Flashcards in Transport Deck (24)
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1
The cytoplasmic membrane has a ___ that prevents leakage and functions as a ___ for nutrient transport in and out
permeability barrier/gateway
2
Why does water transport freely across the membrane?
it is small and weakly polar
3
___ PRO transport those molecules that the membrane isn't permeable to
integral
4
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
5
Describe active transport
transports solutes against a gradient
6
Transport systems are ___; the rate of update becomes ___ and increase of substrate ___ increase rate
saturable/maximal/doesn't
7
Transport systems are ___; they transport ___ molecules or molecules ___
specific/single/of a series
8
True or false: biosynthesis is not very regulated by the cell
false, it is highly regulated
9
In unicellular organisms nutrients are usually acquired via ___, in multicellular they're usually acquired via ___ or ___
active transport/diffusion/facilitated diffusion
10
What are the types of facilitated diffusion? Include a brief description
1. channel-mediated: specificity is low, can be closed by cell (gated)
2. 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
11
Types of transporters: ___ (one molecule), ___ (one in, another out), ___ (two in the same direction)
uniporter/antiporter/symporter
12
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
13
What are some pmf transporters that use H+ gradient?
cation uniporter, proton symporter, anion symporter, proton-X symporter
14
What are some pmf transporters that use Na+ gradient?
Na-anion symporter, Na-X symporter
15
Where is the Na+ generated pmf common?
marine environments
16
What are the three components of ABS transporters?
1. membrane-spanning PRO (active transport carrier)
2. ATP-hydrolyzing PRO (provides energy for active transport)
3. substrate-specific binding PRO (has high affinity for specific substrate)
17
How do ABC transporters function?
binding PRO binds to substrate and transfers it to the transporter where it is actively transported using ATP generated
18
Where is the binding PRO (for ABC transporter) in G+ and G- organisms?
G+: anchored in the cytoplasmic membrane
G-: free in periplasm
19
What are the rates of permeability of glucose and glycerol?
glucose: 0.001 (fair/poor)
glycerol: 0.1 (good)
20
Describe group translocation?
substrate is modified as it passes through transporter across the membrane
21
What is an example of group translocation?
PEP-dependant sugar phosphotransferase system, used by bacteria to transport common monosaccharides
22
How is transport done in unicellular eukaryotes?
pmf is generated inside the mitochondria usually but in this case it needs to be generated in the cytoplasmic membrane; proton translocating ATPase in the cytoplasmic membrane used ATP to pump out protons which generates a pmf at cytoplasmic membrane level which is used to power symporters in the cytoplasmic membrane
23
How many H+ do F-type ATPase and P-type ATPase pump out during generating of the cytoplasmic membrane pmf?
F: 3
P: 1
24
