ are connected together or spliced.
exons
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RNA splicing occurs in...
- eukaryotes for all RNAs
- and occasionally in bacteria as well
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What is RNA splicing?
When pre-mRNA is produced when RNAP II transcribes it, and the introns are removed, then the exons are connected together.
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