Stimulation of the sympathetic cardiac nerves speeds the depolarization in SA node.

TLS Online TPP Program

#Id: 5906

#Unit 3. Fundamental Processes

Each DNA helicase moves along ssDNA in a defined direction. This property is referred to as the polarity of the DNA helicase. DNA helicases can have a polarity of either 5’->3’ or 3’->5’.

TLS Online TPP Program

#Id: 5907

#Unit 3. Fundamental Processes

In the case of a DNA helicase that functions on the lagging-strand template of the replication fork, the polarity is 5’->3’ to allow the DNA helicase to proceed toward the duplex region of the replication fork The PhiX system, named originally for phage X174, requires an initiation complex consisting of additional components, called the primosome. This system is used when damage causes the replication fork to collapse and it must be restarted.

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