Biology, Bio 110; October 1, 2014 Observing Membrane Structure and Observing Effects of Chemical stress on Membrane Crystal Eve Lopez, Dr. Barua Madhabi
Keywords: beet root model system, spectrophotometer, betacyanin, cellular membrane, phospholipid
The cellular membrane separates and protects the cell acting almost as a wall. Depending on what stressors there are the cellular membrane can become damaged. The objective of this experiment was to examine the structure of the cell membrane using the beet root model system by observing the effects of solvents on the beet root. The beet root was placed in seven solvents to see if the beetroot would leak any of its color to see if the membrane was damaged and by how much. The color intensity was observed by eye and measured using a spectrophotometer. Of the solvents that had beetroot, .9% saline had a color intensity of .002, 1% acetone had .009, 25% acetone produced an intensity of .119, 50% with the intensity of .647, 1% alcohol had .006, 25% alcohol had .022, and 50% alcohol had .177. The highest concentration of acetone inflicted more damage on the membrane of the beetroot causing it to leak its betacyanin in a higher intensity than any of the other solvents had caused. Acetone and methanol can both cause damage to the membrane of the beetroot but acetone has a greater ability and is more damaging. The beet root model system shows the effects of chemical stress on membranes.
The membrane of the cell contains and separates the cell from the outside and itself. It has four major components. The phospholipid bilayer is one of the main components of the cell membrane; the bilayer forms a membrane that surrounds and protects the cell. Phospholipids themselves are composed of a polar hydrophilic head and non polar hydrophobic tails. Inside the hydrophilic head is a glycerol group and a phosphate group that sometimes can have a choline group or sugars attached to its R group. The hydrophobic tails are two chains of fatty acids with more than 12 carbons. The hydrophobic tails face each other and the hydrophilic head faces outward, forming a bilayer. (Vodopich, pp. 105) (Raven, pp. 8994) Membranes have proteins embedded in the phospholipid bilayer. Transmembrane proteins are another major component of the membrane. They have various functions and carry out several duties that all happen within the phospholipid bilayer. They can help transport solutes in and out of the cell using diffusion or facilitated diffusion. They can be catalytic and using enzymes change a solute in a minimal way. They can also be a cell surface receptor; receiving signals on the surface that physically bond to the receptor and then sends a different signal inside the cell. They also can be a surace identity marker; marking the types of sugars that are at the surface of the cell. They also can adhere to another cell when receiving a protein from the other cell. The last function they have is attachment to the cytoskeleton within the cell at certain points along the bilayer. These proteins are displayed in a fluid mosaic model that shows how these proteins are dispersed about the bilayer in a random fashion.(Vodopich, pp. 105) (Raven, pp. 8994)
The last major components of the membrane are the protein networks and cell surface markers. Network proteins are what the cytoskeleton is made up of. There are three types of cytoskeleton fibers; actin filament, microtubules, and intermediate filaments. Actin filament are thin and wire like and responsible for cellular contractions. Microtubules are hollow and wide and move materials within the cell. Intermediate filaments are thick than actin but thinner than microtubules and are rope like, these are twisted throughout the cell and provides the stability and shape. Each major component plays a role in the structure and function of the cell. (Raven, ...
Cited: Raven, Peter H., Johnson, George B., Losos, Jonathan B., Mason, Kenneth A., Singer,
Susan R. Biology. Boston: McGrawHill Higher Education, 2011. Print.
Vodopich, Darrell S., and Moore Randy. Biology Laboratory Manual. 9th ed. McGraw
Hill Companies, 2011. Print.
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