Nonselective cation channels open in response to binding of the second messenger cGMP (cGMP-gated channels)

TLS Online TPP Program

#Id: 3008

#Unit 3. Fundamental Processes

That not all of the fragment population represents bona fide Okazaki fragments; some are pseudo fragments that have been generated by breakage in a DNA strand that actually was synthesized as a continuous chain. The source of this breakage is the incorporation of some uracil into DNA in place of thymine. When the uracil is removed by a repair system, the leading strand has breaks until a thymine is inserted. 

TLS Online TPP Program

#Id: 3009

#Unit 3. Fundamental Processes

Replication requires a helicase to separate the strands of DNA using energy provided by hydrolysis of ATP.

TLS Online TPP Program

#Id: 3010

#Unit 3. Fundamental Processes

A single-stranded DNA-binding protein is required to maintain the separated strands.

TLS Online TPP Program

#Id: 3011

#Unit 3. Fundamental Processes

The E. coli SSB is a tetramer; eukaryotic SSB (also known as RPA) is a trimer.

TLS Online TPP Program

#Id: 3012

#Unit 3. Fundamental Processes

A helicase usually initiates unwinding at a single-stranded region adjacent to a duplex. Note that it cannot unwind a segment of duplex DNA; it can only continue to unwind a sequence that has been started.

TLS Online TPP Program

#Id: 3013

#Unit 3. Fundamental Processes

Helicase, It may function with a particular polarity, preferring single-stranded DNA with a 3 ' end (3'-5' helicase) or with a 5' end ( 5 '-3' helicase).