Gene Expression Flashcards
(29 cards)
3 Major Types of RNA in Eukaryotic Cells
rRNA
tRNA
mRNA
DNA Dependent RNA Polymerase
RNAPs are directed to specific genes which produce RNA from DNA
List the Ribonucleoside Triphosphates and discuss why they are different to the Nitrogenous bases
ATP - Adenylate
CTP - Cytidylate
GTP - Guanylate
UTP - Uridylate
These refer to the entire nucleotide with the base being specified
What to RNAPs to do RNA NTPs
They cause a polymerisation reaction whereby they join the NTPs together, releasing pyrophosphate which is taken up by other processes as it is high energy; it affects equilibrium
Transcription bubble in eukaryotes vs prokaryotes
Eukaryotic DNA is monocistronic while Prokaryotic DNA is polycistronic
Monocistronic means one gene per mRNA while polycistronic means the bubble can follow multiple genes at once with one big length of hnRNA; often has only one promoter
Operon
Unit of DNA with multiple genes
σ Factor
Like an adapter plug on RNAP that allows it to transcribe certain genes; the factors can be swapped out
Describe location of promoters in DNA
approx 35-40 bp upstream (5’ side) of Transcription Start Site (TSS)
Nomenclature of first nucleotide of transcription
+1; the last base before it is -1 (no 0 base)
Are promoters generally on the sense or antisense
Sense because idk
When promoters try to promote clubs, they try to have arguments that make sense (they never do but whatever)
Consensus sequences, example (just name) and how are they determined
Sequences that RNAPs like to bind to; are seen in different genes across organisms
Pribnow Box
RNAPs are bound to DNA, enzymes are thrown at the DNA to remove everything that isn’t protected by RNAPs and what remains is sequences
How does the Transcription bubble form
From the binding of RNAP leading to DNA ‘melting’ (Separating); bubble moves along the DNA along with the enzyme
What does it mean for RNAP to be processive
It does not dissociate from the template very often. It does about 180 rotations around DNA, with each being up to 1900bp long
What is one way that RNA is transcribed so quickly in prokaryotes
It is initiated at multiple different sites
How is DNA terminated in prokaryotes
Terminator sequence;
can often lead to RNA folding on itself to form a self-complimentary hairpin causing RNAP to pause and terminate due to a conformational change
Rho Factor
Helicase that winds and unwinds bits of DNA which binds to RNAP and tells it to stop (Seen when there is no terminator in some prokaryotic genes)
One way that eukaryotic transcription is more complex than prokaryotic
There are many different types of eukaryotic RNAPs (idk I just needed to put this information in here)
What is present in eukaryotes instead of a sigma factor
Accessory proteins
What causes different types of RNAPs to bind
Different promoters attract different RNAPs
Enhancer vs Silencer Proteins (In terms of transcription)
Proteins that encourage/prevent the occurrance of transcription
Can be upstream or downstream of the promoter
TF II
Transcription factor II, for RNAP 2
Equivalent of sigma factor; combines with enzyme and DNA to form pre-initiation complex
How can antibiotics affect transcription
They can act as inhibitors of prokaryotic RNAP by binding to RNAP and preventing elongation but not binding
- Rifamycin B
Actinomyocin D
Inhibits DNA replication and transcription by wedging itself in the helix and distorting it to prevent DNA dependent polymerases from binding
Used against cancers
Do prokaryotes and/or eukaryotes undergo post translational modification?
Only eukaryotes
