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Final

BIOL 200 Study Guide - Final Guide: Barcode, Histone H2A, Retrotransposon


Department
Biology (Sci)
Course Code
BIOL 200
Professor
Mathieu Roy
Study Guide
Final

Page:
of 10
PROKARYOTIC TRANSCRIPTION (DNA -> MRNA)
DNA template
o serve as a blueprint for the RN sequence
ribonucleotides
serve as monomers for RNA polymerixation
rna polymerase
o DNA dependant RNA polymerase
catalyze the synthesis of RNA
INITIATION
1. RNA polymerase binds to the promoter region
a. AT rich => facilitates the melting of the two strands
2. polymerase melts duplex dna near the transcription start site
a. transcription bubble/open complex
3. polymerase catalyzes the phosphodiester linkage of two initial rNTP's
TRNASCRIPTION
prokayrotes
o compact, circular genomes
o genes of similar function are grouped together
o no nucleus (genome sits in the periplasm)
transcribe the entire RNA
o trp mRNA: start sites for protein synthesis (POLYCISTRONIC mRNA)
rarely happens in eukaryotes
no modular format
all on the same promoter
o eukaryotes: different promoters
operons -
EUKARYOTIC TRANSCRIPTION
results in multiple mRNA's: specific for each protein
theoretically one ribosome to transcribe each mRNA
POST-TRANSCRIPTIONAL MODIFICATION
addition of the 5' cap
addition of the 3' poly-A tail
splicing
DNA REPLICATION
semi-conservatice
performed by DNA polymerase
o DNA dependent DNA polymerase
requires dNTP's
requires a primer (DNA or RNA)
proceeds in a 5' -> 3' direction
PROKARYOTIC REPLICATION
TOPOISOMERASE: relieves supercoils
o found in prokaryotes & eukaryotes
o binds upstream to the replication fork (far enough away to do it's job)
HELICASE: unwinds duplex DNA
o rate limiting step in DNA replication
LEADING STRAND SYNTHESIS
o primer catalyzed by
o DNA dependent DNA polymerase
LAGGING STRAND SYNTHESIS
o -dna Is elongated from an RNA primer (formed by primase) by DNA polymerase
o OKAZAKI FRAGMENTS: hybrid of DNA & RNA
get rid of RNA component with RNAsH
two adjoining molecules are ligated together by DNA ligase
ENDONUCLEASE: anything that cuts in the middle
EUKARYOTIC DNA POLYMERIZATION
SV40 as a model of eukaryotic DNA replication
LARGE T-ANTIGEN
o 6 subunits which are identical to eachother
o helicase: very fast
able to replicate DNA much faster
o encoded by the viral genome
as the large t-antigen
REPLICATION PROTEIN A (RPA)
o binds single stranded DNA
o keeps DNA in optimal conformation for copying by DNA polymerase
o PROTEIN: single stranded binding protein (SSbP)
DNA POLYMERASE DELTA (POL DELTA)
o proofreading activity
replication factor C
proliferating cell nuclear antigen (PCNA)
o carry out leading strand DNA syntehsis
o RPA is displaced as sysnthesis proceeds
primase/pol-alpha complex
o primase formats the RNA componenet of the primer and DNA polymerase....
o on leading + lagging strand
pol delta/ rfc / PCNA complex
prokaryotes - only have primase
eukaryotes - have primase + pol delta
DNA POLYMERASE ALPHA - make a dna primer for the okazaki fragment
o only occurs in eukaryotes
RIBNUCLEASE H & FEN-1
displace the RNA componenet at the 5' ends of the okazaki fragments
after ribonuclease H & FEN 1
polymerase delta replaces RNA with DNA
DNA fragments are then ligated together by DNA ligase
EXONUCLEASES AND ENDONUCLEASE
EXONUCLEASES - liberate single nucleotides at either end
ENDONUCLEASES - cleaves phosphodiester bonds with a polynucleotide …
o sticky or blunt ends
SOME DNA POLYMERASES HAVE A PROOFREADING ACTIVY
motifs which have different functions
polymerase: adds n.t. to the growing DNA polymer
polymerase delta (not alpha)