Plasma Membrane and Diffusion - Case Study Example

Plasma Membrane and DiffusionIntroductionThe interior of the cells is separated from the outside by a membrane known as a cell membrane whose permeability to ions and organic molecules are selective[Yos07]. The cell membrane controls the move movement of molecular particles in and out of the cell and its main function is protecting the cell from its surrounding. The cell membrane is mainly composed of the lipid layer embedded with proteins and it’s involved in the following cellular processes: Signaling of the cell, Adhesioning of the cell and conductivity of the ions in the cell and it forms the external attachment of cells interior to the extracellular structures which include: The cell wall, glycocalyx and intracellular cytoskeleton[Yos07].

The plasma membrane which is also known as the cell membrane borders the cytoplasm of cells and has a cell wall which provides support to the cell and prevents the passage of larger molecules into the cell and it anchors the cytoplasm providing the cell with a shape. The plasma membrane attaches itself on other cells and the extracellular matrix and this helps group cells together to form tissues [Dan11].The plasma membrane’s selective permeability enables it to regulate movement or transport of materials in and out of the cell hence it facilitating the transport of materials needed for survival.

DiscussionThe process of movement of substances across the cell membrane is either active or passive. Passive transport does not involve input of any cellular energy while active transport requires the cell to dissipate energy so that it can take place [Yos07]. The cell membrane is structured such that it allows only specific things to pass through it hence making it a selective permeable plasma membrane. Diffusion is a means of active transport which results from thermal, random movement of molecular particles from regions of high concentrations to regions of low concentrations[Reg10].

There are six factors which influence diffusions in fluids, these includes: Concentration gradient, size of the molecules involved, Distance travelled by the molecules, Temperature of the medium and the molecules, Solubility of the molecule and the surface area of the plasma membrane in which the molecule can carry out its activities, Hence the rate of diffusion is given by the ratio of the product of solubility, gradient, temperature, surface and the product of distance the molecules moves by the square root of the mass of the molecule.

Diffusion can be classified into three categories or types, which include; simple diffusion, channel diffusion and facilitated diffusion[Reg10].Simple diffusion occurs when micro or small non-polar molecular particles goes through a fluid (liquid or gases) mostly liquids through a lipid bilayer. This diffusion type is characterized by hydrophobic molecules moving to hydrophobic regions without being rejected[Reg10]. Hydrophilic molecules do not participate in simple diffusion because they would be rejected when they move into the hydrophobic region of the membrane.

Channel diffusion is a type of passive transport which involves channel proteins in which the molecule move through an open, aqueous pore and it can be regulated. Charged particles and ions can pass through the pore [Yos07].Facilitated diffusion as a type of passive transport that depends solely on protein carriers that is: molecules moves along with the carrier.ConclusionThe plasma membrane makes use of transport mechanisms that involve biological membranes which include: Passive diffusion, Trans membrane protein channels, Endocytosis and exocytosis.

Passive diffusion involves the movement of some small molecule ions such water, oxygen and carbon dioxide through the plasma membrane by diffusion, other ions and molecules which do not pass through the cell membrane by diffusion do so by osmosis.Trans - membrane protein channels enables the movement of nutrients (amino acids and sugars) and water to enter into the cell and other metabolism products out of the cell through the cell membrane[Dan11]. This involves the pumping of these molecules across the plasma membrane through protein channels which are quite specific.

In Endocytosis, the cells absorb molecules by engulfing them, and then the plasma membrane forms deformation inward where the particle to be transported is captured[Dan11].In exocytosis, materials are brought to the cell by invagination and the formation of a vesicle where the vesicle membrane has fused with the cell wall also known as plasma membrane. [Reg10].Works CitedYos07: , (1), Dan11: , (2), Reg10: , (3), Dan11: , (2),