Exactly what irked me xD

also talking about "sterilizing" with 70% ethanol....instead of using the right term "disinfecting".

Yes, seems as if that is so, I'd be inclined to provide reusable glassware and a proper sterilization procedure and not use the single use plastic supplies - but the whole environmental cost/benefit from origin should be analysed when making that social decision (rather that basing that on the local business budget only).

i have never lost a pellet in this way.

This is a generic protocol and is meant as an introduction to the idea of cell culture and aseptic technique. This, as with other protocols may be adjusted to suit the requirements of the specific experiment undertaken/cells in use. However, It is common practice to centrifuge and resuspend cells after trypsinisation and this does not affect cell viability when done under appropriate conditions (e.g. normal levels of pipetting with a standard opening tip does not generate sufficient shear force to damage mammalian cells) You are correct that most cells are largely unaffected by simply leaving the trypsin on, diluted. The key point is that not performing the centrifugation step is really only appropriate where routine subculture is being undertaken. Centrifugation and resuspension is a critical step in a number of cases, e.g. Should the cells need to be completely “washed” of the media they are in, going into a short-term biological assay, the cell sample requires concentration to make a higher cell density. and so the decision for this training video was to include the centrifugation step.

I see, thanks!

its a laminar flow

not reqd in mammalian cell culturing most of the time