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Essay on plasma membrane
Plasma membrane essays
Essay on plasma membrane
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Transport Across Plasma Membrane
The plasma membrane covers all living cells, enabling the cells’
contents to be held together and controls movement of substances into
and out of the cell.
Plasma membranes are made of phospholipids, proteins and
carbohydrates. The phospholipids are essentially made out of two fatty
acid chains and a phosphate-glycerol group. They are arranged in a
bilayer with the hydrophilic phosphate head facing outwards and the
hydrophobic fatty acid chains facing inwards and to each other in the
middle of the bilayer. This effectively provides a barrier to all but
the smallest molecules.
In the membrane are proteins that have a number of functions. Those
that span across the entire bilayer (from hydrophobic head to
hydrophobic head) act as channels and carriers to transport substances
across the membrane in active or facilitated diffusion. Those on the
surface act as receptors with specific binding sites where hormones
and other chemicals can bind. This binding in turn triggers other
events in the cell.
Finally, those that are on the inside surface maintains the cell’s
shape and motility, such as enzymes.
Glycoprotiens and glycolipds are found on the surface of the cell.
They form a cell coat (glycocalyx) and are important in cell
protection and recognition.
The bilayer is described as fluid since the lipids within it are able
to slide around and exchange places with each other freely. This
feature allows processes such as phagocytosis to occur.
There are five main ways in which transport across cells can occur:
Simple Diffusion;
The only substances that can diffuse directly th...
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...ules gets near the cell, the membrane forms a slight dip or pit.
When they are close enough, they are enclosed by a fold of the
membrane, which then pinches shut to form a closed vesicle. As the
vesicle moves into the cell, the molecules are digested and the
product molecules released. When the materials are small and often
liquid particles, endocytosis is known as pinocytosis. When the
materials are large and often solid particles, the process is known as
phagocytosis.
Exocytosis is the transport of materials out of a cell. It is the
exact reverse of endocytosis. The molecules to be transported have to
be enclosed in a membrane vesicle first, usually from the Golgi
apparatus and RER. It then moves to the membrane and fuses with it,
forcing the substances out.
These processes are controlled and require energy.
Margination and adhesion to the endothelium, in which accumulation of leukocytes occurs along the endothelial wall for adhesion. Afterward, these adhesions cause the separation of endothelial cells, allowing the leukocytes to extend and Transmigrate through the vessel walls. Followed by the response of chemical mediators(chemotaxis) that influence cell migration via an energy directed process which triggers the activation of Phagocytosis, in which monocytes, neutrophils, and tissue macrophages are activated to engulf and degrade cellular debris and
Cell Membrane-Sonar. Sonar on a submarine is the cell membrane in the cell. The cell membrane completely surrounds the cell protecting it’s contents from the surrounding environment.The cell way is a bilayer like sandwich with hydrophilic phosphates on either end surrounding a layer of lipids. Through diffusion and or active transport material comes in and out of the cell. Inside of the membrane pieces of the cell can move around and and change their position relative to the entire cell. On a s...
Investigating the Effect of Concentration on the Rate of Diffusion Aim: To find out if concentration affects the rate of diffusion. Prediction: I predict that the higher the concentration of acid the faster the reaction will be. Hypothesis: Diffusion is the spreading out of a gas or liquid from an area of low concentration to another area where it has a lower concentration until the overall concentrations are balanced. The Hydrochloric acid (HCl) diffuses into the gelatine cube of which contains Sodium Hydroxide (NaOH), which is an alkali. When the Hydrochloric acid combines with the Sodium Hydroxide they form salt and water, which is neutral therefore turning the pink cube to clear.
This cell membrane plays an important part in Diffusion. Cell membrane and Diffusion Diffusion is the movement of the molecules of gas or liquids from a higher concentrated region to a lower concentration through the partially permeable cell membrane along a concentraion gradient. This explanation is in the diagram shown below: [IMAGE] Turgor When a plant cell is placed in a dilute solution or a less concentrated solution then the water particles pass through the partially permeable membrane and fill the cell up with water. The cell then becomes Turgor or hard. An example of this is a strong well-watered plant.
All of these substances cross the membrane in a variety of ways. From diffusion and osmosis, to active transport the traffic through the cell membrane is regulated. Diffusion is the movement of molecules form one area of higher concentration to an area of lower concentration. Concentration gradient causes the molecules to move from higher concentration to a lower concentration.
* We would have to leave one end open to fill it up with the different
Osmosis is the facilitated diffusion of water across the cell membrane of a cell. The inside layer of the cell membrane is hydrophilic, meaning water cannot easily pass through the membrane. The cell membrane has to have aquaporins, which are water channel proteins, that move the water across the membrane. If there is a water and salt solution outside the cell, the salt can enter the cell by diffusion, but the cell membrane is not permeable to the water. Because there is more solute solution inside the cell, there is less water. The aquaporins move the water across the membrane until equilibrium is reached.
In life, it is critical to understand what substances can permeate the cell membrane. This is important because the substances that are able to permeate the cell membrane can be necessary for the cell to function. Likewise, it is important to have a semi-permeable membrane in the cell due to the fact that it can help guard against harmful items that want to enter the cell. In addition, it is critical to understand how water moves through the cell through osmosis because if solute concentration is unregulated, net osmosis can occur outside or inside the cell, causing issues such as plasmolysis and cytolysis. The plasma membrane of a cell can be modeled various ways, but dialysis tubing is especially helpful to model what substances will diffuse or be transported out of a cell membrane. The experiment seeks to expose what substances would be permeable to the cell membrane through the use of dialysis tubing, starch, glucose, salt, and various solute indicators. However, before analyzing which of the solutes (starch, glucose, and salt) is likely to pass through the membrane, it is critical to understand how the dialysis tubing compares to the cell membrane.
An example of simple diffusion is osmosis. Facilitated diffusion on the other hand is dependant on carrier proteins to transport it across the membrane. Diffusion is essential for many organisms as it is a feature of a number of processes which control and supply vital substances to the body in order for basic survival. A few of these are discussed below. Gas exchange is one of these processes.
The Functions of Osmosis Osmosis is the passive transport of water through a selectively permeable membrane, a membrane that allows certain needed particles to pass through it more easily than others. Pores in this type of membrane are large enough for water to pass effortlessly through it. The flow of water during osmosis depends on the concentration of a solute either within a cell membrane or surrounding the membrane. Water naturally flows from a hypertonic solution, an area of high concentration of solute, to a hypotonic district, a solution containing a lower concentration of solute.
Most cell membranes are like that, being permeable to water and some solutes only. Osmosis is therefore the diffusion of water through a partially permeable membrane. The basic principles of diffusion apply here.
The circulatory system is consisted of a group of organs that transfer blood throughout the body and is responsible for the flow of nutrients, oxygen, and other gases to and from all cells. It is also known as the body’s transport system. The system contains three essential components that make up the circulatory system: the heart, blood vessels, and blood. These elements are vital to the body for survival. It includes the pulmonary and systemic circulatory loop. Also, it contains these three independent systems that work together; the heart (cardiovascular), the lungs (pulmonary), arteries, veins, coronary and portal vessels (systemic).
There are many functions lipids have. One of the main functions lipids are structural components in the cell. Lipids make up approximately 50% of the mass of most cell membranes. The lipids that are found in the cell membrane are called phospholipid. Phospholipid are the predominant lipids of cell membrane. Phospholipids aggregate or self-assemble when mixed with water, but in a different manner than the soaps and detergents. Because of the two pendant alkyl chains in phospholipids and the unusual mixed charges in their head groups, micelle formation is unfavorable relative to a bilayer structure.
membranes and are also a component of energy depositing molecules like the ATP and ADP.
Plasma membrane is made up of two layers of phospholipids which are a class of lipids and has many proteins embedded in it. The proteins have a function of providing support and shape to a cell. There are three different proteins in cell membranes (see appendix 1). The plasma membrane also regulates the entry and exit of the cell, as many molecules cross the cell membrane by osmosis and Prokaryotes include several kinds of microorganisms, such as bacteria and cyanobacteria. Eukaryotes include microorganisms as fungi, protozoa, and simple algae.