Michael Sheetz The Cell as A Machine page 18
Taking the complex function of DNA replication as an example, the formation of two identical double strands from one takes many steps. At a basic level, the existing double-stranded DNA must first be separated into the two strands that have opposite polarities by helicases. One DNA polymerase can move with the helicases to assemble a complementary strand of one of the original strands, called the forward strand. However, another DNA polymerase must move in the opposite direction on the other original strand (lagging strand) because of chemical constraints. In a roughly periodic fashion, a new DNA polymerase will assemble on the emerging lagging strand and assemble the complementary strand until it encounters the end of the previous complementary strand. Then the polymerase will disassemble and the two ends of the new complementary strand will be joined in a separate step. In this brief description of the process, many details were left out that were involved in proofreading and repairing errors, joining these segments with others, etc. All of these steps are highly orchestrated and must all occur before the cell can proceed in the cell cycle. It is, indeed, similar to an automobile assembly line with different tasks being performed by separate workers (functional modules) in a coordinated fashion and with inspections/repairs by other workers before the final product can be accepted. At this point of our understanding, it is not necessarily clear how the coordination of functional modules actually occurs in many contexts (whether through force, position or timing), but there is a lot of engineering needed to create the robust emergent properties of the system.
https://3lib.net/book/5508643/480307
Taking the complex function of DNA replication as an example, the formation of two identical double strands from one takes many steps. At a basic level, the existing double-stranded DNA must first be separated into the two strands that have opposite polarities by helicases. One DNA polymerase can move with the helicases to assemble a complementary strand of one of the original strands, called the forward strand. However, another DNA polymerase must move in the opposite direction on the other original strand (lagging strand) because of chemical constraints. In a roughly periodic fashion, a new DNA polymerase will assemble on the emerging lagging strand and assemble the complementary strand until it encounters the end of the previous complementary strand. Then the polymerase will disassemble and the two ends of the new complementary strand will be joined in a separate step. In this brief description of the process, many details were left out that were involved in proofreading and repairing errors, joining these segments with others, etc. All of these steps are highly orchestrated and must all occur before the cell can proceed in the cell cycle. It is, indeed, similar to an automobile assembly line with different tasks being performed by separate workers (functional modules) in a coordinated fashion and with inspections/repairs by other workers before the final product can be accepted. At this point of our understanding, it is not necessarily clear how the coordination of functional modules actually occurs in many contexts (whether through force, position or timing), but there is a lot of engineering needed to create the robust emergent properties of the system.
https://3lib.net/book/5508643/480307
