1.Discuss the structure of the plasma membrane and explain the process of active and passive transport through the membrane.
2. Explain your observations in detail in terms of concentration gradient, diffusion, osmosis, osmotic pressure, passive transport, and active transport. Explain what happened to the blood cells at the various levels of concentration. Be sure to refer to the solutions as being hypotonic, hypertonic and isotonic.
The plasma membranes are made up of proteins that form pores and channels, cholesterol to provide membrane stability and carbohydrate molecules for cell recognition. The most abundant component found in the plasma membrane is the phospholipid, which is bilayer. The plasma membrane is amphipathic that include both hydrophilic heads and hydrophobic tails. The head is polar and the tail is non-polar. The plasma membrane is what they call a mosaic of lipids, proteins and carbohydrates. Active transport is within the cell membrane which requires the use of energy and moves molecules from low to high concentrations using protein carriers.
The transport are made up of pinocytosis, phagocytes, receptor mediated endocytosis, exocytosis and transcytosis. Pinocytosis is when cells take in tiny droplets of liquid from their surroundings. Phagocytes are white blood cells that take in solid particles such as bacteria and cellular debris, this helps fight off injections or diseases causing microorganisms. The receptor-mediated endocytosis will only let certain particles into the cell, only allowing cells with the appropriate receptors to remove and process its surrounding even in very low concentrations. Exocytosis is a substance that’s placed into a vesicle and comes together with the cell membrane which releases the contents outside of the cell.
The cells secrete proteins this way. Last is the transcytosis which combines both the endocytosis and exocytosis to transport substances from one end of the cell to the other, which is also known as active transport. So over all the active transport is movement of molecules across a membrane that requires energy to be expanded. An example of active transport would be pushing a stroller up a hill. Passive transport is diffusion across a membrane requiring only random motion of molecules with no energy expanded by the cell. Another example of passive transport would be rolling a ball down a hill.
In the rubber egg lab also known as the osmosis lab, I first measured the circumference of the egg which was 6 inches. The egg had no cracks and was hard. I placed the egg in the vinegar and within seconds the egg started to bubble. These bubbles were carbon dioxide. After 72 hours the shell of the egg had started to dissolve or flake. This would be considered passive transport as the vinegar diffused across the egg shell without any force. Seventy-two hours into the experiment the membrane was exposed, and had a circumference of 8 inches. Before the egg had a shell and you couldn’t see through it but once the vinegar acted as an acetic acid it broke down the shell and left a yellow membrane that felt like rubber this is an example of diffusion. I then placed the egg in another container and put corn syrup over the egg for 24 hours. The egg had shriveled and shrunk, the water had left the egg and went into the syrup and that is what caused the egg to shrink.
The corn syrup is essentially pure sugar with very little water so the osmotic pressure is very low. I then placed the shriveled egg in water and waited for another 24 hours. After observation the egg had no wrinkles and had swelled back up. The water had moved through the membrane inside of the egg making the proportions of the molecules equal which caused the egg to swell; this is an example of osmosis. Also when the egg was placed in the water and the egg had expanded was because of the much larger concentration of the water in the in the egg, this would be an example of the concentration gradient. The active transport is against the gradient examples is from the high concentrate to the low concentrate as it requires energy. I removed the egg and decided to try and see if it would bounce or break, I held the egg over my sink about 2 inches up and where it landed the egg split and broke.
In the Ph.I.L.S lab, I placed a red blood cell in hypotonic solution of Na CL, which is very dilute it caused the cell to swell. As an example in the lab I placed a red blood cell in the 50 NaCL solution and the transmittance value was one hundred. When a red blood cell is placed in hypertonic solution of NaCl, which is very concentrated, the cell shrinks because the water had left the cell. The lowest transmittance value was 10 and it was caused when adding 240 Na Cl to the red blood cell. When the red blood cell was placed in isotonic solutions of NaCl water neither leaves nor enter the cell, so it doesn’t swell or shrink. Looking at the data the ranges of NaCl 0-50 the transmittance value stayed the same at one hundred. Also the NaCl ranges of 220-240 stayed the same as well which was 10, this states that it did not shrink nor swell in those ranges.