Cell Membrane Structure

A Cell is composed of two distinctive environments: Hydrophilic aqueous cytoplasm and hydrophobic lipid membranes. Lipid environment is defined by the family of molecules that are characterized by their hydrophobic nature and their common metabolic origin. Lipid molecules are slightly soluble to insoluble in water. Lipids are hydrophobic because the molecules consist of long, 16-18 carbon, hydrocarbon backbones with only a small amount of oxygen containing groups. Serve many functions in organisms. Major components of waxes, pigments, steroid hormones, and cell membranes. Fats are synthesizes from two different classes of molecules: fatty acids attached to the alcohol glycerol. Fatty acids are usually 16-22 carbons long. There are 2 different types of fatty acids, saturated and unsaturated. Saturated fatty acids have no carbon- carbon double bonds, while unsaturated fatty acids have one to three double bonds along the backbone carbon chain. Double bonds introduce kinks in the carbon chain that have important consequences on the fluid nature of lipid membranes. Unsaturated fatty acids have lower melting points than saturated fatty acids. To construct a fat, 3 fatty acid molecules are attatched to the glycerol through an ester bond between the carboxyl group of the fatty acids and the three alchohol groups of a glycerol molecule.  A fat molecule can be composeed of1-3 different types of fatty acids each of which can be saturated or unsaturated. Saturated Fatty acids are usually 16-22 carbons long. Fat stores energy and insulates molecules. Saturated fats don't have any.
     Phospholipids contain two fatty acids attached to the glycerol head. A third alcohol of the glycerol forms an ester bond. Being a triprotic acid, the phosphate head has the potential to form ester links with a variety of other types of molecules like amino acids or carbohydrates.

    This a poster of a Fluid Mosaic Model that i drew with another person in my class, it shows how membranes are structured in a very simple/ cartoonish way.

    Protien channels also play a huge role in your body. Protien channels are trans-membrane proteins found in the phospholipid bilayer membranes in our bodies. These channel proteins allow specific molecules to pass through, crossing the membrane. When you want to move your finger, the protein channels send a message to your brain and nerves to move that finger. The same with any other thing that you move in your body.

                                                                   Diffusion and Osmosis Lab
       We did a diffusion and osmosis lab in our class. In this lab we had a solution of glucose and starch and placed it inside a bag of dialysis tubing. In a cup  outside of the tube, we had water and iodine mixed together. Then we put the tube of glucose and starch mixture inside of the cup with iodine and water, but first tied off the ends tight to make sure they wouldn't mix. After about 30 minutes passed we checked the glucose level of the water in the cup and it came out negative. Over the weekend we let the membrane tube sit in the cup, and the results were that the fluid inside the membrane tube leaked into the cup with iodine and water. The iodine from outside the dialysis tubing also leaked in, because it urned it a different color from mixing with the starch. When we tested both the liquid in the cup and membrane tube, the both had a high glucose level, that was definitely way positive.

     We decided to do another version of the lab and weigh the substances so we could see what left and went into the dialysis tubing. We did four different cups with the substances and water mixed in the dialysis tubing. The four different substances were Corn syrup, Sodium acetate, Antacid tablets, and Sodium bicarbonate. We weighed them three different times to see the results that would come out. The first time we weighed them, we weighed before we put them in the cup of water and cup one with antacid tablets weighed 13.43g. Cup two with the sodium acetate weighed 13.74g. The third cup with corn syrup weighed 11.93g, and the 4th cup with sodium bicarbonate weighed 11.66 g. An hour later we weighed them again, and the 1st cup weighed14.74g, the 2nd cup weighed 23.09g, the 3rd cup weighed 15.88g, and the 4th cup weighed 12.09g. We also did the same thing the day later. Cup one was 14.23g, the second cup was 16.23g,  the third cup was 8.47g, and the fourth was 11.46g. As you can see when we weighed them the hour later, they were at their highest, because thats the time when the water goes through all the little pores in the dialysis tubing, and water moves very quickly because it doesn't have very big molecules, so that is what made that possible. Over night and part of the next day is when the other substances started coming out slowly, because they have bigger molecules than the water and are more dense, so it takes longer for them to go through the tubing. The sodium acetate collected the most water out of all of them, because the molecules of the acetate went through the pores in the membrane easier than all of the substances. Now that we did the lab again in a different way, we really the saw the diffusion and Osmosis come out in the experiments.

Here is a Graph of the data we found out in our lab: