RNA Structure, synthesis and Processing Flashcards
The space between the start codon and the stop codon is called
The open reading frame
Transcription is highly selective. True/False
True
More than 2% of genome encodes for proteins. True/False
False
(Only 2% encodes for proteins)
What is the complete set of RNA transcripts expressed by a genome?
Transcriptome
In which part of the cell are microRNA’s found
The cytoplasm
What type of RNA makes up 80% of the total RNA in the cell
rRNA
RNA with catalytic activity is termed as
Ribozyme
Which RNA is the smaller of the three major types of RNA?
tRNA
All mRNA’s code for only a single protein and therefore are called
Monocistronic
What kind of mRNA is characteristic of prokaryotes
Polycistronic mRNA
What kind of mRNA is characteristic of eukaryotes
Monocistronic mRNA
An mRNA carrying information from only one gene is
monocistronic
An mRNA carrying information from more than one gene is
polycistronic
What cap is attached to the 5’ end of mRNA
7-methylguanosine
What unusual linkage is between 7-methylguanosine and the 5’ end of the mRNA
5’ to 5’ triphosphate linkage
In bacteria, one species of RNA pol synthesizes all of RNA. True or false
True
What enzyme synthesizes RNA primers in prokaryotes
Primase
Name the two types of enzymes RNA pol is made up of
The core enzyme
The holoenzyme
The core enzyme is able to recognize the promoter region and the holoenzyme is not. True/False
False
The holoenzyme is able to recognize the promoter region due to the presence of sigma factor
The most important or predominating sigma factor is
Sigma 70
What other activity does the sigma factor have apart from recognizing the promoter region
Helicase activity
Why is the sigma factor also known as house keeping genes
Because they are essential for the survival of the bacteria
Function of DNA topoisomerase
Unwinding of supercoils in DNA
In what direction is transcription?
5’ to 3’ direction
RNA polymerase does not require a primer. True/False
True
RNA polymerase has a 3’ to 5’ exonuclease domain for proofreading. True/False
False
RNA polymerase does not have a 3’ to 5’ exonuclease activity
The two types of transcription termination in bacteria
a. Rho dependent
b. Rho independent
What is formed during Rho-independent termination
Hairpin
What protein is added to the 5’ end of the nascent RNA during Rho dependent termination?
Rho
What drug is efficient in treating tuberculosis?
Rifampincin
What makes Rifampincin so efficient?
It prevents chain growth beyond three nucleotides
That is, it inhibits transcription
Which RNA polymerase is important in transcription in eukaryotes
RNA polymerase 2
What general transcription factor recognizes the TATA box in eukaryotic transcription
TFIID ( transcription factor 2 D)
What general transcription factor brings the polymerase to the promoter
TFIIF
The helicase activity of which general transcription factor melts the DNA to form transcription bubble
TFIIH
TFIIH has a kinase activity.True/False
True
Which transcriptional factor regulates which genes are expressed at a given point in time
Specific transcriptional factors
Variety of motifs through which transcriptional activators or specific transcriptional factors bind to DNA include
Helix-loop-helix
Zinc finger
Leucine zipper
Helix-turn-helix
Mutation of Zn finger motif results in what type of Tumor
Wilms Tumor-1
What is the role of enhancers in eukaryotic transcription?
They increase the rate of initiation of transcription by RNA pol 2
Name the RNA polymerase 2 inhibitor
Alpha- amanitin
In the processing of pre-rRNA exons are methylated. True/False
True
In tRNA processing, an intron is removed from anticodon loop by
Nucleases
In tRNA processing, the 5’ end is trimmed by what ribozyme
RNase P
In tRNA processing, the 3’ end is trimmed by which ribozyme?
RNase D
In tRNA processing, the addition of the sequence ‘CCA’ at the 3’ end is done by
Nucleotidyltransferase
What enzyme adds poly-A tail to the 3’ end?
Polyadenylate [poly(A)] polymerase
The process of removing and joining exons is called
Splicing
What two sequential transesterifications proceed splicing
lariat formation
Exon joining
This refers to the different ways of shuffling or joining exons together
Alternative splicing
What is the polyadenylation signal sequence prior to the addition of the poly-A tail
AAUAAA
In eukaryotes gene expression is also controlled at postrranslational and posttranscriptional processes. True/False
True
Enhancer-Activated transcription often requires the presence of a
Coactivator
