Exam Focus: Transfection methods are commonly asked as short notes (Microinjection, Lipofection, Electroporation). For selection, understand the principle and utility of the **HAT selection** medium, especially in Hybridoma technology.
Transfection is the introduction of **foreign nucleic acids (DNA or RNA)** into eukaryotic cells. The various methods aim to bypass the cell membrane barrier.
A physical method where a fine glass needle is used to **manually inject** the DNA or RNA directly into the cell nucleus or cytoplasm.
A chemical method using **liposomes** (lipid vesicles) or **lipofection** reagents (cationic lipids) that form complexes with the negatively charged nucleic acids. These complexes fuse with the cell membrane, mediating DNA entry.
A physical method using a brief, high-voltage electric pulse to create **transient pores** in the cell membrane, allowing the nucleic acid in the surrounding medium to enter the cell.
A physical method using **ultrasound waves** to temporarily disrupt the cell membrane structure, facilitating the uptake of nucleic acids from the surrounding medium.
| Method | Mechanism | Type |
|---|---|---|
| Microinjection | Direct physical delivery via needle. | Physical |
| Lipofection | Cationic lipid vesicles fuse with cell membrane. | Chemical |
| Electroporation | Electric pulse creates transient membrane pores. | Physical |
A specialized **selection technique** used in Hybridoma technology to isolate the desired hybridoma cells (fused B-cell × myeloma cell).
Genes encoded by the vector that confer a selective advantage (e.g., antibiotic resistance) to the host cell, allowing only successfully transfected cells to survive when grown under selective pressure.
Methods used to disrupt the function of an endogenous gene.