Term
What is Protein 1?
How mobile is this protein? |
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Definition
Integral Protein
Single alpha helix
Transmembrane protein, not very mobile due to hydrophilicity |
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Term
What is Protein 2?
How mobile is it? |
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Definition
Integral Protein
Multiple alpha helices
Transmembrane protein that is not very mobile due to hydrophilicity. |
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Term
What is protein 3?
How is it's mobility?
What function can it have? |
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Definition
Integral membrane protein
Rolled up Beta sheet (Beta barrel)
Transmembrane protein that can form pores, receptors or enzymes
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Term
What is protein 4?
How is its mobility? |
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Definition
Integral membrane protein
Anchored amphipathic alpha helix
More mobile than the transmembrane proteins due to only interacting with one face of the plasma membrane |
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Term
What is protein 5?
How is it's mobility?
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Definition
Membrane Associated Protein
Anchored by covalently bound lipid chain
More mobile that AA only proteins, the lipid chain moves more freely withing the phospholipid bilayer. |
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Term
What is protein 6?
What is a major function of this type of protein? |
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Definition
Membrane Associated Protein
Oligosaccaride linker
glycosylphosphatodilinositol (GPI) links to a protein after protein is cleaved, leaving the protein on the non-cytosolic surface of the membrane |
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Term
What proteins are 7/8?
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Definition
Peripheral Membrane Proteins
Non-covalent interactions with other proteins
Transiently attached to membrane, they are released by extreme pH and extreme ionic strength |
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Term
| Give examples of restriction of lateral mobility |
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Definition
1. Proteins can assemble into aggregates of lipid rafts
2. Proteins can bind an extracellular structure
3. Proteins can be tethered to cytoskeleton
4. Proteins can interact with proteins on the surface of another cell |
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Term
| Explain the significance of glycosylation and disulfide bonds |
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Definition
Glycosylation occurs in ER lumen and Golgi (sugars are extracellular
On the extracellular side of the membrane, disulfide bonds help maintain protein structure.
Since Cytosol is a reducing environment, disulfide bonds are reduced to sulfihydril groups (-SH)
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Term
| What are the important properties of the cell membrane? |
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Definition
Responsivity
Selective permeability
Fluidity |
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Term
| What are the important functions of the cell membrane? |
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Definition
Signal transduction across membrane by membrane receptors so that membrane may be responsive
Import and export of molecules across the membrane
Membrane must expand and retract in cell movement |
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Term
| Why do phospholipid bilayers and micelles form spontaneously? |
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Definition
Phosphodiacylglycerols are amphipathic, so the polar head will always face water and the non-polar FA tails will act to avoid water |
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Term
What is this?
Describe the charge
Which side of the bilayer are they preferentially on? |
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Definition
Phospholipid
Amphipathic to non-polar tails with a polar glycerol head
They are preferentially located on the cytosolic monolayer and flipped by flipases till membrane is established. |
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Term
What is this?
What is it's function in membrane fluidity? |
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Definition
Cholesterol
Maintains optimal fluidity by providing structure and simultaneously prevents crystallization of phospholipid hydrocarbon chain.
Major component of lipid rafts |
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Term
What is the structure in blue?
What is it's function? |
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Definition
Glycolipids- Are on E-face of membrane to interact with extracellular molecules for a variety of reasons. Added by golgi
Protect against low pH and enzyme degradation
Cell recognition
Provide entry points for some bacterial toxins
Also involved in forming glycocalyx |
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Term
| What properties effect membrane fluidity? |
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Definition
Level of phospholipid tail saturation
Temperature
Level of cholesterol |
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Term
| Describe the structure and function of lipid rafts. |
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Definition
Small region of the plasma membrane enriched in sphingolipids and cholesterol (~70 nm diameter)
Membrane here is thicker due to long straight hydrocarbon chains, ideal for supporting (accumulating) certain proteins
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Term
This picture demonstrates lipid bilayer asymmetry, what is this and which phospholipids are on which side? |
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Definition
All phospholipids are made on the cytosolic side of the ER membrane, therefore, phospholipids that are bound to be on the ECM side must be flipped by flipases. There is no flipase for phosphatidylserine or phosphatidylethanolamine.
EC side phospholipids- sphingomyelin, phosphatidlycholine
Cytosol side phospholipids- phosphatidylserine phosphatidylethanolamine |
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Term
| How does a cell signal apoptosis? |
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Definition
Cell surface phosphatidylserine is signal for macrophages to phagocytose and digest the cell |
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Term
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Definition
Thick coat of sugars on extracellular side provide protection by forming a hydration shell |
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Term
| What forces drive solutes from one side of the membrane to the other? |
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Definition
Concentration Gradient
Electrochemical Gradient |
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Term
| What solutes can passively diffuse through the plasma membrane? |
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Definition
Small uncharged molecules can passively diffuse
Hydrophobic Molecules e.g. O2, N2, CO2, steroid hormones
Small uncharged polar molecules e.g. H2O |
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Term
| Which solutes cannot diffuse through the plasma membrane? |
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Definition
Large uncharged polar molecules e.g. glucose, sucrose
Ions e.g. H+ Na+ etc. |
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Term
What is passive diffusion?
Is a transporter protein required? If so, what type?
Is there an energy requirement, and if so, what is the energy source?
What is the relative rate of solute transport?
What are examples of the types of solutes transported by carriers and channels
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Definition
Channel protein required
No energy requirement
Diffuses 1000x faster than carriers
Examples: Na+ and K+ channels |
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Term
What is passive carrier-mediated transport?
Is a transporter protein required? If so, what type?
Is there an energy requirement, and if so, what is the energy source?
What is the relative rate of solute transport?
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Definition
Yes, Carrier proteins (aka transporters, translocators and permeases)
No energy requirement
Slower than passive diffusion
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Term
What is active carrier-mediated transport?
Is a transporter protein required? If so, what type?
Is there an energy requirement, and if so, what is the energy source?
What is the relative rate of solute transport?
What are examples of the types of solutes transported by carriers and channels
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Definition
Yes, Carrier proteins (aka transporters, translocators and permeases)
Yes, energy aquired from ATP or ion gradient
Diffuses against concentration gradient and slower than passive transports
Na+ K+ pump! |
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Term
What is primary active carrier-mediated transport?
Is a transporter protein required? If so, what type?
Is there an energy requirement, and if so, what is the energy source?
What is the relative rate of solute transport?
What are examples of the types of solutes transported by carriers and channels
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Definition
Yes, carrier proteins
ATP required for energy
Slow
Na+ K+ pump!
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Term
What is secondary active carrier-mediated transport?
Is a transporter protein required? If so, what type?
Is there an energy requirement, and if so, what is the energy source?
What is the relative rate of solute transport?
What are examples of the types of solutes transported by carriers and channels
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Definition
Yes, carrier proteins
Ion gradient used to drive transport
Slow
Na+-taurocholate cotransporting polypeptide (NTCP; in hepatocytes) |
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Term
Differentiate the different types of Channel gating
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Definition
Voltage gated
Ligand gated
Mechanically gated
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Term
| Differentiate the different types of passive carrier-mediated transport |
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Definition
Uniport: The transmembrane movement of a single molecule
Symport: the simultaneous transmembrane movement of two molecules in the same direction
Antiport: the simultaneous transmembrane movement of two molecules in opposite direction |
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Term
| Compare/contrast passive diffusion vs. passive carrier-mediated transport. |
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Definition
| Passive diffusion utilizes channels and is 1000x faster than carrier mediated transport. Passive carrier-mediated transport is slower due to the need to bind to the solute. |
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Term
| Compare/contrast passive carrier-mediated transport vs. active carrier-mediated transport. |
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Definition
| Passive transport does not use energy, active transport does as it goes against a concentration gradient. |
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Term
| Compare/contrast primary active carrier-mediated transport vs. secondary active carrier-mediated transport. |
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Definition
| Primary active transport utilizes ATP while secondary active transport uses and ionic electrochemical gradient to drive transport |
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