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22 Cards in this Set
- Front
- Back
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posttranslational localization
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proteins are released into the cytosol after synthesis and then associate with the organelle.
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cotranslational localization
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for the E.R., proteins are transfered into a recepter complex on the ER membrane during translation.
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how is the shape of a eukaryotic cell determined?
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by its cytoskeleton
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What incorporates the cytoskeleton?
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internal framework of filaments, including microtubules, actin filaments and intermediate filaments.
-also provides an organizing template for many activities, including anchoring organelles in place. |
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signal transduction
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events on the outside of the cell can trigger actions inside the cell by using receptor proteins embedded in the membrane.
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cell membranes define?
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compartments/organelles of different functions and compositions.
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How do most solutes pass the cell membrane?
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They pass through by transport proteins.
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membrane spanning transport proteins
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catalyze transport of ions and hydrophilic molecules across the membrane.
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What are the two principal types of membrane transport proteins?
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cannels and carriers
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ion channels
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allow transport of ions across a membrane, down their electrochemical gradients. They for a continuous pore though which ions can flow.
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What are the characteristics of ion channels?
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-solute selectivity
-rapid rate of solute passage -regulation by some kind of gating mechanism. |
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passive transport
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ion flow though channels
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carrier proteins
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use energy of the electrochemical gradient or ATP ir light to transport solutes.
-they alternate between different solute bound conformations to move solutes and can move solutes against their concentration gradient. -the conformational changes are required for each ion or molecule transported. |
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pumps
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are carrier proteins that use ATP or light energy to transport solutes against their electrochemical gradient.--> primary active transport
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membrane potential
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a difference in charge across a membrane.
-generated by an electrochemical gradient across a membrane that is selectively permeable to ions. |
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transporters
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are carrier proteins that use the energy of the elctrochemical gradient to transport solutes--> secondary transport
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electrochemical gradient
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is the concentration gradient PLUS additive/subtractive effects of electrical gradient.
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what is the nernst equation used for?
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to calculate the membrane potential as a function of ion concentrations.
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what is a membrane potential a prerequisite for?
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for electrical signals and for directed ion movement across cellular membranes.
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what are the types of carrier proteins?
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-pumps, transporters
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what are the types of transporters?
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-uniporter -->one molecule
-symporter--> two solutes same way -antiporter--two solutes different directions |
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gating
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the ability of a channel to open and close in response to a stimulus. (ligand, voltage, etc).
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