6 Questions
What is the primary function of the cell membrane's selective permeability?
To regulate what enters and leaves the cell
What is the main component of the cell membrane's structure?
Phospholipid bilayer
What type of transport uses energy to move molecules against their concentration gradient?
Active transport
What is the role of cholesterol molecules in the cell membrane?
To increase membrane fluidity and stability
According to the fluid mosaic model, what is the nature of the phospholipid bilayer?
Fluid and dynamic
What type of protein is embedded in the cell membrane and extends across the membrane?
Transmembrane protein
Study Notes
Cell Membrane
Functions:
- Regulates what enters and leaves the cell (selective permeability)
- Provides structural support and maintains cell shape
- Acts as a barrier to separate internal cellular components from external environment
- Allows for cell signaling and communication with other cells
Composition:
- Phospholipid bilayer (double layer of lipids with hydrophilic heads and hydrophobic tails)
- Embedded proteins (transmembrane, peripheral, and lipid-anchored)
- Cholesterol molecules (increases fluidity and stability)
Selective Permeability:
- Allows certain molecules to pass through (e.g., water, oxygen, glucose)
- Restricts passage of other molecules (e.g., toxins, ions)
- Active transport: uses energy to move molecules against concentration gradient
- Passive transport: movement of molecules down concentration gradient (diffusion, osmosis)
Fluid Mosaic Model:
- Phospholipid bilayer is fluid and dynamic, with proteins and lipids able to move laterally
- Proteins are embedded in the bilayer, with some extending across the membrane
- Cholesterol molecules help maintain fluidity and stability
Cell Membrane
Functions:
- Regulates what enters and leaves the cell
- Provides structural support and maintains cell shape
- Acts as a barrier between internal cellular components and external environment
- Enables cell signaling and communication with other cells
Composition:
- Consists of a phospholipid bilayer with hydrophilic heads and hydrophobic tails
- Embedded with transmembrane, peripheral, and lipid-anchored proteins
- Contains cholesterol molecules to increase fluidity and stability
Selective Permeability:
- Allows water, oxygen, and glucose to pass through
- Restricts the passage of toxins and ions
- Uses active transport to move molecules against concentration gradient
- Employs passive transport for movement of molecules down concentration gradient
Fluid Mosaic Model:
- Phospholipid bilayer is fluid and dynamic
- Proteins and lipids can move laterally within the bilayer
- Proteins are embedded in the bilayer, with some spanning across the membrane
- Cholesterol molecules maintain fluidity and stability
Explore the composition and functions of the cell membrane, including selective permeability, structural support, and cell signaling. Learn about the phospholipid bilayer and embedded proteins.
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