Unit 3 Reflection

This unit was about cells, their structure, and their function. It was also about the concepts of photosynthesis and cellular respiration. My strengths are the function of cells and all their parts. I know the organelles by heart (ribosomes, nucleus, ER, Golgi body, mitochondria, cell wall, cell membrane, cytoplasm, lysosome, chloroplast, etc.) I know the functions of all these organelles and how they complement each other. At first I didn't understand diffusion at all, but the egg diffusion lab really helped me understand it better. I got a wider understanding of hypertonic and hypotonic solutions. I really learned how diffusion affects a cell's size. I understand photosynthesis a little better after Mr. Orre explained it in detail with the diagrams in class. However, my weakness in this unit is cellular respiration. I get the products and reactants, but I don't understand the details of it yet. Maybe to study, I will watch Mr. Orre's vodcast again and draw diagrams without my notes and label them. The lab with the microscope was really fascinating to me because I got to see some organelles up close with different cells. I am still curious about what ribosomes look like, although they are very hard to see with our microscopes. I want to learn more about the process of photosynthesis because it really fascinates me. I look forward to the next unit.

Egg Diffusion Lab

The purpose of this lab was to find out how a cell's internal environment changes as its external environment changes. We took two eggs that were both dissolved in vinegar to dissolve the shell and expose the membrane, and we put one of them in deionized water and one of them in sugar water. We took the mass and circumference of each egg before we placed them in the solutions, and took the same measurements after we put them in the solutions. Them we knew if the cell shrunk or grew in the different solutions, so we would have a conclusion for our question. 

Our class data showed that the mass and circumference decreased as the sugar concentration increased. Because the cell had more water(solvent) in it than the outside and passive diffusion goes from high concentration to low concentration, or in other words, the sugar water was a hypertonic solution, the water diffused out of the cell, and as a result, the cell shrunk.  

A cell's internal environment as its external environment changes. If the external environment has many solutes in  it, then the water will diffuse out of the internal environment of the cell and make the cell shrink. Meanwhile, if there a little or no solutes in the external conditions, then the water diffuses into the internal environment of the cell and makes the cell grow. This is all because of the concept of diffusion and the different types of solutions. Vinegar is a hypotonic solution, where there was more water outside than inside the cell, so the egg grew from when it had its cell.   

This lab demonstrated the concentration of diffusion, which we also learned in class. We learned that when its a hypertonic solution, water diffuses out and the cell shrinks, and when it is hypotonic, the water diffuses in and the cell grows. 

This lab can also relate to real life.Fresh vegetables are sprinkled with water because the water is hypotonic, so the vegetable becomes bigger which makes it more appealing. Salt along roadsides kill plants because salt is hypertonic, which will make the plant cells shrink. When they shrink, they can't function which also means the plant can't function. 

If I were to test another thing based on this, I would test the affect on salt water on the body. I would want to see what exactly happens to the human cell. 

Egg Macromolecules Lab

For this lab, we asked the question, " Can macromolecules be identified in an egg cell?" We found that in an egg yolk and an egg membrane, monosaccharides were present. Lastly, we found out that in an egg white, proteins are present. In the monosaccharide test, both egg yolk and the egg membrane tested positive. In the egg yolk test, it turned blue, but also with a hint of green. With the membrane, it turned to almost complete blue. This evidence supports our claim because for a monosaccharide to be present, the solution had to turn blue, and for those two parts, it did. In the polysaccharide test, the egg white tested positive. The solution turned to a darker blue and almost purple color. This supports our evidence because for it to have proteins, it had to turn form blue to purple, and it did.

One possible error in this experiment could have been the perception of color from different eyes. If I thought that a dark blue was not close enough to purple, I could have said that proteins were not present in the egg yolk, but if someone else decides that it is basically purple, they can say that proteins are present in an egg yolk, which would lead to two different results. One way to fix this error is to possibly have a scale and compare your solution to that one. This will lead to more consistent results throughout the class. Another error that could have occurred is that egg was not separated properly into the different test tubes. For example, the egg membrane could have mixed with the yolk and when the solution was added there could have been an extra color change. This could tell the analyzer that there is a specific macromolecule in the yolk, when the macromolecule was not supposed to be found there. One recommendation is when you are separating the egg yolk, you can use a strainer to get only the yolk.

The purpose of this lab was to find out what macromolecules are in the different parts of an egg cell. In class, we learned about the different macromolecules and their function, and this lab tells us where they are located in an egg cell. We now know what types of macromolecules we are getting when we eat an egg. This could be applied in putting macromolecules in other foods that have egg contents. I look forward to learning more about macromolecules in the future.