Microbiology Lecture 6 – Flashcards
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Unlock answersPassive Transport |
transport of a substance across a cell membrane by diffusion, uses gradient energy transports with gradient(cannot use to concentrate nutrients) |
| Active Transport |
The movement of ions or molecules across a cell membrane into a region of higher concentration, assisted by enzymes and requiring energy uses PMF or ATP for energy |
| Primary Active Transport |
| also called direct active transport, directly uses energy to transport molecules across a membrane |
| ABC ATPase |
transporters use ATP in addition to a signal from a periplasmic binding protein to open a transport channel and import a solute.
provides a cap that prevents backflow |
Secondary active transport |
| In secondary active transport, in contrast to primary active transport, there is no direct coupling of ATP; instead, the electrochemical potential difference created by pumping ions out of the cell is used |
| MFS transporters |
are single-polypeptide secondary carriers capable only of transporting small solutes in response to chemiosmotic ion gradients
proteins use energy from gradient of one ion (H+) to move another ion or uncharged solute against its gradient |
uniport |
uses electrical potential (negative inside) like a magnet to pull (+) charged ions into the cell or (-) out A channel protein that transfers only one substrate at a time across the. |
symport |
| a mechanism of transporting two compounds simultaneously across a cell membrane in the same direction, one compound being transported down a concentration gradient, the other against a gradient |
antiport |
|
rocker-switch mechanism |
how gated channels open and close when something moves across the membrane a gate closes behind it to ensure it will not escape. |
Phosphotransferase system |
is a distinct method used by bacteria for sugar uptake where the source of energy is from phosphoenolpyruvate (PEP)
uses a phosphate “relay” to transport glucose |
Type I secretory system |
can cross both membranes in one step |
Drug efflux pump |
| Example of Type I transporter that uses the PMF rather than ATP to power transport |
Type III secretory system |
can cross both membranes in one step |
needle complex |
part in type III secretory system
Transport is blocked until the needle complex contacts a target cell. |
syringe secretion |
in type III secretory systems
protein is secreted DIRECTLY into host (like a syringe) |
| Type II secretory system |
can have a periplasmic intermediate
requires a signal sequence
depend on the Sec or Tat system for initial transport into the periplasm. Once there, they pass through the outer membrane via a multimeric (12-14 subunits) complex of pore forming secretin proteins |
| Chaperone |
| part of Type II secretory system |
| signal sequence |
| part of type II secretory system |
| sec translocon |
| part of type II secretory system |
| TAT secretory system |
| can cross the inner membrane fully folded |
