12th Class Biology Sample Paper Biology - Sample Paper-8

State the cause behind the discontinuous synthesis of DNA on one parental strand and what happens to the short stretches of DNA that are synthesised during this process.

Answer:

DNA polymerase can polymerise nucleotides only in 5?\[\to \]3? direction on 3'\[\to \]5' strand because it adds them at the 3' end. Since, the two strands of DNA run in antiparallel directions, the two templates provide different ends for replication. One strand with polarity 3'\[\to \]5' forms its complementary strand continuously because 3' end of the latter is always open for elongation.

Replication is discontinuous on the other template with polarity 5'\[\to \]3' because only a short segment of DNA strand can be built in 5'\[\to \]3' direction due to exposure of a small stretch of template at one time. Short segments of replicated DNA are called Okazaki fragments. These Okazaki fragments are joined together by means of enzyme, DNA ligase.

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12th Class Biology Sample Paper Biology - Sample Paper-8

question_answer State the cause behind the discontinuous synthesis of DNA on one parental strand and what happens to the short stretches of DNA that are synthesised during this process.

State the cause behind the discontinuous synthesis of DNA on one parental strand and what happens to the short stretches of DNA that are synthesised during this process.