transcription

telermerase

adds repeating codes to lagging strand because of the gaps.

flap endonuclease

cuts the flap( RNA primer) and ligase goes in and seals it

RNa poly assembles nucleotides on?

template strand, no primer needed, reads 3’ to 5’, but adds 5’ to 3’. ( adds to 3’ end)

Sigma( initiation)(pro)

part of RNa poly, binds to promotor sequenses. It positions the rna poly on the DNA template. It dissociates from core enzyme after transcription starts.

elongation(pro)

polycistronic, one mrna contain sequence from serveral genes, can encode serveral proteins

termination(pro)

2 mechanisms that can occur intrinsic and Rho-dependent

Intrinsic termination(pro)

hairpin strucutre in rna causes RNA polymerase to stall, rna-duplex dissociates due to weak dissociation between rna and dna

rho-dependent termination ( pro)

causes poly to stall, (rho) helicase unwinds the RNa-DNA duplex

prokaryote

1 type of rna poly, transcription and translation near each other, polycistroni mrna( several protein sencoded in one mrna), limited rna processing

eukaryotes

3 different types of rna poly, transcription and translation spatially seperate, monocistronoc mrna( one protein encoded in one mrna), mrna is processed( capped, polydenylated, spliced) before exported from nucleus.

initiation (euk))

transcription factors bind to core promotor andn recruit RNA poly to form PIC

elongation (euk)

adds to 3’, 5’ m7g cap is added to mRNa, introns are spliced out ( exons are spliced together) to form a continuous codingn sequence

m7g cap

added to the 5’ end of the mRNA , it attaches by a 5’5 linkage when mRNa is 20-30 nucleotides long, needed for translation, protects RNA from 5’ to 3’ exonucleases

introns

removal of introns= splicing, noncoding sequcnes called introns. They are transcribed but not translated

splicing

spliceosome is made of subunits of RNA and protein. Subunits called snRNP( small noclear ribosnucleo protein), has 5’ splice, 3’ splice and branch point A, loop out introns

termination(euk)

mrna is cleaved at the polya cleavage site, mrna is relased from transcription bubble, and polyadenylated. about 250 atp are added to 3’ of rna by poly a polymerase, poly a tail coated with protein, needed for translation, protects 3’ end of mrna from 3’ exonucleases

RNA poly in euk

poly 1- rna poly( nucleolus) 2: mrna( nucleoplasm) and snrna, ppoly 3: tRNA( nucleoplasm)

mRNa

exact copy of the coding(sense) strand except Thymines are Uracils. mRNA is complemtary to template( antisense). if mrna is 5’ to 3’, template is 3’ 5’, so flip it if it asks for 5’ to 3’

translation:

makes a polypeptide- polymers if amino acids connected by peptide bond. Read 5’ 3’ . genetic code is umambigious, one codon specifies for one amino acid.

trna

becomes charged when high energy acyl bond connect to its matching amino. uncharged=tRNA phe, charged= phe-tRNAhe, charging is also alled aminoacylation, and it is catalyzed by tRNA synthetase. 165rRNA is used to identify.

translation (prok)

has ribosome binding sequence, happens contranscriptionally, linear translation

translation (euk)

start codon near kozak, happens only after processing and transport from nucleus is complete, closed loop translation.