Question

How many sugars ar needed to provide the energy and construction material fro making a new cell? Make an estimate for the average rate of sugar uptake for dividing bacterium.

Answer 1

Let us assume a case in E.coli:A single E.coli added to 5 mL tube with sterile growth medium and placed in a shaker at 37 °C.

The exponential growth rate is represented as 40 min per division .

E. coli diameter :≈1 μm

length of ≈2 μm (cell size would depend on growth rate).

Water content : ≈70%

dry mass is 0.5 pg .

It is known that the elemental composition of E. coli is that half of its mass is carbon approximately

So, there would be ≈10¹⁰ carbon atoms per cell.

So, we can conclude that single E.coli would requires carbons from sugar/glucose to make a new cell and that would come to ≈2 × 10⁹ sugar/glucose molecules.

Energy requirement:

Under aerobic conditions glucose makes ≈30 ATP molecules.Therefore, the energetic requirement would be ≈3–6 × 10⁸ glucose molecules/sugar molecules

In total ≈3–6 × 10⁸ glucose/sugar molecules. + ≈2 × 10⁹ glucose/sugar mocleules needed for energy and construction material for making a new cell.

An estimate for the average rate of sugar uptake for dividing bacterium:

Dividing bacterium in a generation time would require uptake of 10¹⁰ carbon atoms.Here we would not include sugar for energy production.

So,average rate of sugar uptake for dividing bacteria would be ≈2 × 10⁹ sugar/glucose molecules.