movement of molecules across a membrane powered by atp is called primary active transport.
movement of molecules across a membrane powered by atp is called primary active transport.
movement of molecules across a membrane powered by atp?
primary active transport
in secondary active transport, also known as "coupled transport" or "cotransport", energy is used to transport molecules across a membrane; however, in contrast to primary active transport, there is no direct coupling of atp; instead it relies upon the electrochemical potential difference created by pumping ions in/out of the cell. permitting one ion or molecule to move down an electrochemical gradient, but possibly against the concentration gradient where it is more concentrated to that where it is less concentrated increases entropy and can serve as a source of energy for metabolism (e.g. in atp synthase). the energy derived from the pumping of protons across a cell membrane is frequently used as the energy source in secondary active transport. in humans, sodium (na) is a commonly co-transported ion across the plasma membrane, whose electrochemical gradient is then used to power the active transport of a second ion or molecule against its gradient. in bacteria and small yeast cells, a commonly cotransported ion is hydrogen. hydrogen pumps are also used to create an electrochemical gradient to carry out processes within cells such as in the electron transport chain, an important function of cellular respiration that happens in the mitochondrion of the cell.
active transport
another membrane adaptation seen in some archaea is tetraether phospholipids. this specific adaptation has been found in "p. fumarii" along with other hyperthermophiles. a tetraether phospholipid is a molecule containing two hydrocarbon tails, each coming from one ester bond and one phosphate molecule. these phospholipids form monolayers instead of the typical bilayers seen in most bacteria and all eukaryotes. therefore, instead two different molecules interacting with each other, only one molecule spans the entire width of the membrane. the monolayer then allows for tighter packing of molecules within the membrane because fewer molecules must fit into membrane, however these large molecules are less able to move within the membrane. this then decreases membrane fluidity, allowing the cell to keep more molecules from crossing the membrane. this is an extremely important adaptation because at such high temperatures, molecules move more quickly than at mesophilic temperatures. by decreasing the membrane fluidity, the cell can decrease movement of the phospholipid molecules, which stops unwanted movement of molecules across the membrane.
unique properties of hyperthermophilic archaea