The flashcards below were created by user
Morgan.liberatore
on FreezingBlue Flashcards.
-
What are transporters used for?
to get nutrients into the cell
-
How does water pass through the membrane?
Water can freely pass the membrane in both directions because it is small and weakly polar
-
What is facilitated diffusion>
Can only transport solutes down a gradient
-
What is active transport?
Can transport sollutes against the electrochemical gradient, uses energy (ATP)
-
If a substrate is uncharged, how is the gradient determined?
By the concentration gradient alone, not the electrochemical gradient
-
What is the main difference between transport and diffusion?
Transporters are saturable, so their rate has an upper limit based on how many transporters are in the membrane
-
How do multicellular organisms acquire nutrients?
In multicellular organisms, nutrients can be acquired by means of diffusion or facilitated diffusion
-
How are nutrients acquired in unicellular organisms, including prokaryotes?
In unicellular organisms, including prokaryotes, nutrients are usually acquired by active transport
-
Are transport systems specific?
Transport systems are highly specidic; a single molecules or a class of closely related molecules
-
How does facilitated diffusion work?
- The binding of the substrate on one side of the membrane induce a conformation change in the carrier in such a way that the carrier open to the other side. The concentration of te substrate is lower there
- The substrates is released and diffuse away from teh carrier
-
What are the 2 types of facilitated diffusion?
-
What are the 2 conformations of carriers?
Open in, or open out
-
What is the difference between carriers and chanels?
Carriers are substrate specific
-
How does active transport work?
When the protein is open to the side with the higher concentration of substrate, a phosphate binds to it and changes the shape, this pushes the substrate out of the protein, and allows something else to bind to it
-
What is a uniporter?
Transports one molecule at a time
-
What is an antiporter?
1 molecule in and 1 molecule out at the same time
-
What is a Symporter?
2 molecules in the same direction at the same time
-
What type of active transport is pmf-dependent?
Simple transport
-
What are the three types of active transporters in prokaryotes?
- Simple transport
- Group translocation
- ABC transport
-
What s simple transport?
Driven by the energy of the proton motive force
-
What is group translocation?
Cjemical modification of the transported substance driven by phosphoenolpyruvate
-
What is ABC transporter?
Periplasmic binding proteins are involved and energy comes from ATP
-
How is Simple transport done when respiration is possible?
ETC pushes protons out, a terminal electron acceptor is present, proton motive force is generated
-
How is simpe transport done when respiration is not possible?
- ATPases can be used to generate the pmt, ATPases work in reverse
- pmf-dependant transporter are smporter or antiporter that use the proton gradient
- Pmf can be used to generate a gradient of Na+ that is used by some transporters as a soure of energy
-
Where is a sodium gradient found and used?
Sodium gradient is apparent in sea water and is used by bacterias in the sea
-
What is an ABC transporter?
- ATP-binding cassette, 3 components:
- A membrane spanning protein, the active transport carrier (not a channel)
- An ATP-hydrolyzing proteins that provide the energy for active transport
- A substrate-specific binding proteins that has very high affinity for a specific substrate (or a class of substrtes)
-
Why is the high affinity important in the ABC transporter?
High affinity allows it to bind in very low concentration
-
Where is the binding protien for ABC transporter found in gram-negative bacteria?
In the periplasm
-
Where is the binding protein for ABC transporter foundin the gram positive bacterias?
Anchored in the cytoplasmic membrane
|
|