Question

LAB REPORT 2: THE CELL: TRANS "ORT 2: THE CELL: TRANSPORT MECHANISMS AND CELL PERMEABILITY Name Class: Date Due Tuesday March 10, 2020: Written in paragraph form & include: Introduction: the purpose of the report Body: Describe the concept of cell permeability. Compare & contrast the various types of cell transport mechanisms that the cell may utilize. Discuss the effects of tonicity on the cell. Conclusion: Discuss the importance of normal cell transport & implications for abnormal mechanisms. c r o N M .

Answer 1

Plasma membrane is the outermost covering present in both prokaryotic and Eukaryotic cell. It is selectively permeable in nature because it allow the movement of only selected molecules across the cell surface. Therefore it acts as a regulator for the movement of molecules. proteins. They are mainly the membrane Transporters which allow the passage of molecules.

Passage of molecules across plasma membrane

Across plasma membrane, molecules can move by two ways, passive transport and active transport.

Passive transport does not require energy and occurs along the concentration gradient. It is of three types, diffusion, osmosis and facilitated diffusion.

Diffusion is the random movement of molecules along their concentration gradient. Small molecules like Oxygen and Carbon dioxide can easily pass through the membrane because of their solubility in the hydrophobic core of the membrane.

Osmosis is the movement of solvent molecules along the concentration gradient. Movement of water through plasma membrane occurs by osmosis.

The amount of solute present in a given cell or solution is called as the tonicity of the cell or solution. The amount of water entering or leaving the cell is dependent upon the relative tonicity of the cell and the medium in which it is present. If the medium is having more amount of solute than the cell, then the medium is hypertonic and in this case water moves from the cell into the medium. This results in the shrinkage of the cell. If the medium is having less amount of solute than the cell, then the medium is hypotonic and in this case water moves inside the cell resulting in swelling. If the medium is having same tonicity as that of cell, then it is said to be isotonic and the amount of water entering and leaving the cell are equal.

Facilitated diffusion is the movement of big size molecules along the concentration gradient with the help of a carrier protein. Carrier proteins are transmembrane proteins embedded inside the membrane. They open and close with response to the movement of molecules. Molecules like glucose are transferred across plasma membrane by facilitated diffusion.

Other type of transport is active transport which requires energy from ATP hydrolysis and Transporters located on the membrane. These Transporters are called Ion channels and pumps. Movement of charged molecules like sodium Ion, potassium ion, hydrogen ion, magnesium iron, calcium ion, chloride ion takes place by active transport.

Fatty acids are important in regulating the flow of molecules. Whenever the plasma membrane has to decrease its fluidity and permeability for the molecules, saturated fatty acids are synthesized and packed into the membrane. This is because these fatty acids pack tightly together and prevent the movement of molecules across plasma membrane.

On the other hand whenever the plasma membrane has to increase its fluidity and permeability for the molecules, unsaturated fatty acids are synthesized and packed into the membrane. This is because these fatty acids do not pack tightly together and allowed the movement of molecules across membrane.

This is the body.

Please rate high.