Diffusion and osmosis across a semi-permeable membrane.
Purpose:
Activity A: The purpose of Activity A is to see how different substances act in the diffusion.
Activity B: The purpose of Activity B is to investigate theinfluence (if any) of solute concentration on the movement of water molecules through a semipermeable membrane.
Background Info:
The cell membranes are semipermeable which means that they allow some molecules to pass inside and they block another ones. This molecules pass through the membrane either by active transport (The cell expends energy) or by passive transport (It uses the therman energy of the cell).
In this lab we will investigate the passage of molecules through the semipermeable membrane, this process is called diffusion because it involves molecules moving from areas of higher concentration to areas of lower concentration.
We will also investigate a process called osmosis which is based on the ability that the water has to be able to enter the red blood cells.Normally a red blood cell gains and loses the same amount of water because the solutes is the same. In this case the solutions are called isotonic. If the solute of the plasma would be higher it would be hypertonic and if the solute of the plasma is lower it would be hypotonic.
Hypothesis:
Activity A)
1- If the solution outside the bag tests positive for glucose, then glucose diffused out of the dialysis bag and through the permeable membrane.
2- If the solution outside the bag is black then the starch has diffused.
3- If the solution inside the bag is black then the iodine has diffused.
Activity B)
1- If the weight inside the dyalisis bag is greater than what it was before the the water has diffused inside and if the weight is smaller, then the water has diffused out.
Materials and Equipment:
Activity A) Dialysis tubing, plastic cup, glucose/starch solution, distilled water, iodine (IKI) solution, dropping pipet, glucose test strips, funnel.
Activity B) Dialysis tubing, plastic cups, distilled water, funnel, sucrose solutions, paper towels, balance, calculator.
Methods:
Activity A) -Pour 160-170 mL of distilled water into a plastic cup.
-Add aproximately 4mL of IKI solution.
-Record if there is glucose or not.
-Record if there is glucose or not in the glucose/starch solution
-Pour 15mL of the glucose/starch solution into the dialysis tubing and close it so thatit forms a bag.
-Inmerse the dialysis bag in the solution in the cup.
-Wait for 30 minutes and check the colors and the glucose again.
Activity B)
-Pour 160-170 mL of distilled water into a plastic cup.
-Pour 15 mL of the sucrose solution into a dialysis bag and close it.(Tie it off)
-Record its mass (The mass of the dialysis bag with the sucrose solution on it).
-Inmerse the dialysis bag in the water in the cup.
-Wait for 30 minutes and record its final mass.
-Calculate the percent change in mass and record it in the table.
Results and Analysis:
Activity A)
The initial solution in the dialysis bag (glucose/starch solution) was clear and positive in glucose while the final solution in the same dialysis bag was black and also positive in glucose.
The IKI solution in the cup was brown at first and continued brown at the end but the glucose went from being negative at first to becoming positive at the end.
Activity A: The purpose of Activity A is to see how different substances act in the diffusion.
Activity B: The purpose of Activity B is to investigate theinfluence (if any) of solute concentration on the movement of water molecules through a semipermeable membrane.
Background Info:
The cell membranes are semipermeable which means that they allow some molecules to pass inside and they block another ones. This molecules pass through the membrane either by active transport (The cell expends energy) or by passive transport (It uses the therman energy of the cell).
In this lab we will investigate the passage of molecules through the semipermeable membrane, this process is called diffusion because it involves molecules moving from areas of higher concentration to areas of lower concentration.
We will also investigate a process called osmosis which is based on the ability that the water has to be able to enter the red blood cells.Normally a red blood cell gains and loses the same amount of water because the solutes is the same. In this case the solutions are called isotonic. If the solute of the plasma would be higher it would be hypertonic and if the solute of the plasma is lower it would be hypotonic.
Hypothesis:
Activity A)
1- If the solution outside the bag tests positive for glucose, then glucose diffused out of the dialysis bag and through the permeable membrane.
2- If the solution outside the bag is black then the starch has diffused.
3- If the solution inside the bag is black then the iodine has diffused.
Activity B)
1- If the weight inside the dyalisis bag is greater than what it was before the the water has diffused inside and if the weight is smaller, then the water has diffused out.
Materials and Equipment:
Activity A) Dialysis tubing, plastic cup, glucose/starch solution, distilled water, iodine (IKI) solution, dropping pipet, glucose test strips, funnel.
Activity B) Dialysis tubing, plastic cups, distilled water, funnel, sucrose solutions, paper towels, balance, calculator.
Methods:
Activity A) -Pour 160-170 mL of distilled water into a plastic cup.
-Add aproximately 4mL of IKI solution.
-Record if there is glucose or not.
-Record if there is glucose or not in the glucose/starch solution
-Pour 15mL of the glucose/starch solution into the dialysis tubing and close it so thatit forms a bag.
-Inmerse the dialysis bag in the solution in the cup.
-Wait for 30 minutes and check the colors and the glucose again.
Activity B)
-Pour 160-170 mL of distilled water into a plastic cup.
-Pour 15 mL of the sucrose solution into a dialysis bag and close it.(Tie it off)
-Record its mass (The mass of the dialysis bag with the sucrose solution on it).
-Inmerse the dialysis bag in the water in the cup.
-Wait for 30 minutes and record its final mass.
-Calculate the percent change in mass and record it in the table.
Results and Analysis:
Activity A)
The initial solution in the dialysis bag (glucose/starch solution) was clear and positive in glucose while the final solution in the same dialysis bag was black and also positive in glucose.
The IKI solution in the cup was brown at first and continued brown at the end but the glucose went from being negative at first to becoming positive at the end.
Allele shuffling of single gene traits in Drosophila.
This experiment has been conducted to see how the genetics of the parent Drosophila affect to their children and see if the genes are passed randomly or if they follow a pattern.
The experiment will begin by observing the phenotypes of wild-type flies and distinguishing male from female; after that they will be crossed and the results from the small flies will be observed.
If the p-value is greater than 5%, then allele shuffling can be said to be random.
For the successful completion of this experiment drosophila will be used. Another materials such as sorting brushes, sorting cards, fly morgue, stereomicroscope and mashed potatoes will also be used.
The first step will be to analyze and contrast the phenotypes of the wild-type flies with the mutants. The next step will be to sex them. After a short period of time, the offspring (F1) will be analyzed. The next step will be to remove the F1 generation and analyze the F2. After that the Chi-Square Test will be used to see how the first generation affected the F2.
The data was pretty different in each of the three crosses. In the first one which was between VvSs and VvSs; the data was found to be significant which means that the genes influenced on the F2 generation. In the second cross, which was between Wild and White eyed females and males;the data was found to be significant too; which means that the genes also affect to the sex and not only to the phenotypes. The third cross, which was between Ss and Ss was not significant which means that in this case the parents didn't influence their children.
After doing this experiment;the conclusion that is taken is that in the most of the cases the allele shuffling is not random for example the parents affected their children in the sex and in the color of the eyes in the second cross. The results taken after analyzing how the genes of the Drosophila are given helps the world in a way in which we can easier identify how our children will be. I don't feel very confident about this results, basically because I didn't understand anything about this lab. A way that would help me feeling more confident would be by going slower in every step and taking more care about what was going on.
excel_charts.xlsx | |
File Size: | 11 kb |
File Type: | xlsx |