The most useful range for proteins is above 230 nm, where there are absorptions from aromatic side chains While a very weak absorption maximum of phenylalanine occurs at 257 nm, tyrosineand tryptophan dominate the typical protein spectrum with their absorption maxima at 274 nm and 280 nm, respectively

#Id: 3159

#Unit 3. Fundamental Processes

 Eukaryotic cells have many DNA polymerases. The replication enzymes operate with high fidelity. Except  for the β enzyme, the repair enzymes all have low fidelity.

#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.