Question

Is ori a selectable marker?

Answer 1

DNA replication:

1. The mechanism through which a double-stranded DNA molecule is copied to provide two identical DNA molecules is known as DNA replication.
2. The DNA is copied through enzymes known as DNA polymerases which act on single-stranded DNA synthesizing a brand new strand complementary to the original strand.
3. DNA synthesis constantly takes place withinside the path 5' →3'.
4. The replication fork is in which the helix unwinds and new DNA is synthesized. The following are the stages of DNA replication.
5. Unwinding: The old strands that make up the parent DNA molecule are unwound and “unzipped” through the motion of a unique enzyme known as helicase.
6. Leading and lagging strand: Synthesis of DNA through DNA polymerase takes place most effectively withinside the 5' → 3' path.
7. The strands of the double helix of DNA run in the opposite direction to each other.
8. The strand that is replicated in the same direction as the unwinding helix and so can be synthesized constantly is known as the main strand.
9. The other strand known as the lagging strand is synthesized in the opposite direction and must be copied discontinuously resulting in “Okazaki fragments”.
10. Priming: DNA polymerase enzymes require a short double-stranded region to initiate or prime DNA synthesis, which is produced by an RNA polymerase, called primase, which is able to initiate the synthesis of one single-stranded DNA.
11. Joining: The very last step required to finish the synthesis of the lagging strand is for the Okazaki fragments to be joined together by phosphodiester bonds which are carried out by a DNA ligase.
12. Ori means the origin of replication, hence it is not a selectable marker.
13. Selectable markers are genes that integrate into cells, especially when bacteria or cells are present in culture, and confer properties suitable for artificial selection.
14. An origin of replication or an origin of replication is a specific sequence in the genome where replication is initiated.