The prospective lens cells secrete paracrine factors that instruct the optic vesicle to form the retina. 

TLS Online TPP Program

#Id: 5908

#Unit 3. Fundamental Processes

E. coli SSB is a tetramer of 74 kD that binds single-stranded DNA cooperatively

TLS Online TPP Program

#Id: 5909

#Unit 3. Fundamental Processes

A common feature of all DNA polymerases is that they cannot initiate synthesis of a chain of DNA de novo, but can only elongate a chain.

TLS Online TPP Program

#Id: 5910

#Unit 3. Fundamental Processes

The 3’–OH end is called a primer.

A sequence of RNA is synthesized on the template, so that the free 3’–OH end of the RNA chain is extended by DNA Pol and This is commonly used in replication of cellular DNA and by some viruses.

In case of reteroviruses, A preformed RNA (often a tRNA) pairs with the template, allowing its 3’–OH end to be used to prime DNA synthesis.

TLS Online TPP Program

#Id: 5911

#Unit 3. Fundamental Processes

Each Okazaki fragment starts with a primer sequence of RNA 10 bases long that provides the 3’–OH end for extension by DNA polymerase

TLS Online TPP Program

#Id: 5912

#Unit 3. Fundamental Processes

The DnaG primase is an RNA polymerase is smaller than RNA Polymerase; and synthesizes short stretches of RNA that are used as primers for DNA synthesis.

TLS Online TPP Program

#Id: 5913

#Unit 3. Fundamental Processes

DnaG primase associates transiently with the replication complex, and typically synthesizes a 10-base primer. Primers start with the sequence pppAG positioned opposite the sequence 3’–GTC-5’ in the template.