Unit 3 reflection

This unit was about what is inside a cell, and what cells do. It included photosynthesis, cellular respiration, and osmosis. This unit also mentions how cells were discovered, and how cells changed over time. The main theme of this unit was that cells are the building blocks, and the ways cell use their organelles, and processes to communicate, and survive, and create life. One other key concept was how the structure of a cell affects its function. My main strength was the organelles, and osmosis, because I feel like I really understand them, and can explain them. My main weaknesses would be photosynthesis and cellular respiration, because while I mostly understand them, there are a few details I still don't understand fully.

I learned a lot about cells, and also about good lab procedure. I learned how to find errors in an experiment, and come up with ways to fix them. I also got a little better at getting through the vodcasts without pausing. Finally I learned new ways to get through difficult material.

I still want to learn more about photosynthesis, and how it works at a deeper level. At a more broad level I find it amazing how life evolved from tiny bacteria to big multi-cellular organisms that will have the capability to learn, and study the tiny cells they are made of. I also love concept of osmosis, and how quickly a cell will change based on its surroundings. If I have time I might try duplicating one of the experiments at home, but with slight modifications.










I normally study minimally for test, but for this one I plan to at the minim review photosynthesis and cellular respiration through the CFUs, vodcast notes, and the diagrams. I will also take the CFUs again, and review any other difficult concepts based on what I get wrong.

Egg diffusion lab

In this lab we took two eggs, and put them both in vinegar to dissolve the eggshell, and expose the membrane. After two days we took them both out of the vinegar, and put them into de-ionized water for a few more days, then after measuring their mass and circumference, placed one in sugar water, and one in de-ionized water. We then waited two days, measured their mass, and circumference again.

The cell that was placed in the hypertonic solution(sugar water) shrunk. Its mass decreased by 51.7%, and its circumference decreased by 23.67%. This was caused by the water in the cell wanting to diffuse from high concentration(the cell), to low concentration(the sugar water), and the sugar wanting to defuse into the cell,but being blocked by the membrane. The cell that was placed in the hypotonic solution grew. Its mass increased by .176%, and its circumference increased by .201%. This was caused by the water in the cell wanting to passively diffuse from high concentration(the DI water), to low concentration(the cell), and the minerals wanting to defuse into the cell,but being blocked by the membrane.

A cell's internal environment changes, as its external environment changes, because it naturally wants to maintain equilibrium, and because of that the cell will try to take in everything around it , until the concentration inside, and outside of the cell is the same. It does this through diffusion.

This lab demonstrates diffusion, and how solutes, and solvents want to move along the concentration, and the effect this has on the cell. 

Fresh vegetable are sprinkled with water, because water is hypotonic, and will want to diffuse into the cells of the vegetable, which will make the vegetable bigger, which will in turn make it look better, and make more people want to buy it. Also, when road are sprinkled with salt, the plants along the side die because the salt is hypertonic, and will make the cells in the plant shrink and lose functionality.

Based of this lab, I would want to do a lab to determine the effects of salt water on a cell, versus mineral water. 

Egg Macromolecules

In this lab we looked a cell to determine which macro molecules are found in which parts of the cell. To do this we took an egg, and separated it into the yolk, white, and membrane. We then took each of these three components and used chemical identifiers to determine which macro molecules were  in which parts of the cell. We found that proteins are found in the egg white. This was shown, by when we added sodium hydroxide (NaOH) and copper sulfate (CuSO4), to the sample, and it turned a dark blue, which is an indicator that a protein is present. This makes sense, because egg whites are the food for the growing embryo, and cells need proteins to grow. The membrane contains lipids. We know this because, when we added Sudan III to the lipid it turned orange, which is a sign that a lipid is present. This data makes sense because all membranes are made of lipids. We also found lipids in the egg yoke.  We know this because, when we added Sudan III to the lipid it dark-ish orange, which is a sign that a lipid is present. This data makes sense because all membranes are made of lipids, and there is a clear membrane surrounding the egg yoke.

 One possible error in this lab was that when we tested the yoke for proteins, the sample turned green,which made it impossible to tell if it contained proteins. To remove this error I would mix the sodium hydroxide (NaOH) and copper sulfate (CuSO4) better. Another error is that when testing the membrane we cut it into one chunk. This only exposes the outside of the membrane, but not the inside. This led to us not finding proteins in the membrane, even though there were proteins in the membrane. To fix this error, I would cut the membrane into more, smaller, pieces before testing it.

This lab was done to further our understanding of macromolecules, and how they the building blocks of life. This relates to macromolecules, and also what makes up the different parts of a cell. This lab can be applied to future leaning about cells, and will allow me to make inferences about which macromolecules make up which parts of the cell.