What is the first step in preparing a crude extract?

Choosing the correct cell or tissue source is indeed the first step in preparing a crude extract because it determines the availability and type of proteins, enzymes, or metabolites that will be present in the final extract. Selection of the appropriate biological material is critical, as different cells or tissues will yield different biochemical components based on their unique physiological and chemical makeup.

For instance, if you are interested in isolating a specific enzyme or protein, you need to choose a cell type or tissue that is known to express that protein at significant levels. This foundational step sets the stage for subsequent processes like cell lysis and centrifugation, which are aimed at extracting and purifying the target molecules. If the source is not suitable, the whole extraction process may yield poor results or might not provide the desired biomolecule at all.