Question

The concentration of a biomolecule inside a rod-shaped prokaryotic cell is 0.0029 m. calculate the number of molecules inside the cell, which is 4.9 μm long and 1.2 μm in diameter.

Answer 1

Molarity is expressed as:
Molarity = moles / liter

Given that the cell is rod-shaped, its volume is calculated using the formula for a cylinder's volume:

V = πr²L
V = π * (0.6)² * 4.9
V = 5.54 μm³

1 Liter = 10³ mm³
1 mm = 10³ μm
1 mm³ = 10⁹ μm³
1 liter = 10¹² μm³

So the volume in liters is:
5.54 x 10⁻¹² L

Moles = molarity * liters
Moles = 0.0029 * 5.54 x 10⁻¹²
Moles = 1.61 x 10⁻¹⁴

To get the number of molecules, we multiply the moles by Avagadro's number

Number of molecules = 1.61 x 10⁻¹⁴ * 6.02 x 10²³

There are 9.69 x 10⁹ molecules in the cell