Answer:
The donor insert contains the antibiotic resistance gene's encoding. On the basis of this, they are already chosen for the trial.
Step-by-step explanation:
Bacterial cells can develop antibiotic resistance in two different ways. One way is by way of mutations that take place in the cell's DNA during replication. Through horizontal gene transfer, bacteria can also develop resistance.
How does DNA Replication work?
The first step in DNA replication is to ‘unzip’ the double helix structure of the DNA molecule. Helicase breaks the hydrogen bonds holding the complementary bases of DNA together (A with T, C with G). The separation of the two single strands of DNA creates a ‘Y’ shape called a replication ‘fork’. The two separated strands will act as templates for making the new strands of DNA. One oriented in the 3’ to 5’ direction, is the leading strand. The other oriented in the 5’ to 3’ direction is the lagging strand.
DNA polymerase binds to the leading strand and then ‘walks’ along it, adding new complementary nucleotide bases (A, C, G and T) to the strand of DNA in the 5’ to 3’ direction. Once all of the bases are matched up (A with T, C with G), an enzyme called exonuclease strips away the primer(s). The gaps where the primer(s) were are then filled by yet more complementary nucleotides. The new strand is proofread to make sure there are no mistakes in the new DNA sequence.
Finally, an enzyme called DNA ligase seals up the sequence of DNA into two continuous double strands.
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