The purpose of experiment part 1A was simple, to measure diffusion of small molecules through dialysis tubing. Dialysis tubing is a type of semi-permeable membrane tubing[1] used in separation techniques that facilitates the removal or exchange of small molecules from macromolecules in solution based on differential diffusion. In the context of life science research, dialysis tubing is typically used in the sample clean-up and processing of proteins and DNA samples or complex biological samples such as blood or serum. Dialysis tubing is also frequently used as a teaching aid to demonstrate the principles of diffusion, osmosis, Brownian motion and the movement of molecules across a restrictive membrane.
The initial purpose of lab 1A was to measure the diffusion of small molecules through the selectively permeable dialysis tubing. My group concluded that the glucose was able to leave the tubing.
1B
Lab Part 1B
Purpose: We set out to discover the relationship between solute concentrations, selectively permeable membranes and the way they react with osmosis.
Introduction: Osmosis is the movement of water from a high concentration to a low concentration, trying it’s best to reach equilibrium. When or if the concentration outside of the membrane is more concentrated compared to the inside of the membrane, water will move out to even the concentration out. Selective permeability refers to the ability of that cell or objects to decide what can and cannot enter but either way it always unsuccessfully striving to reach equilibrium with its surroundings.
Methods: We tied up six presoaked dialysis tubing bags and filled them up with the following concentrations of sucrose:
a) Distilled water
b) 0.2 M sucrose
c) 0.4 M sucrose
d) 0.6 M sucrose
e) 0.8 M sucrose
f) 1.0 M sucrose
After that we placed each of the bags in their own cups filled with distilled water for half an hour and then took them out and recorded their new or final masses.
Data, Graphs and Charts:
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Discussion: The data shows a consistent trend between the group and class data until it gets to the 6th where our data differs dramatically from the rest of the class undoubtedly from an error. Otherwise the data would not have jumped from the class average of 9.69 to ours of -2.174. That much difference in percentage change is very extreme. But for the rest of the experiment our data is very useful because it is around the norm but since we had one abnormal point the rest must also be assumed to be faulty and cannot be taken into consideration.
1C
Purpose: The purpose of the lab was to fully understand the concept water potential. Our job was to
use potato cores, and place them in different molar concentrations of sucrose in order to determine the
water potential of potato cells. We wanted to see what would physically happen to potato cores. The
independent variable is the potato cores and molar concentrations. The dependent variable is the
physical outcome of the potato cores features after laying in a high or low molar concentration. We
were really trying to find out the size and weight of the cores after the concentration.
Introduction: Intro into this lab is water potential. The definition of water potential is potential energy of water relative to pure water in reference conditions. Water will always move from an area of high water potential to an area of lower water potential. Water potential can be affected by 2 physical factors. Which are the addition of solute which lowers the water potential, and pressure potential with is physical pressure.
Methods: To start the lab we had to cut up 3 cores of potato for each cup that contained a certain amount of concentration. The potato cores had to be congruent to each other. We placed 3 cores in each cup. Then we covered the cups, and let them stand over the night. The next day we uncovered the cups and took the cores out of the cups. We weighed the cores. The lower the concentration the heaver the potato cores weighed. As we got to a higher concentration the lighter the cores were. The physical outcome of the core was that the more concentration the more fragile the cores were.
Introduction: Intro into this lab is water potential. The definition of water potential is potential energy of water relative to pure water in reference conditions. Water will always move from an area of high water potential to an area of lower water potential. Water potential can be affected by 2 physical factors. Which are the addition of solute which lowers the water potential, and pressure potential with is physical pressure.
Methods: To start the lab we had to cut up 3 cores of potato for each cup that contained a certain amount of concentration. The potato cores had to be congruent to each other. We placed 3 cores in each cup. Then we covered the cups, and let them stand over the night. The next day we uncovered the cups and took the cores out of the cups. We weighed the cores. The lower the concentration the heaver the potato cores weighed. As we got to a higher concentration the lighter the cores were. The physical outcome of the core was that the more concentration the more fragile the cores were.
This graph show the class average versus our group data of the sucrose amount and the mass of potato
cores.
Discussion: From looking strictly at our data chart it shows the initial mass of the potato cores, and then the final mass. The first row was with no sucrose, just distilled water. Then next column started with 0.2,0.4 ,0.6, 0.8, and 1.0 molar sucrose. We predicted that the potato cores that stayed in a high concentration would have a higher percent of change in mass than a low concentration. As you can observe, the mass of the potato cores with a low concentration had a higher final mass compared to higher concentration. Then the mass of the potato cores with a higher concentration had a lower final mass. So we hypothesized correctly what would happen to the masses of the potato cores in a high and low concentration. The percentage of change in mass started off with positive percentage then as the sucrose level got higher the percentage became negative. The percentage getting as high as 36.84%. One trend we notice was that in distilled water and 0.2 sucrose the final masses were higher than their initial mass. Looking back on the experiment I don’t think there is any invalidity on this trend. This experiment was considered a success because we correctly tested what we wanted to learn. Also we got the results we wanted and predicted. The results support our hypothesis.
Conclusion: The end result of the lab was that if there was enough solute is added to the water outside the cells, water will leave the cells. This means moving from an area of higher water potential to an area of lower water potential. When cell losses water it will cause lost of turgor. Loss of water continuously will cause the cell membrane to shrink away from the cell walls. The data we recorded of the potato weight showed a decline in weight from a high molar concentration. The data concludes that we did the experiment right.
"Water and Solute Potential Boundless Open Textbook." Boundless. N.p., n.d. Web. 25 Oct. 2014.
"Water Potential." Wikipedia. Wikimedia Foundation, 10 June 2014. Web. 24 Oct. 2014.
Discussion: From looking strictly at our data chart it shows the initial mass of the potato cores, and then the final mass. The first row was with no sucrose, just distilled water. Then next column started with 0.2,0.4 ,0.6, 0.8, and 1.0 molar sucrose. We predicted that the potato cores that stayed in a high concentration would have a higher percent of change in mass than a low concentration. As you can observe, the mass of the potato cores with a low concentration had a higher final mass compared to higher concentration. Then the mass of the potato cores with a higher concentration had a lower final mass. So we hypothesized correctly what would happen to the masses of the potato cores in a high and low concentration. The percentage of change in mass started off with positive percentage then as the sucrose level got higher the percentage became negative. The percentage getting as high as 36.84%. One trend we notice was that in distilled water and 0.2 sucrose the final masses were higher than their initial mass. Looking back on the experiment I don’t think there is any invalidity on this trend. This experiment was considered a success because we correctly tested what we wanted to learn. Also we got the results we wanted and predicted. The results support our hypothesis.
Conclusion: The end result of the lab was that if there was enough solute is added to the water outside the cells, water will leave the cells. This means moving from an area of higher water potential to an area of lower water potential. When cell losses water it will cause lost of turgor. Loss of water continuously will cause the cell membrane to shrink away from the cell walls. The data we recorded of the potato weight showed a decline in weight from a high molar concentration. The data concludes that we did the experiment right.
Reference:
"LabBench." LabBench. N.p., n.d. Web. 22 Oct. 2014.
"LabBench." LabBench. N.p., n.d. Web. 22 Oct. 2014.
"Water Potential." Wikipedia. Wikimedia Foundation, 10 June 2014. Web. 24 Oct. 2014.
1E
Discussion: From this lab the results we got described the effects of high concentrated solutions on diffusion and cellular contents. Only the definition of plasmolysis helped this experiment. This is shrinking of the cytoplasm of a plant cell in response to diffusion of water out of the cell and into a hypertonic solution surrounding the cell. The description of what the wet mount small piece of epidermis on the onion looked like is a very clear cell membrane. Then the drops of 15% NaCl makes the picture look completely different. Then results of the lab were good and correct. We properly did this experiment and the results are fitting. The validity of the experiment is correct proving that the experiment was a success.
Reference:
-"Microscopy." Microscopy. N.p., n.d. Web. 26 Oct. 2014.
-N.p., n.d. Web.
-"Plasmolysis of Red Onion Cells." MicrobeHunter Microscopy Magazine. N.p., n.d. Web. 26 Oct. 2014.
-"Plasmolysis." Wikipedia. Wikimedia Foundation, 16 Oct. 2014. Web. 26 Oct. 2014.
- Video taken from YouTube
- Picture from Google Images
