transformation
Summary
Transformation refers to the process by which bacteria take up free extracellular DNA from their environment, incorporating it into their genome. In molecular biology and oncology, the term also describes the conversion of normal cells into malignant cells (neoplastic transformation) via genetic/epigenetic alterations, often driven by oncogenic viruses or mutations.
Detail
In microbiology, transformation is one of three mechanisms of horizontal gene transfer in bacteria (alongside conjugation and transduction). Naturally competent bacteria (e.g., Streptococcus pneumoniae, Neisseria, Haemophilus influenzae, Bacillus subtilis - mnemonic 'SHiN') can uptake naked DNA from lysed bacteria in their environment. This DNA integrates into the recipient genome via homologous recombination, potentially conferring new traits such as antibiotic resistance or virulence factors (e.g., capsule genes). This process is exploited in molecular biology techniques (e.g., transforming E. coli with plasmids using heat shock or electroporation) for recombinant DNA technology, cloning, and genetic engineering—foundational to biotechnology and vaccine/antibody production.
In oncology/cell biology, 'transformation' describes the process by which normal cells acquire a malignant phenotype—characterized by loss of contact inhibition, uncontrolled proliferation, immortalization, and invasive potential. This can occur through oncogenic viral infection (e.g., EBV causing transformation of B lymphocytes leading to Burkitt lymphoma; HPV E6/E7 proteins inactivating p53 and Rb; HTLV-1 causing adult T-cell leukemia), accumulation of mutations in proto-oncogenes/tumor suppressor genes, or chromosomal translocations. Clinically, 'transformation' is also used to describe indolent lymphomas progressing to aggressive forms (e.g., follicular lymphoma transforming to diffuse large B-cell lymphoma), which is high-yield for Step 2 hematology/oncology questions.
Sources
- First Aid for the USMLE Step 1
- Sketchy Micro
- Robbins and Cotran Pathologic Basis of Disease
- Molecular Biology of the Cell (Alberts et al.)
Reviewed by AnkiBoss editorial — medical student review. Information here is for study reference only and is not medical advice. Spotted an error? Let us know.