facilitated diffusion occurs within the plasma membrane in the cell membrane.
facilitated diffusion occurs within the plasma membrane in the cell membrane.
where does facilitated diffusion occur in the cell membrane?
within the plasma membrane
non-polar molecules, such as retinol or lipids, are poorly soluble in water. they are transported through aqueous compartments of cells or through extracellular space by water-soluble carriers (e.g. retinol binding protein). the metabolites are not altered because no energy is required for facilitated diffusion. only permease changes its shape in order to transport metabolites. the form of transport through a cell membrane in which a metabolite is modified is called group translocation transportation.
facilitated diffusion
in living organisms, the main physical and biochemical processes that are required for survival are regulated by diffusion. facilitated diffusion is one form of diffusion and it is important in several metabolic processes of living cells. one vital role of facilitated diffusion is that it is the main mechanism behind the binding of transcription factors (tfs) to designated target sites on the dna molecule. the in vitro model, which is a very well known method of facilitated diffusion, that takes place outside of a living cell, explains the 3-dimensional pattern of diffusion in the cytosol and the 1-dimensional diffusion along the dna contour. after carrying out extensive research on processes occurring out of the cell, this mechanism was generally accepted but there was a need to verify that this mechanism could take place in vivo or inside of living cells. bauer & metzler (2013) therefore carried out an experiment using a bacterial genome in which they investigated the average time for tf – dna binding to occur. after analyzing the process for the time it takes for tf's to diffuse across the contour and cytoplasm of the bacteria's dna, it was concluded that in vitro and in vivo are similar in that the association and dissociation rates of tf’s to and from the dna are similar in both. also, on the dna contour, the motion is slower and target sites are easy to localize while in the cytoplasm, the motion is faster but the tf's are not sensitive to their targets and so binding is restricted.
facilitated diffusion