There are two major ways molecules can be transported across cells. This can be either Passive or Active and while active requires the use of energy, passive does not. Passive transport requires the movement of particles from high to low concentration such as diffusion and osmosis, active transport in contrast requires the movement of particles from low to high concentration hence why energy is needed.
Diffusion: The movement of particles down a concentration gradient from an area of high concentration to an area of low concentration until evenly distributed. A solution is required which includes a solute + solvent. Water is a universal solvent and sugar or salt is a good example of a solute.
Osmosis: This is the movement of water particles in a solution from an area of high concentration to an area of low concentration across a selectively permeable membrane. A selectively permeable membrane or partially permeable membrane only allows certain molecules or ions to cross it. It can be described as a sieve or filter.
Active Transport: Movement of molecules or ions across a cell membrane from a region of lower concentration to a region of higher concentration against the concentration gradient. This process is most seen in the sodium-potassium pump (Na+/K+ ATPase) that helps to create a resting potential in the cell using ATP.
An example of osmosis in living things, (plants) is the uptake of water from the soil by root hairs.
ReplyDelete2 reasons why Transport processes are Important to living organisms are 1) Transport processes help in the growth and respiration of the cells and 2) Transport processes take away waste products to the excretory organs for elimination from organisms bodies
ReplyDeleteDiffusion occurs in our lungs. When we take in oxegen it is highly concentrated in our lungs and our blood cells move the oxegen around our body to evenly distrubute it to our organs and other cells.
ReplyDeleteOne example of osmosis in human beings is the process by which our kidneys filter waste products from our blood. The kidneys contain millions of tiny filtering units called nephrons. Each nephron contains a semipermeable membrane that allows water and small molecules to pass through, but blocks larger molecules such as proteins.
ReplyDeleteAs blood flows through the nephron, water and other small molecules are filtered out of the blood and into the nephron tubule. These molecules then pass through the semipermeable membrane of the tubule and into the surrounding fluid, which has a higher concentration of solutes.
This causes osmosis to occur, with water moving from the tubule back into the surrounding fluid to balance out the solute concentration.
Osmosis is how plants are able to absorb water from soil. The roots of the plant have a higher solute concentration than the surrounding soil, so water flows into the roots. In plants, guard cells are also affected by osmosis.
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