Biotechnology

EGF is a primary mitogenic growth factor that stimulates cell proliferation. While other factors support cell survival, EGF is specifically responsible for promoting cell division in mammalian cultures.

Mammalian cells require a pH of 7.2-7.4 (physiological pH) for optimal growth. This is maintained using buffers like bicarbonate or HEPES in culture media.

Continuous cell lines (like HeLa, CHO) have unlimited replicative potential due to telomerase activation or genetic modifications, allowing indefinite division unlike primary cultures.

Laminar flow hoods create unidirectional airflow through HEPA filters, maintaining a sterile environment and preventing microbial contamination during cell culture operations.

DMEM is the most widely used culture medium for mammalian/animal cell culture due to its balanced nutrient composition. LB broth is for bacteria, PDA for fungi, and Czapek Dox for fungi.

dNTPs (dATP, dGTP, dCTP, dTTP) are incorporated into the growing DNA strand by Taq polymerase via phosphodiester bond formation.

Each PCR cycle doubles the DNA amount (exponential amplification). After 30 cycles, theoretical amplification = 2^30 ≈ 10^9 fold increase.

Denaturation occurs at 94-95°C where hydrogen bonds between complementary DNA strands break, separating double-stranded DNA into single strands.

Taq polymerase, derived from Thermus aquaticus, is a heat-stable DNA polymerase that extends primers during PCR elongation at 72°C.

dNTPs (deoxynucleotide triphosphates) are the precursor molecules that DNA polymerase incorporates into the growing DNA strand during the extension phase of PCR.