Transport Flashcards
The cytoplasmic membrane has a ___ that prevents leakage and functions as a ___ for nutrient transport in and out
permeability barrier/gateway
Why does water transport freely across the membrane?
it is small and weakly polar
___ PRO transport those molecules that the membrane isn’t permeable to
integral
Describe facilitated diffusion
transports solutes down a gradient, for uncharged substrates the gradient alone determines the direction but for charged particles the charge and gradient have an effect
Describe active transport
transports solutes against a gradient
Transport systems are ___; the rate of update becomes ___ and increase of substrate ___ increase rate
saturable/maximal/doesn’t
Transport systems are ___; they transport ___ molecules or molecules ___
specific/single/of a series
True or false: biosynthesis is not very regulated by the cell
false, it is highly regulated
In unicellular organisms nutrients are usually acquired via ___, in multicellular they’re usually acquired via ___ or ___
active transport/diffusion/facilitated diffusion
What are the types of facilitated diffusion? Include a brief description
- channel-mediated: specificity is low, can be closed by cell (gated)
- carrier-mediated: substrate binds to one side of the membrane and induces a conformational change, the substrate is then released on the other side, much more specific and required no energy
Types of transporters: ___ (one molecule), ___ (one in, another out), ___ (two in the same direction)
uniporter/antiporter/symporter
Describe pmf-dependant transport
in bacteria and archaea, under conditions where respiration is possible a pmf is generated, if respiration is not possible ATPases can create a pmf, some sym and antiporters can use the pmf to generate energy
What are some pmf transporters that use H+ gradient?
cation uniporter, proton symporter, anion symporter, proton-X symporter
What are some pmf transporters that use Na+ gradient?
Na-anion symporter, Na-X symporter
Where is the Na+ generated pmf common?
marine environments