Question

What is the significance of selectable markers in cloning vectors?

Answer 1

Hint: The selectable markers are the gene substances that are injected in the cell so that it can offer resistance to the action of the antibiotics. This helps in the maintenance of the plasmid in the cell. Due to this selective marker, the plasmid serves very useful to the cell by making it survive.

Complete answer:
> They help to resist antibiotics since they have antibiotic resistant genes in them. Mainly the microorganisms like bacteria, fungi etc. are used for this purpose of selectable markers. They help in distinguishing transformants and specifically permitting their development while wiping out non-transformants in cloning vectors. These selectable markers help the traits in the artificial selection. Hence these selectable markers are used in the field of molecular biology, micro biology and genetic engineering.
> These markers are also called as the antibiotic resistance marker, when the cell expresses this protein, they get resistant against the antibiotics. The bacteria are subjected to introduce the foreign gene in it and it is grown to obtain the bacterial colonies. For example, antibiotics like ampicillin, tetracycline, kanamycin, chloramphenicol etc. are used for the selective marking for the E-coli. These selectable markers are classified into three types as positive, negative and the positive and negative selectable markers.

Note: The main disadvantages of using selectable markers are the selective pressure lost in the cell by causing the degradation of the antibiotics and it also inactivates it. The product to be used gets contaminated by the degraded antibiotics biomass in it, this makes the product unacceptable for the medical considerations.