Pseudogenes arise from the action of an enzyme called reverse transcriptase

TLS Online TPP Program

#Id: 5917

#Unit 3. Fundamental Processes

The holoenzyme is a complex of 900 kD that contains 10 different proteins organized into four types of subcomplex

1. Atleast two copies of the catalytic core.

2. two copies of the dimerizing subunit, t, which link the two catalytic cores together.

3. There are two copies of the clamp

4. The g complex is a group of seven proteins, encoded by five genes, that comprise the clamp loader

TLS Online TPP Program

#Id: 5918

#Unit 3. Fundamental Processes

The holoenzyme assembles on replication fork DNA in three stages:

1. First the clamp loader uses hydrolysis of ATP to bind b subunits to a template primer complex.

2. Binding to DNA changes the conformation of the site on b that binds to the clamp loader, and as a result it now has a high affinity for the core polymerase

3. A t dimer binds to the core polymerase, and provides a dimerization function that binds a second core polymerase

TLS Online TPP Program

#Id: 5919

#Unit 3. Fundamental Processes

This is equivalent to nick translation, except that the new DNA replaces a stretch of RNA rather than a segment of DNA.

TLS Online TPP Program

#Id: 5920

#Unit 3. Fundamental Processes

Trombone” model for coordinating replication by two DNA polymerases at the E. coli replication fork

TLS Online TPP Program

#Id: 5921

#Unit 3. Fundamental Processes

Each Okazaki fragment starts with a primer and stops before the next fragment

TLS Online TPP Program

#Id: 5922

#Unit 3. Fundamental Processes

The 5’–3’ exonuclease activity removes the RNA primer while simultaneously replacing it with a DNA sequence extended from the 3’–OH end of the next Okazaki fragment.