structure and function of plasma membrane in cells

The plasma membranes are made up of proteins that form pores and channels, cholesterol to provide membrane stability and carbohydrate molecules for cell recognition. The most abundant component found in the plasma membrane is the phospholipid, which is bilayer. The plasma membrane is amphipathic

Membranes contain phospholipid bilayer these are two layers of phospholipids which are facing in opposite directions to each other. The non-polar tails are hydrophobic which are water-hating, what makes it difficult for polar molecules/ions to pass through them are the fatty acid tails which also act as a barrier to water-soluble substances. These molecules move in and out of the cell by diffusion, osmosis and active transport. Diffusion is the net movement of particles down a concentration gradient for example when gases move about and will move from where there is a high concentration to where they are in lower concentration. By osmosis, the diffusion of water through the plasma membrane is possible because the lipids bilayers are water-resistant to important molecules and small molecules like oxygen and carbon dioxide, these molecules and ions diffuse freely across the cell membrane. By active transport, ions and molecules are forced using metabolic energy to move against their concentrated gradient.

Diffusion is defined as the movement of molecules from an area of high concentration to an area of low concentration. The diffusion of water molecules through a semi-permeable(selectively permeable) membrane is osmosis. Semi-permeable means that some molecules can move through the membrane while others can not. Diffusion and Osmosis are passive forms of transport requiring no energy. Active Transport utilizes energy in the form of ATP. Water is a solvent that can dissolve a number of substances more than any other substance. Wherever water goes, through the ground or a body, it takes along valuable molecules. Water’s chemical composition causes it to be attracted to many different molecules and be attracted so strongly it disrupts the forces and dissolves it. Water can pass through the semipermeable membrane without any help but can change the solution, on the other side of the cell membrane, depending on how much it diffuses in and out.

Materials move into and out of cells through either passive transport or active transport. Passive transport includes diffusion and osmosis. Molecules tend to move from crowded to less crowded in order to achieve a balance or to reach homeostasis. The cell membrane is selectively permeable which allows the movement of substances, especially oxygen, water, food molecules, carbon dioxide, and waste products, into or out of the cell without the use of energy. Movement occurs when there are unequal concentrations of a substance inside and outside of the cell.

Osmosis and diffusion are passive transport mechanisms, meaning that no energy has to be added into the system in order for transport to occur, which the cell uses in its selectively permeable membrane. Osmosis involves the transportation, or movement, of water from an area of low solute concentration to an area of higher solute concentration. Diffusion is the movement of solute particles from areas of high solute concentrations to areas of lower concentrations of solutes. Therefore, both osmosis and diffusion work on a concentration

Some molecules can pass into the cell by facilitated diffusion. This is passive due to the nature of diffusion and because the solute is moving down its

Water diffuses across the membrane from the region of lower solute concentration (higher free water concentration) to that of higher solute concentration (lower free water concentration) until the solute concentrations on both sides of the membrane are equal. The diffusion of free water across a selectively permeable membrane, whether artificial or cellular, is called osmosis. The movement of water across cell membranes and the balance of water between the cell and its environment are crucial to organisms. ("Diffusion And Osmosis - Difference And Comparison | Diffen"). A semi-permeable membrane known as the cell membrane surrounds the living cells of both plants and animals. Both solute concentration and membrane permeability are taken into account in the ability of a cell to gain or lose water. If there is a higher concentration of solutes in the surrounding solution, water will tend to leave the cell, and vice versa. The membrane forms a selective barrier between the cell and its environment and does not allow toxic substances from the surroundings to enter into the cell (Deena T Kochunni). The selective permeability allows the cell to regulate the flow of necessary substances into and out of the cell. In plants osmosis is also responsible for absorbing water and minerals from the soil by using the semipermeable membrane of the root (Deena T Kochunni). If the extracellular fluid has a lower osmolarity than the fluid inside the cell, it’s said to be

Activity 3: Osmosis Osmosis is a specific type of diffusion. It is the movement of water molecules from an area of high water concentration to an area of low water concentration. Semipermeable membranes, such as the cell membrane, allow the unrestricted movement of water across the membrane, at the same time restricting the movement of solute molecules and ions. It has been estimated that an amount of water roughly equivalent to 250 times the volume of the cell diffuses across the red blood cell membrane every second. Despite this large movement of water molecules, the cell does not lose or gain water, because equal amounts go in and out.

Cell membrane is a selective boundary composed of a unique phospholipid bi-layer structure consisting of lipids, proteins and carbohydrates. This structure regulates the import and export to maintain homeostasis condition inside the cell. (Knox et al., 2014) The plasma membrane is referred as a fluid mosaic which also has selective permeability. The permeability of the membrane can be varied depending on the external conditions. (Mitchel, 2015)

There are two main types of membrane transport proteins: firstly, there are channel proteins, which are essentially pores that extend across the membrane. These pores create a hydrophilic passage for molecules through he hydrophobic bilayer. The rate of movement through these pores is significantly faster

1. Osmosis, Active transport, and Facilitated diffusion Osmosis: 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.

The sodium potassium pump is a type of active transport because it uses ATP as energy to change the shape of the channel. Co-transport with glucose is a type of active transport but could not be possible without the indirect help of ATP to pump Na+ ions out to make higher concentration gradient outside of the cell, so ATP is indirectly involved in co-transport. Protein channels are a type of passive transport because they use facilitated diffusion to pass into cellular membrane which is the process of a molecule usually a sugar or amino acid is placed on a binding site of that protein which makes the protein change shape or open its channeling, which allows the molecule to enter the cell otherwise facilitating the process, no ATP is involved in this process.

All cells contain membranes that are selectively permeable, allowing certain things to pass into and leave out of the cell. The process in which molecules of a substance move from an area of high concentration to areas of low concentration is called Diffusion. Whereas Osmosis is the process in which water crosses membranes from regions of high water concentration to areas with low water concentration. While molecules in diffusion move down a concentration gradient, molecules during osmosis both move down a concentration gradient as well as across it. Both diffusion, and osmosis are types of passive transport, which do not require help.

The ability of water to move across cell membranes is important to living things. Water moves across cell membranes through various processes such as osmosis, diffusion, and active transport. These processes enable the transfer of ions in plants and aids the vascular system in animals. These procsses are key to the survival of organisms.

Plasma membrane is a border that covers all cells. This coating is difficult, due to the parts always moving allowing specific materials into the cell and keeping substances away. Phospholipid bilayer is what plasma membrane is made of, and they are membrane proteins. “Because it is made of different pieces that form a pattern and seem to float and move in watery environments” (Daempfle, 2016) the plasma membrane is called the fluid mosaic. The fluid mosaic model consists of several macromolecules. Integral proteins spread the whole lipid bilayer; peripheral proteins which sits either inside or outside of the membrane. These two macromolecules serve as foundation cells to one another to transport materials across the membrane, take in chemicals,