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TLS Online TPP Program

#Id: 4052

Each is produced by the successive replications of a synapsed diploid pair of chromosomes. The replicas do not separate, but instead remain attached to each other in their extended state, a process known as endoreduplication.
At the start of the process, each synapsed pair has a DNA content of 2C (where C represents the DNA content of the individual chromosome). This amount then doubles up to nine times, at its maximum giving a content of 1024C. The number of doublings is different in the various tissues of the D. melanogaster larva.

#Unit 2. Cellular Organization #CELL CYCLE #Part B Pointers
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TLS Online TPP Program

#Id: 5902

#Unit 3. Fundamental Processes

The lagging strand must be synthesized in the form of Okazaki fragments of 1000 bp -2000 bp
TLS Online TPP Program

#Id: 5903

#Unit 3. Fundamental Processes

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. Thus, the lagging strand is synthesized discontinuously and the leading strand is synthesized continuously. This is called semidiscontinuous replication.
TLS Online TPP Program

#Id: 5904

#Unit 3. Fundamental Processes

A new model for the structure of the DNA Pol III complex proposes a three-polymerase core structure, with two Pol III catalytic cores responsible for synthesis of the lagging strand and one for the leading strand.
TLS Online TPP Program

#Id: 5905

#Unit 3. Fundamental Processes

Enzymes responsible for PTJ Helicase is hexameric and motor that melts the duplex and requires ATP hydrolysis—typically 1 ATP is hydrolyzed for each base pair that is unwound.
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.