A culture of 50 mL holds 200 million bacterial cells in every millilitre…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
A culture of mL holds million bacterial cells in every millilitre. Every cell carries copies of a plasmid with the cloned gene.
- How many cells are in the culture?
- How many copies of the gene are in the whole culture?
- The same gene is moved to a vector with copies in each cell. How many times more copies does the same culture hold?
Need a reminder? The key ideaShow
A vector needs an origin of replication, a selectable marker and cloning sites, few of them and best of all one for the enzyme in use. DNA ligase joins ends that fit. Copies of the gene in a culture copies of the plasmid in one cell the number of cells.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Given. mL; million cells/mL; copies per cell.
Plan. Cells cells in one mL volume. Copies cells copies per cell.
Step 1. (a) billion cells.
Step 2. (b) billion billion copies.
Step 3. (c) With copies per cell: billion billion. The ratio is times.
Answer: billion cells; billion copies; times.
Check. The number of cells did not change, so the ratio of the copies is the ratio of the copy numbers.
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