Simple Diffusion: Lab Activity

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Activity 1: Simple diffusion
Introduction:
Simple diffusion is the net movement of substances from a region of high concentration to a region of low concentration so its overall net movement is along the concentration gradient, simple diffusion does not require energy therefore it is 'passive', substances are diffused across the membrane between the phospholipids. Materials and methods:

* 20 mwco dialysis membrane
* 50 mwco dialysis membrane
* 100 mwco dialysis membrane
* 200 mwco dialysis membrane
* Membrane holder
* NaCl concentration
* Urea
* Albumin
* Glucose
* Deionized water
* Beakers

The experiment wasn’t done in an actual lab, but rather using a computer simulation in order to achieve precision and save time. Results:
At 20 MWCO ,NaCl (9.00 mM) no diffusion occurred .
At 50 MWCO, NaCl(9.00 mM) diffusion occurred from the left beaker to the right until reached equilibrium was reached. Equilibrium occurred in 10 minutes as NaCl decreases from 9.00 mM to 4.50 mM. Whereas glucose, urea and albumin at 20 and 50 MWCO , didn’t undergo diffusion. This implies diffusion occurs only in NaCl, which means that the membrane is permeable to NaCl at 50 MWCO.

Below is a table showing whether or not diffusion occurred using each dialysis membrane: ( + for diffusion, - for no diffusion) Chart 1| Dialysis Results ( average diffusion rate in mM/min)Membrane(MWCO)| Solute| 20| 50| 100| 250|

NaCl| -| +| | |
Urea| -| -| | |
Albumin| -| -| | |
Glucose| -| -| | |

Discussion:
While undergoing this study , It shows us that NaCl diffuse into the right beaker from the left when it was 50 MWCO . Thus ,NaCl at 20 MWCO didn’t diffuse while all of urea ,albumin and glucose didn’t diffuse at either beakers. Urea diffused in 16 minutes to the right beaker using the 100 MWCO . We conclude that the 100 MWCO is permeable to urea.

On the other hand, we set up NaCl in the left and right beaker in order to make a balance and equilibrium, and to unchange the NaCl solution. Thus, urea had diffused in 100 MWCO at 16 minutes.

Activity 2: Facilitated diffusion
Introduction:
Facilitated diffusion is when a molecule cannot just passively diffuse across a membrane; however, it requires a protein "carrier" and energy in the form of ATP to move across the membrane. Materials and methods:

* Membrane holder
* NaCl concentration
* Glucose
* Deionized water
* Beakers
* Membrane builder

The experiment wasn’t done in an actual lab, but rather using a computer simulation in order to achieve precision and save time. Results:
When glucose at left beaker was set to 2.00 mM:
* When the membrane contained 500 glucose carrier proteins, diffusion of NaCl occurred in 43 minutes. NaCl diffused into the second beaker until equilibrium was reached. * When we built a membrane with 700 glucose carrier proteins, diffusion was faster and ended in 33 minutes. * And when the membrane had 900 glucose carrier proteins, it took 27 minutes.

When glucose at left beaker was set to 8.00mM:
* When we placed the membrane with 500 glucose carrier proteins, the glucose diffused in 58 minutes. * When we placed membrane with 700 glucose carrier proteins, glucose diffuses in 43 minutes. * Finally when we placed a membrane with 900 glucose carrier proteins , glucose diffuses in 35 minutes. . Below is a table showing the facilitated diffusion results: ( + for diffusion , - for no diffusion) Chart 2| Facilitated diffusion results (glucose transport rate, mM/min)| Glucose concentration(mM)| 500| 700| 900|

2.00| +(in 43 minutes)| +(in 33 minutes)| +(in 27 minutes)| 8.00| + (58 minutes)| + (43 minutes)| + (35 minutes)|

Discussion:
We conclude from the experiment that as the number of protein carriers increased, the rate of diffusion increased. Thus NaCl is a control and at equilibrium, so no diffusion occurs....
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