Let us consider a bacterial cell that depends on chemical reactions using oxygen to produce energy. The cell needs to obtain molecular oxygen from the extra-cellular medium by diffusion through the cell membrane. We model the cell as a water-filled sphere of radius 1 µm. This means that we neglect the presence of the internal structures of the cell: nucleus, nutrients, etc. The oxygen diffusion coefficient (O2) in water at 25°C is 1.0x10-5 cm².s'. Figure 1: Transmission electron microscope Reminder: The distance travelled by diffusion can be picture of a bacterium. from Wikipedia: written as L(t) = V6Dt, where D is the diffusion coefficient and t the diffusion time. "Transmission Electron Microscopy"/ 2. Diffusion as a function of time People have measured the distance travelled by the oxygen molecule in water as a function of time. The results are given in the table below. 0.1 t(s) L (x10“m) log10(1) log1o(L) 0.001 0.005 0.01 0.05 2.45 5.4 7.7 17.3 25.5 Draw the plot of L as a function of time on graph paper (you can use the top of the graph paper sheet appended).

Let us consider a bacterial cell that depends on chemical reactions using oxygen to produce energy. The cell needs to obtain molecular oxygen from the extra-cellular medium by diffusion through the cell membrane. We model the cell as a water-filled sphere of radius 1 µm. This means that we neglect the presence of the internal structures of the cell: nucleus, nutrients, etc. The oxygen diffusion coefficient (O2) in water at 25°C is 1.0x10-5 cm².s'. Figure 1: Transmission electron microscope Reminder: The distance travelled by diffusion can be picture of a bacterium. from Wikipedia: written as L(t) = V6Dt, where D is the diffusion coefficient and t the diffusion time. "Transmission Electron Microscopy"/ 2. Diffusion as a function of time People have measured the distance travelled by the oxygen molecule in water as a function of time. The results are given in the table below. 0.1 t(s) L (x10“m) log10(1) log1o(L) 0.001 0.005 0.01 0.05 2.45 5.4 7.7 17.3 25.5 Draw the plot of L as a function of time on graph paper (you can use the top of the graph paper sheet appended).