In higher plants the phytochrome chromophore is a linear tetrapyrrole called phytochromobilin

#Id: 3160

#Unit 3. Fundamental Processes

Replication enzymes have large structures, with separate subunits for different activities. Repair enzymes have much simpler structures.

#Id: 3161

#Unit 3. Fundamental Processes

The conserved function of the replication components extends to the clamp loader and processivity clamp as well other functions of the replisome.

The roles of RFC and PCNA are analogous to the E. coli γ clamp loader and β2 processivity unit

#Id: 3168

#Unit 3. Fundamental Processes

Three different DNA polymerases make up the eukaryotic replication fork

Pol α/rimase is responsible for primer synthesis on the lagging strand.

The MCM helicase (the eukaryotic homolog of Dna B ) unwinds the dsDNA, while 

PCNA (homolog of ex) endows the complex with processivity.

#Id: 3169

#Unit 3. Fundamental Processes

#Id: 3170

#Unit 3. Fundamental Processes

The ter site is recognized by a unidirectional contrahelicase (called Tus in E. coli and RTP in B. subtilis) that recognizes the consensus sequence and prevents the replication fork from proceeding.

#Id: 3171

#Unit 3. Fundamental Processes

The E. coli enzyme acts by antagonizing the replication helicase in a direction a) manner by direct contact between the DnaB helicase and Tus.