Process and present data as professionally formatted figures

Process and present data as professionally formatted figures Compare results to Experimental Predictions Analyze and interpret results in light of Theoretical Predictions Propose independent follow-up experiments Background Information A cell does not have everything it needs to grow on its own. It requires some way to let in or bring in some things. Some molecules can freely pass in and out of the cell. A cell also needs to let only certain molecules into or out of the cell, but not every molecule. Our current model in cell biology proposes that the cellular membrane performs these roles. It lets certain things in and out, and blocks the passage of yet other things. What kinds of principles does the cellular membrane operate under to allow only certain substances into or out of a cell? Your task before coming to lab for Lab 1 Part 1 are boxed in bold italics: Predict whether the following molecules can get into or out of a cell, and WHY? H20, Na+, CI-, glucose, sodium aside (see below), Dye NR-2010 (see below), DNA Propose 3 ways that molecules could get into or out of a cell. Notes on materials used in this protocol: Dye NR-2010: formula weight of 278.8 g/mol, and is a green-black crystalline powder. When in solution, Dye NR-2010\'s color changes with pH, from amber in a basic environment (pH tilde 8.0) to red in a solution with an acidic pH. In solution, it has an absorbance spectrum with a peak at 520-530 nm. It can be used to stain cells, so we know that it somehow

Solution

The principle followed by the cell membrane is semipermeability or it acts as a differentially permeable barrier during transport of molecules into or out of the cell. The lipid bilayer model of the cell membrane which has a polar hydrophilic head and two nonpolar hydrophobic tails are mainly responsible for the semipermeability of cell membrane.

H2O moves into the cell by facilitated diffusion through specialized intrinsic protein lined channels called aquaporins. Since lipid bilayer is impermeable to water. Generally water flows in the direction of osmotic gradient. Whether there will be a net movement of water into or out of the cell depends on whether the cell’s environment is isotonic, hypotonic or hypertonic.

Na+ can move into or out of the cell by facilitated diffusion when it moves from high to low concentration region and by active transporters i.e pumps from low to high concentration. As it is a hydrophilic substance.

Cl- also moves by facilitated diffusion through chloride gates. Glucose is transported by GLUT transporters through  facilitated diffusion . large molecules like DNA are not easily transpoted across the cell membrane they require carriers. Sodium azide moves through the cell membrane by passive diffusion.

Depending on the requirement of the cell a substance may go in or out of the cell by active transport, where energy (ATP) is required to facilitate the transport of the molecule across the membrane or by passive diffusion, where energy is not required but in facilitated diffusion channels or gates and carrier proteins are required for transport from high to low concentration.