Examples of facilitated diffusion are the passing of K+ ions through a membrane with an aid of a potassium transport protein and the passing of glucose and amino acids with the aid of proteins called permeases. Retinol binding protein acts as a water-soluble carrier for retinol and fatty acids.Continue Reading
Diffusion is movement of molecules across a membrane. There are three main types of diffusion: simple, channel and facilitated types. Particles normally move from areas of high concentration to areas of low concentration along the concentration gradient. Prokaryotic cells demonstrate simple diffusion, whereas facilitated diffusion only happens in more complex eukaryotic cells.
Simple diffusion requires no energy and happens linearly. The more particles added to the solution, the higher the concentration becomes. Channel diffusion involves proteins letting molecules through a membrane.
In a facilitated diffusion, an integral protein changes its conformation to let a passing molecule through, as in the case of permeases proteins. Other protein carriers, such as retinol binding proteins, do not change. Carrier or transport proteins stay in their places in the membrane. Transport proteins are tailored to let only particular molecules through.
During facilitated diffusion, unlike other types, individual molecules can travel against the concentration gradient, but the net movement is as in other types of diffusion. As opposed to simple diffusion, saturation can be reached during facilitated diffusion.Learn more about Molecular Biology & DNA
Two examples of active transport include the root hair cells in plants taking in mineral ions and humans taking in glucose through their intestines. In general terms, active transport refers to a substance moving from areas in which it has low concentration to an area with high concentration, and the substance is generally one that a cell needs for sustenance, like amino acids, ions or glucose.Full Answer >
Active transport requires energy because it is pumping particles, such as proteins, ions and sugar molecules, against a concentration gradient: from areas of lower to higher solute concentration. The main energy source for active transport is adenosine triphosphate, or ATP, although electrochemical and light energy are also used.Full Answer >
According to Prentiss Hall, while the epithelial cells of the intestine transport glucose using active transport, the red blood cells use facilitated diffusion across a membrane. The method of active transport required depends on the environment of the cell.Full Answer >
Protease, also known as peptidase or proteinase, is any enzyme that catalyzes the breakdown of proteins into smaller components of peptide fractions and amino acids. This process is known as proteolysis. Proteases are found in all organisms, including animals, plants, viruses and bacteria.Full Answer >