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DNA Replication & Gene Expression Cheat Sheet (DRAFT) by

Module 3.1 - translation and transcription

This is a draft cheat sheet. It is a work in progress and is not finished yet.

DNA Replic­ation

-happens in SPhase
- proceeds bidire­ctional
-copying a DNA molecule
-semiconservative
-DNA unwinds and unzips 2 strands
- Daughter DNA
parent strand and newly synthesize
-unzip = superc­oiling

SUPERC­OILING

DNA Gyrase
-enzyme topoimerase
-creates a nick to relief torsional strain and release
Helicase
-Desta­bil­izing protein
-promotes unwinding by binding to RF
SSB
-stabilize single stranded regions

DNA POLYMERASE

-polym­eri­zation at 5' to 3'
|add in 3' end
-requires template to copy
|compl­eme­ntary strand
Types of dNTPs
dATP, dGTP, dCTP, dTTP
Primer
Organisms
RNA, DNA in some organisms
Viruses
Protein
DNTP - deoxyn­ucl­eotide tripho­sphate
adenine (dATP), cytosine (dCTP), guanine (dGTP), and thymine (dTTP)

DNA POLYMERASE

-polym­eri­zation at 5' to 3'
|add in 3' end
-requires template to copy
|compl­eme­ntary strand
Types of 4dNTPs
dATP, dGTP, dCTP, dTTP
Primer
Organism
RNA , but DNA in some organism
Virus
Protein
DNTP - deoxyn­ucl­eotide tripho­sphate
adenine (dATP), cytosine (dCTP), guanine (dGTP), and thymine (dTTP)
  

Models of DNA Replic­ation

SemiCo­nse­rvative
Conser­vative
Dispersive
-parent & new synthesis
-both original and new strands
-mosai­c/h­ybrid
-unwind each other
-rebase pair

Theta Replicaion

-present in bacteria (proka­ryotic)
- circular form

LAGGING AND LEADING STRAND

Lagging Strand
Leading Strand
-3' to 5'
-5' to 3'
-disco­nti­nuous
-conti­nuous
-okazaki fragments
-no short fragments
-each fragments requires its own set of primers
- requires only one primer
-requires DNA ligase
-no DNA ligase
-grows away from RF
-grows in direction of RF
-synthesis of new strands SLOW
-synthesis of new strands FAST
RF - Replic­ation Fork

REPLIC­ATION ORIGINS

-unique DNA segments
contains multimeric origin­binding protein
-ATrich stretch
less energy to melt A-T bp due to Hbonds

PROKAR­YOTIC DNA POLYMERASE

DNA polymerase I
-RNA primer removal, DNA repair
DNA polymerase II
-DNA repair
DNA polymerase III
-Chrom­osome replic­ation
 

MODELS OF DNA REPLIC­ATION

PROTEINS INVOLVED IN DNA REPLIC­ATION

Protein
Activity
DNA Polymerase
-initiates
-add nucleotide at 3' end
DNA Helicase
-unzip­/unwind DSDNA
-separates DNA strands
SSBS
-stabi­lizer
-preventing bp from reforming before lagging strand is replicated
DNA Topois­omerase
-reseal
-unravel twists in DNA
-reduce torsional strain & positive supercoil
Sliding Clamp
-keeps DNA polymerase attached to template
Clamp Loader
-lock sliding clamp to DNA (uses ATP hydrol­ysis)
Primase
-synthesis RNA primers in lagging strand
DNA Ligase
-seale­d/c­onnect okazaki
SSBS - Single Strand DNA Binding Protein
DSDNA- Double Strand DNA