Please show work or explain, thank you. 1) For an elemental analysis, a chemist

Question

Please show work or explain, thank you.

1) For an elemental analysis, a chemist asks for 10 mg of dried cells of M. extorquens. M. extorquens can be easily grown to an optical density of OD 1 (about 1049 cells/mL) How many liters of cells do you need to grow to obtain the 10 mg of dried cells requested? Please show work. 2) Which of the peptides listed below cannot be distinguished by peptide mass fingerprinting analysis using trypsin? Please explain why. YERSINIAPESTIS ESCHERICHIA SCHEERACHII CHEERSICHIA ERSCHEACHII

Explanation / Answer

Hi,
The turbidity to dry mass conversion follows the rule of thumb, an OD 1 equals approximately 1g/l of the dry cell.

Here, the chemist is asking for 10mg of dried cells. So 10 ml (0.01l) is sufficient to give 10mg of dry mass.

2. The trypsin cuts after every Arginine (R) and Lysine (L) if not immediately followed by Proline(P). In all the given options, at least one R is present and hence the trypsin can create one cleavage at C-terminal of R amino acid and give two fragments.

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