Gene7-13

13.3 DNA polymerases have various nuclease activities
Figure 13.5 Nick translation replaces part of a pre-existing strand of duplex DNA with newly synthesized material.
13.5 Some DNA polymerases have a common structure
Figure 13.8 The catalytic domain of a DNA polymerase has a DNA-binding cleft created by three subdomains. The active site is in the palm. Proofreading is provided by a separate active site in an exonuclease domain.
13.6 DNA synthesis is semidiscontinuous
Lagging strand of DNA must grow overall in the 3′-5′ direction and is synthesized discontinuously in the form of short fragments (5′-3′) that are later connected covalently. Leading strand of DNA is synthesized continuously in the 5′3′ direction. Okazaki fragments are the short stretches of 1000-2000 bases produced during discontinuous replication; they are later joined into a covalently intact strand. Semidiscontinuous replication is mode in which one new strand is synthesized continuously while the other is synthesized discontinuously.
13.2 DNA polymerases are the enzymes that make DNA
Figure 13.1 Semiconservative replication synthesizes two new strands of DNA.
13.2 DNA polymerases are the enzymes that make DNA
Figure 13.12 There are several methods for providing the free 3OH end that DNA polymerases require to initiate DNA synthesis.
13.5 Some DNA polymerases have a common structure
13.2 DNA polymerases are the enzymes that make DNA
Figure 13.4 Only one DNA polymerase is the replicase. The others participate in repair of damaged DNA.
13.7 Single-stranded DNA is needed for replication
SSB is the single-strand protein of E. coli, a protein that binds to single-stranded DNA.
13.10 Coordinating synthesis of the lagging and leading strands
13.4 DNA polymerases control the fidelity of replication
Figure 13.6 Bacterial DNA polymerases scrutinize the base pair at the end of the growing chain and excise the nucleotide added in the case of a misfit.
13.1 Introduction
Replisome is the multiprotein structure that assembles at the bacterial replicating fork to undertake synthesis of DNA. Contains DNA polymerase and other enzymes.
Figure 13.7 Crystal structure of phage T7 DNA polymerase has a right hand structure. DNA lies across the palm and is held by the fingers and thumb. Photograph kindly provided by Charles Richardson and Tom Ellenberger.
13.2 DNA polymerases are the enzymes that make DNA
DNA polymerases are enzymes that synthesize a daughter strand(s) of DNA (under direction from a DNA template). May be involved in repair or replication. DNA replicase is a DNA-synthesizing enzyme required specifically for replication. Repair of damaged DNA can take place by repair synthesis, when a strand that has been damaged is excised and replaced by the synthesis of a new stretch. It can also take place by recombination reactions, when the duplex region containing the damaged is replaced by an undamaged region from another copy of the genome. Replication of duplex DNA takes place by synthesis of two new strands that are complementary to the parental strands. The parental duplex is replaced by two identical daughter duplexes, each of which has one parental strand and one newly synthesized strand. It is called semiconservative because the conserved units are the single strands of the parental duplex.
13.3 DNA polymerases have various nuclease activities
13.3 DNA polymerases have various nuclease activities
13.8 Priming is required to start DNA synthesis
Figure 13.2 Repair synthesis replaces a damaged strand of DNA.
13.2 DNA polymerases are the enzymes that make DNA
Figure 13.3 DNA synthesis occurs by adding nucleotides to the 3-OH end of the growing chain, so that the new chain is synthesized in the 5-3 direction. The precursor for DNA synthesis is a nucleoside triphosphate, which loses the terminal two phosphate groups in the reaction.
13.4 DNA polymerases control the fidelity of replication
Proofreading refers to any mechanism for correcting errors in protein or nucleic acid synthesis that involves scrutiny of individual units after they have been added to the chain.
Chapter 13
DБайду номын сангаасA replication
13.1 Introduction 13.2 DNA polymerases are the enzymes that make DNA 13.3 DNA synthesis is semidiscontinuous 13.4 Coordinating synthesis of the lagging and leading strands 13.5 The replication apparatus of phage T4 13.6 Creating the replication forks at an origin 13.7 Common events in priming replication at the origin 13.8 Does methylation at the origin regulate initiation? 13.9 Licensing factor controls eukaryotic rereplication
13.3 DNA polymerases have various nuclease activities
Nick translation describes the ability of E. coli DNA polymerase I to use a nick as a starting point from which one strand of a duplex DNA can be degraded and replaced by resynthesis of new material; is used to introduce radioactively labeled nucleotides into DNA in vitro.
13.6 DNA synthesis is semidiscontinuous
Figure 13.9 The leading strand is synthesized continuously while the lagging strand is synthesized discontinuously.