NEET BIOLOGY

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GENETICS AND EVOLUTION

MOLECULAR BASIS OF INHERITANCE

Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
You briefly expose bacteria undergoing DNA replication to radioactively labeled nucleotides. When you centrifuge the DNA isolated from the bacteria, the DNA separates into two classes. One class of labeled DNA includes very large molecules (thousands or even millions of nucleotides long), and the other includes short stretches of DNA (several hundred to a few thousand nucleotides in length). These two classes of DNA probably represent
A
leading strands and RNA primers.
B
Okazaki fragments and RNA primers.
C
lagging strands and Okazaki fragments.
D
leading strands and Okazaki fragments.
Explanation: 

Detailed explanation-1: -DNA is isolated from bacteria undergoing DNA replication. After heat treatment to disrupt H-bonds the DNA is centrifuged and it separates into two classes. One class of DNA includes very large molecules, and the other includes short stretches of DNA.

Detailed explanation-2: -Helicases are enzymes that bind and may even remodel nucleic acid or nucleic acid protein complexes. There are DNA and RNA helicases. DNA helicases are essential during DNA replication because they separate double-stranded DNA into single strands allowing each strand to be copied.

Detailed explanation-3: -The similarities between prokaryotic and eukaryotic replication can be understood as follows: Both the replication processes occur before nuclear division. The DNA involved in both processes are double-stranded. The replication occurs in 5’ to 3’ direction.

Detailed explanation-4: -What would happen if a cell replicates once in the presence of this radioactive bacteria? DNA in both daughter cells would be radioactive.

There is 1 question to complete.
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