The electronic transitions of the peptide bond occur in the far UV. The intense peak at 190 nm, and the weaker one at 210–220 nm is due to the p ® p* and n ® p* transitions.

TLS Online TPP Program

#Id: 4244

#Unit 12. Applied Biology

The culture medium provides the necessary nutrients, growth factors, and hormones for cell growth, as well as regulating the pH and the osmotic pressure of the culture.

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#Id: 4246

#Unit 12. Applied Biology

Serum in culture media regulates cell membrane permeability and serves as a carrier for lipids, enzymes, micronutrients, and trace elements into the cell. 

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#Id: 4249

#Unit 12. Applied Biology

The most common antibiotics used are penicillin and streptomycin, which inhibit a wide spectrum of Gram-positive and Gram-negative bacteria. Penicillin acts by inhibiting the last step in bacterial cell wall synthesis while streptomycin blocks protein synthesis.

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#Id: 4250

#Unit 12. Applied Biology

The pH indicator phenol red is used for monitoring the status of the medium. This will change from red at pH 7.2–7.4 to yellow or fuchsia as the pH becomes either acidic or alkaline, respectively.

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#Id: 4254

#Unit 12. Applied Biology

Phenol Red

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#Id: 4256

#Unit 12. Applied Biology

Passaging, is the removal of the medium and transfer of cells from a previous culture into fresh growth medium, a procedure that enables the further propagation of the cell line or cell strain.