Ch 14&16: Transcription and Translation Flashcards
genome
entire collection of all DNA of an organism
transcription
process where RNAP II copies one of the two strands of DNA to make RNA
mRNA
messenger RNA
encodes a sequence that a ribosome can copy (translation) to make a protein
only class of RNA that is translated by ribosomes into a protein
rRNA
makes ribosomes
tRNA
transfer RNA
used during RNA
snRNA
small nuclear RNA
helps with RNA processing (splicing)
siRNA
small interfering RNA
helps regulate protein levels
ncRNA
noncoding RNA
helps regulate gene expression
Gene expression
the name given to the entire process leading from transcription to translation
regulation of gene expression
the control of the processes of transcription and translation
Kinds of RNAps
most bacteria have one RNAP
eukaryotes have 3 RNAPs, RNAP I (rRNA), RNAP II (mRNA and snRNA), RNAP III (tRNA)
RNAP II is the one used for transcription and translation
Does RNAP require a primer?
NO
can synthesize an entire RNA without falling off (processive)
In what direction does RNA synthesis proceed in?
5’-3’
template strand or transcribed strand
DNA strand being copied by RNAP
non-transcribed strand
strand not being copied
RNAP structure
Eukaryotic RNAPs have 12 subunits or peptides (Rpb 1-12)
bacterial RNAPs have five subunints or peptides, alpha, beta, beta prime, etc
initiation
RNAP finds the place to start transcription with the help of TxF’s
aka Tss and the first template base is +1
elongation
RNAP leaves the start site and synthesizes RNA
Termination
RNAP is stopped and RNAP is released from the DNA
where does initiation occur in bacteria
sigma subunit recognizes two specific sequences in DNA that are located at -10 sequence and -35 sequence
In order for RNA synthesis to being, the non-transcribed DNA must be separated from the transcribed strand which is also done by sigma
sigma dissociated from RNAP in the elongation phase
where does initiation occur in eukaryotes
none of the 12 subunits of eukaryotic RNAP recognize a specific DNA sequence
auxiliary transcription factors (GTFs) bind to specific sequences near the vicinity of the TSS and assist RNAP to find where to start RNA synthesis
