Hoofdstuk 6 samenvatting (college+boek)(Molecular Biology of the Cell)

HC6

transcription -> RNA polymerase
- less precise
- no need for a primer
- no stable duplex formed
- speed comparable to DNA polymerase
- absolutely processive (aan 1 stuk door, zonder pauzes)
- many RNA copies can be made after each other
- completely unrelated in structure to DNA polymerases




promoter sequences are heterogeneous but contain common features that can be
expressed as a consensus sequence

RNA polymerase 1: ribosomaal RNA
RNA polymerase 2: alle protein-coding RNAs
RNA polymerase 3: tRNA en kleine RNAs

-> RNA polymerase in conserved in sequence and structure but eukaryotic enzymes are
more complex

, DNA gyrase in bacteria: introduction of negative supercoils facilitates unwinding
- ontvouwt DNA met behulp van ATP

prokaryotes: polycistronic unmodified mRNAs
eukaryotes: monocistronic, capped and polyadenylated mRNAs

mRNA in prokaryotes can end up as several proteins
mRNA in eukaryotes is always just one protein




specificity of mRNA splicing is because of snRNP
- snRNP is a protein/RNA complex that binds at the
splicing sites and facilitates the splicing process
- the U proteins all bind to a portion of the mRNA and
come together to let the splicing happening

splicing consensus sequence recognition requires base
pairing with snRNP RNAs
- splice site is read by two snRNPs: good for
accuracy but requires additional energy
- snRNP rearrangements create catalytic sites for
splicing reaction -> orderly progression
- catalytic sites consist of RNA and proteins