PASSAGE
Read the sentence and answer the questions.
The process of replication requires a set of catalyst (enzymes). The main enzyme is referred to as DNA dependent DNA Polymerase. E. coli that has only 4.6 × 106 bp (compare it with human whose diploid content is 6.6 × 106 bp), completes the process of replication within 18 minutes, that means the average rate of polymerisation has to be approximately 2000 bp per second these polymerase also have catalyse the reaction with high degree of accuracy. Deoxyribonucleoside triphosphates serve dual purposes. In addition to DNA dependent DNA polymerases, many additional enzymes are required to complete the process of replication with high degree of accuracy. For long DNA molecules, since the two strands of DNA cannot be separated in its entire length (due to very high energy requirement), the replication occur with in a small opening of the DNA helix, referred to as replication fork. The DNA-dependent DNA polymerase catalyse polymerisation only in one direction, that is 5′→3′. This creates some additional complications at the replicating fork. Consequently, on one strand (the template with polarity 3′→5′) the replication is continuous, which on the others (the template with polarity 5′→3′), it is the discontinuous. The non-continuously synthesized fragments are later joined by the enzyme DNA ligase.
In E. coli DNA polymerase complete the process of replication in __________
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → 18 Minutes
DNA replication is the copying of the whole DNA of a cell before it divides. The main enzyme is DNA-dependent DNA polymerase, which uses a DNA strand as the template to build a new strand.
The passage says that E. coli, which has only 4.6 × 106 bp, completes replication within 18 minutes. For this, the polymerase must add about 2000 bp every second. So these polymerases are very fast, and they must also be very accurate, because a mistake in copying is a mutation.
Note: The passage is taken from NCERT. NTA has put lines of the NCERT text together to make it. Most CUET (UG) questions come straight from NCERT, so study the book line by line, including figures and their titles.