Unit 3 Reflection

In this unit, we learned about cells. First, we learned about the cell theory. It states that all living things are made up of cells,cells are the basic unit of life, and that new cells come form previously existing cells. We also learned about prokaryotic cells vs. eukaryotic cells. Eukaryotic cells have nuclei and many cell organelles. All of these organelles have different, important functions. Nucleus contains the DNA. Ribosomes, rough ER, and the Golgi apparatus all help in producing proteins. The mitochondria help in producing ATP. The chloroplasts (only in plant cells) are where photosynthesis occurs. The cell wall provides support. The cell membrane is a selectively permeable lipid bilayer that allows only certain molecules to pass through using protein channels, osmosis, and diffusion. Diffusion is the movement of cells from areas of high to low concentration. Osmosis is the diffusion of water. Another thing we learned about was photosynthesis and cellular respiration. 

For me, the topic of cell organelles and their functions is the easiest and the best understood. Diffusion and osmosis is understood but a little confusing. The topics of photosynthesis and cellular respiration confuse me the most, and were the more difficult to learn because they have so many steps and molecules involved. I wonder how cells evolved. I really want to learn more about photosynthesis and the nucleus, like how does the DNA inside give the instructions? 

Egg Diffusion lab

In this lab, we put one egg in sugar water and the other in deionized water, to see how a cell's internal environment changes as its external environment changes.
When the sugar concentration increased, the mass and circumference decreased. The cell's mass changed by an average of -47.25% and the circumference changed by an average of -22.94%. The sugar solution is a hypertonic solution because there is more solute outside the cell. Now, there is high solute concentration (sugar) and low solvent concentration (water) outside the cell than inside the cell. To balance the concentration, the water inside the cell diffused to the area outside the cell where there was a low concentration of water. The sugar could not go inside the cell, because the cell membrane is semipermeable and does not allow solutes to pass through since they are too big.

A cell's internal environment changes as the external environment changes to maintain homeostasis. Sometimes, the cell can grow and shrink using diffusion to maintain the concentration gradient. When we put the cell in vinegar, it grew because the solvent concentration outside the cell was high, and in the water it grew even more. However, when we put it in the sugar water, it shrunk because all the water diffused out.

We learned a lot about diffusion, solvents, and solutes and how they help a cell live. One major biological principle we learned in class was passive diffusion and the concentration gradient. This concept is used a lot in real life as well. When roads are salted to melt the ice, it can sometimes cause the plants to shrivel up because there is a lot more solute outside the plants' cells now, so the water inside the cells will leave the cell, causing it to shrink.
One experiment I want to do is to see if all cells will react the same way. I could see if fresh fruits and vegetables react the same way when they are put in sugar water or deionized water.

Eggcellent experiment- Egg Macromolecules Lab

In this lab, we asked the question can macromolecules be identified in an egg cell?
We found that egg yolk tested positive for lipids. When Sudan III was added to the yolk it turned from red to orange, and it turned a very dark orange, indicating that egg yolk has many lipids. Egg yolk may have lipids because lipids make up the thin membrane surrounding the yolk, and is used for energy for growth and development.
Egg white tested positive for proteins and monosaccharides. When tested for proteins, it turned purple, and when tested for monosaccharides, it turned greenish blue. Monosaccharides are used for energy and development. Proteins contain the enzymes needed to break down the carbohydrates for energy, and it can also be used for growth and a last line of immunity.
Egg membrane tested positive for polysaccharides, proteins, and lipids. When tested for polysaccharides it turned a very dark brown. When tested for proteins, it turned purple. When tested for lipids it turned a light orange. Polysaccharides are found on the surface of cells to communicate. Proteins are used as transport proteins in the cell membrane. Lipids (phospholipids) make up the membrane.

There could have been some errors due to difficulty of separating the eggs parts and bias towards the color. It was very difficult to separate the different egg parts completely. The yolk and the egg membrane mixed a little, so the egg white tested positive for some macromolecules that should not have been there, such as monosaccharides. The bias towards color could have also resulted in some errors. Our data said that certain parts tested positive because they turned a certain color, but it could have been a different color, but someone thought it was another color, or a deeper/ lighter shade. For example, with the polysaccharides it was hard to determine what turned "black" and what was "brown". I would recommend having a better way to separate the egg, rather than poking it open, such as rinsing the egg membrane to wash off any yolk/white that is on it, and gently separating the yolk and white. To eliminate the bias, more than two or more people should determine the color, or there is already a sample of a macromolecule that has been tested to compare our sample to.

The purpose of this lab was to identify the different macromolecules avaliable in certain parts of a cell. In class, we learned about the different macromolecules and cell organelles and how the are related, and we re-enforced that concept with this lab. Based on my experience from this lab, I know understand more about how cells work, and why eggs have the layers and macromolecules that they do.

Identifying questions and hypothesis

I found a study saying that many people are missing certain genes, and the variation depends on what part of the world that person comes from.The question is: Do people all have the same genes, and if not then is it problematic? The hypothesis is: If several people around the globe can have over 200 missing genes, then it is not problematic.

To read the ful article click here:
http://www.sciencedaily.com/releases/2015/10/151001094723.htm