Transcription_Exam 3 Flashcards
Gene expression occurs when info from
DNA exerts effect on cell
What mediates gene expression?
Ribonucleic acid (RNA)
When does gene expression begin?
Begins with transcription
Transcription is very what?
Selective
Types of RNA
rRNA, tRNA, mRNA, miRNA/siRNA, and snRNA
These are found associated with proteins in ribosome (protein factories)
Ribosomal RNA (rRNA)
This carry amino acids during translation (protein synthesis)
Transfer RNA (tRNA)
This encodes amino acid sequence for protein synthesis?
Messenger RNA (mRNA)
This regulatory activity, control gene expression.
Silencing RNA
Splicing introns, small nuclear RNA
snRNA
Both of these, have initiation, elongation and termination
DNA replication and Transcription
DNA replications direction of synthesis is different then transcription? (T/F)
False; it is the same
Only selected genes are transcribed in DNA replication and Transcription. (T/F)
True
Primers are not required for what?
Transcription but is for DNA replication
Genes contain what?
Exons (coding)
Introns (noncoding)
Consensus sequences (noncoding)
Genes are the sequence of what?
Nucleic acids that encode proteins and structural RNA
Thymine (T) is swapped for ____ in RNA
Uracil (U)
Eukaryotic RNA Polymerases: synthesis of pre-ribosomal RNA = precursor to rRNA
RNA Polymerase I
Eukaryotic RNA Polymerases: Syntheses of mRNA, miRNA, snRNA, siRNA. It requires many other proteins to function
RNA Polymerase II
RNA Polymerase II synthesis what?
mRNA, miRNA, snRNA, siRNA
RNA Polymerase III synthesis what?
tRNA
Transcription Initiation does not use
primers
Transcription initiation; RNA polymerase binds to specific DNA sequence called
promoters
Most common promoter sequences:
TATA box
CAAT box
GC box
initiation of transcription (proximal promoter)
TATA box
controls frequency of transcription (distal)
CAAT box
controls frequency of transcription (distal)
GC box
Basal promoters are part of what?
Transcription regulation
Proxima component of basal promoters are that ___ box, and the distal component are what?
TATA box
&
CAAT box or GC box
Basal promoters: The TATA box does what?
Directs RNA polymerase II
Basal promoters: the CAAT box or GC box does what?
Controls frequency of transcription
Response elements of regulated expression?
enhancers or repressors
Regulated expression either ____ or ___ transcription
induce or repress
Regulated expression is found both ___ and ____ from start site
upstream and downstream
Regulated expression can exert an effect from a ___ ____
great distance
What are the steps in RNA synthesis?
Assembly, initiation, elongation, and termination
The assembly of basal transcription complex, the _________ binds to TATA box
TATA-binding protein (TBP)
The assembly of basal transcription complex, transcription factors bind to ____ ____
initiate process
The assembly of basal transcription complex, a ____ strand of ____ is produced
Single, RNA
What is used for approx. 70% of genes (especially ‘housekeeping’ genes - genes required for normal cell functions)
Cytosine-Guanine
Methylation of ____ ___ silences gene
CG islands
What repeated sequence is free of nucleosomes?
Cytosine - Guanine
Free of nucleosomes =
easy to transcribe
Immediately following initiation, the ____ end of RNA is capped with a ____ _____
5’, methyl guanosine
Addition of 5’ cap prevents _____ by exonucleases
degradation
Addition of poly(A) tail contain ______ site near 3’ end of RNA
polyadenylation
Addition of poly(A) tail recognition site for _____ that cleave ___ nucleotides downstream
endonucleases, 20
Addition of poly(A) tail: Poly (A) polymerase can now add ____ ____ nucleotides to end
80-250 adenine
Primary transcript of RNA is large because it contains ____
intron (noncoding region)
Beginning splice site =
GU
Ending splice site =
AG
Intron removal, catalyzed by ____
spliceosome which are made of several small nuclear ribonucleoproteins (snRNPs)
Intron removed and ____ joined together forming mature ____
exons, RNA
