L01 Flashcards
Eukaryotic promoters, RNA polymerases & assembly of PIN complex
What is ‘gene expression’?
The process by which information in genes (DNA) is decoded into protein
Name the process DNA -> RNA
Transcription
Name the process RNA -> Protein
Translation
Define ‘transcription’
Transfer of genetic information from ds DNA to ss RNA (mRNA)
What is the purpose of DNA
Encode proteins
Role of gene expression
Determines the function of the cell/primary specifier of cell identity
How do cells respond to changes in the environment?
Gene expression is altered
What is the DNA sequence for -35 promoter in prokaryotes?
TTGACA
What is the DNA sequence for the -10 promoter in prokaryotes?
TATAAAT
How far is the TATA box from the TSS?
-31 ~ -26 (about 30 base pairs)
Why is it called the TATA box?
First 4 bases often, TATA
What is the pyrimidine rich sequence?
Inr (initiator)
Where is the initiator often located
-2 ~ +4
Does DNA have all the core (basal) promoter elements?
No
In mammals what percentage of protein coding genes lack obvious TATA & Inr?
60-70
How does methylation affect transcription in CpG islands?
Methylation of CpG islands = silencing txn
Non-methylation of CpG islands = promoting txn
What is methylation?
Addition of a methyl group
What residues are methylated in mammalian CpG islands?
Most C residues followed by a G (5-methyl C)