16 Questions
What is the primary function of the phospholipid bilayer in terms of communication?
To control the flow of information between cells and the environment
What is the percentage of lipids in a cell membrane?
40%
What is the primary role of carbohydrates in membrane composition?
To facilitate cell recognition
What is the function of integral proteins in the cell membrane?
To facilitate transport of molecules across the membrane
What is the result of van der Waals forces in the lipid bilayer?
Stability of the bilayer formation
What is the function of peripheral proteins in the cell membrane?
To modify the activity of integral proteins
What is the primary function of the mitochondrial membrane?
To conserve energy through oxidative phosphorylation
What is the lipid mosaic model?
A model that describes the structure of the lipid bilayer
What is the primary function of cholesterol in maintaining cell membrane fluidity?
To prevent excessive separation or tight packing of phospholipids
What is the shape of an erythrocyte membrane?
Biconcave disc
What type of bonds are present in unsaturated fatty acid chains?
Double bonds
What is the primary function of Band 3 in the erythrocyte membrane?
To facilitate the exchange of Cl- and HCO3-
What is the role of ankyrin in the erythrocyte membrane?
To link integral membrane proteins to the spectrin-actin cytoskeleton
What is the effect of cold temperature on phospholipids in the cell membrane?
They come closer together
What is the function of spectrin in the erythrocyte membrane?
To crosslink with actin
What is the effect of saturated fatty acid chains on cell membrane fluidity?
They decrease fluidity
Study Notes
Membrane Permeability and ATP-Dependant Pumps
Phospholipid Bilayer Function
- Controls the flow of information between cells and the environment
- Recognition of signaling molecules
- Selective control of substance transport
Mitochondrial Membrane
- Involved in energy conservation through oxidative phosphorylation
Membrane Composition
- Phospholipids: amphipathic molecules with a glycerol backbone, two hydrophobic fatty acid chains, and a phosphate hydrophilic head group
- Fatty acids are poorly soluble in water
- Composition: 40% lipid, 60% protein, 1-10% carbohydrate
Lipid Mosaic Model
- Van der Walls forces allow bilayer formation between hydrophobic tails, providing stability
- Lipid bilayers have low permeability to ions and polar molecules
Membrane Proteins
- Integral proteins: embedded within the phospholipid bilayer
- Peripheral proteins: attached to the surface of the phospholipid bilayer
Carbohydrates in Membrane Composition
- Attached to lipids and proteins on the exterior surface of the cell
- Allow for cell recognition
- Form glycoproteins (membrane proteins with a carbohydrate group) and glycolipids (modified lipids with a carbohydrate group)
Glycocalyx
- Highly hydrophilic
Cell Membrane Fluidity
- Influenced by three factors:
- Temperature: cold temperatures cause phospholipids to be closer together, while hot temperatures cause them to move farther apart
- Cholesterol: prevents excessive separation or tight packing of phospholipids, maintaining fluidity
- Saturated and unsaturated fatty acids: saturated fatty acids have straight chains and pack tightly, while unsaturated fatty acids have kinks in their chains, making them harder to pack tightly
Erythrocyte Membrane Model
- Biconcave disc shape with a 120-day lifespan
- Specialized cytoskeleton (spectrin and actin) provides flexibility and stability
- Composed of lipids and proteins
Band 3, Ankyrin, Protein 4.2, and Spectrin
- Band 3: a Cl-/HCO3- exchanger and integral protein that links to protein 4.2 and ankyrin
- Ankyrin: a protein that links integral membrane proteins to the spectrin-actin cytoskeleton
- Protein 4.2: an ATP-binding protein that may regulate the association of band 3 with ankyrin
- Spectrin: a protein that crosslinks with actin
Learn about the function of phospholipid bilayer, ATP-dependent pumps, and transporters in membrane permeability, including communication, reception, and selectivity.
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