Module 2 Initiation + Elongation
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DNA replication is a sequence of repeated ____ ( _____) reactions linking nucleotide monomers into a DNA polymer. DNA replication has 3 parts:
Condensation (dehydration synthesis) Initiatioin Elongation Termination
INITIATION: DNA synthesis starts at one or more ____ which are DNA sequences targeted by ____ These are usually rich in ____ and ____ bases because the TWO Hydrogen bonds they have together require less energy
Origins of replication Initiator Proteins Adenine Thymine
INITIATION: _______ Region of DNA served by one replication origin ____ control the initiation of DNA replication by directing assembly of the replication machinery Three common features of Replication Origins 1 Unique DNA segments that contain multiple _____ sequences 2 These sequences are recognized by _____ 3 Origin regions usually contain an ____
Replicon Origin-binding proteins 1) Short Repeated Sequences 2) Multimericorigin-bindding proteins 3) AT-rich stretch
INITIATION: Three types of replication origins:
E. coli oriC yeast autonomously replicating sequences (ARS) simian virus (SV40) Origin
______ DNA nucleotides are then added to the ____ of primers by a _____.
Elongation 3’ end DNA polymerase
What allows the lagging strand to make fragments? The creation of a ____ allowing the enzyme to add nucleotides at a 3-hydroxyl end of a growing segment. These create okazaki fragments. There are about ____ to ___ nucleotides in a fragment in e coli but ____ to ____ in eukaryotes. Synthesis occur at the same rate DNA polymerase can’t start a new chain as they need a ____ RNA Polymerase can start a new chain.
Trombone structure 1000 to 2000 e coli 100-200 eukaroytes polynucleotide primer
_____ The enzyme that is responsible for the polymerization of nucleotides to nucleic acid (DNA) during the elongation phase The first was discovered in E. coli by ____ for which he received the ____. It was specifically the ____ kind. It was _____, the son who found out two more DNA polymerase
DNA polymerase Arthur Kornberg 1959 Nobel Prize in Chemistry DNA Pol I Thomas Kornberg
E. Coli DNA Pol I has 3 enzymatic activities 5’ -> 3’ 3’ -> 5’ 5’ -> 3’
5’ -> 3’ Polymerization 3’ -> 5’ Exonuclease Proofreading 5’ -> 3’ Exonuclease, edit sections of damaged DNA
DNA Pol III is highly ____ DNA Pol I is ____ ______ continuous synthesis without dissociation from template, leading strand ______ dissociate from the template after each nucleotide addition, lagging strand
DNA Pol III Processive DNA Pol I Distributive Processive Distributive
DNA Polymerase I DNA Polymerase II DNA Polymerase III DNA POlymerase IV DNA Polymerase V
Removes primers DNA repair, restarts replication, halts synthesis Elongates DNA DNA Repair DNA Repair, translesion DNA synthesis
Mammalian cells: _____ Initiation of nuclear DNA synthesis and DNA repair, primase activity _____ DNA repair and reccombination of nuclear DNA _____ Replication and repair of mitochondrial DNA ______ Leading and lagging strand synthesis of nuclear DNA ______ Solely Leading strand synthesis
a B+ y o E
Detection of replication errors and corrections (3):
Extension error Proofreading -hydrolysis of nucleotide Extension