Transcription Flashcards
The synthesis of RNA molecules using DNA strands as the templates so that the genetic information can be transferred from DNA to RNA.
Transcription
code for proteins
mRNAs
form the basic structure of the ribosome and catalyze protein synthesis
rRNAs
central to protein synthesis as the adaptors between mRNA and amino acids
tRNAs
Serves as the template for the telomerase enzyme that extends the ends of chromosomes
Telomerase RNA
Function in a variety of nuclear processes including the splicing of pre-mRNA
snRNAs (small nuclear RNAs)
Help to process and chemically modify rRNAs
snoRNAs (small nucleolar RNAs)
________________, not all of which appear to have a function; some serve as scaffolds and regulate diverse cell processes, including X-chromosome inactivation
lncRNAs (long noncoding RNAs)
Regulate gene expression by blocking expression of specific mRNAs and causing their degradation
miRNAs (microRNAs)
Turn off gene expression by directing the degradation of selective mRNAs and helping to establish repressive chromatin structures
siRNAs (small interfering RNAs)
Bind to piwi proteins and protect the germ line from transposable elements
piRNAs (Piwi-interacting RNAs)
DNA regions that can be transcribed (includes promoter, operator, and structural genes)
Operon
Is the strand from which the RNA is actually transcribed
Template strand (antisense strand)
Is the strand whose base sequence specifies the amino acid sequence of the encoded protein.
Coding strand (sense strand)
*The enzyme responsible for the RNA synthesis
RNA Polymerase
What factor binds to the core RNA polymerase to become an RNA polymerase holoenzyme
Sigma factor (σ)
In E. coli is consists of 5 different subunits:
α2 = Determine the DNA to be transcribed
β = Catalyze polymerization
β’ = Bind & open DNA template
ω = Non-essential smallest subunit that facilitates the assembly of RNA polymerase
σ = Recognize the promoter for synthesis initiation
*Drug for tuberculosis, can bind specifically to the β subunit of RNA-pol and inhibit the RNA synthesis.
Rifampicin
Each transcriptable region is called
Structural gene
*Is the DNA sequence that RNA-pol can bind.
*Is a region of DNA where transcription of a gene is initiated.
promoter
Repressor protein binding site
Operator
In a bacterial promoter, the TTGACG region is at __________ and the Pribnow region is at _________
-35 element
-10 element
Note: *Promoter + 1 is the transcription start site
Eukaryotic promoter
TATA box
Transcription of Prokaryotes:
*Initiation phase: RNA-pol recognizes the promoter and starts the transcription.
*Elongation phase: the RNA strand is continuously growing.
*Termination phase: the RNA-pol stops synthesis, and the nascent RNA is separated from the DNA template.