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Questions and Answers
What is the primary function of the cell membrane's semipermeability?
What is the primary function of the cell membrane's semipermeability?
What is the term for the movement of molecules down their concentration gradient without using energy?
What is the term for the movement of molecules down their concentration gradient without using energy?
Passive transport
The cell membrane is completely impermeable to all molecules.
The cell membrane is completely impermeable to all molecules.
False (B)
The ______________ model describes the phospholipid bilayer as dynamic and fluid, allowing molecules to move within the membrane.
The ______________ model describes the phospholipid bilayer as dynamic and fluid, allowing molecules to move within the membrane.
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What is the term for the changes in membrane shape and structure that can influence cell behavior and function?
What is the term for the changes in membrane shape and structure that can influence cell behavior and function?
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Lipid rafts are regions of the membrane with uniform lipid and protein compositions.
Lipid rafts are regions of the membrane with uniform lipid and protein compositions.
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What are the two types of proteins embedded in the cell membrane?
What are the two types of proteins embedded in the cell membrane?
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Match the following cell membrane functions with their descriptions:
Match the following cell membrane functions with their descriptions:
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Study Notes
Cell Membrane
Structure
- Phospholipid bilayer: composed of two layers of phospholipid molecules with their hydrophilic (water-loving) heads facing outwards and hydrophobic (water-fearing) tails facing inwards
- Embedded proteins: integral proteins (span the membrane) and peripheral proteins (attached to the surface)
Functions
- Semipermeability: regulates the movement of molecules in and out of the cell
- Protection: provides a barrier against external environment and maintains internal cellular environment
- Cell signaling: involved in cell-to-cell communication and signaling pathways
- Cell recognition: helps cells recognize and respond to their environment
Permeability
- Selective permeability: allows certain molecules to pass through while restricting others
- Passive transport: movement of molecules down their concentration gradient (e.g. diffusion, osmosis)
- Active transport: movement of molecules against their concentration gradient using energy (e.g. pumps, transport proteins)
Fluidity and Flexibility
- Fluid mosaic model: the phospholipid bilayer is dynamic and fluid, allowing molecules to move within the membrane
- Lipid rafts: specialized regions of the membrane with distinct lipid and protein compositions
- Membrane curvature: changes in membrane shape and structure can influence cell behavior and function
Cell Membrane
Structure
- Phospholipid bilayer is composed of two layers of phospholipid molecules with hydrophilic heads facing outwards and hydrophobic tails facing inwards
- Integral proteins span the membrane, while peripheral proteins are attached to the surface
Functions
- Semipermeability allows the cell membrane to regulate molecular movement in and out of the cell
- Provides protection by maintaining internal cellular environment and acts as a barrier against external environment
- Involved in cell-to-cell communication and signaling pathways through cell signaling
- Enables cell recognition and response to environment
Permeability
- Selective permeability allows certain molecules to pass through while restricting others
- Passive transport occurs through diffusion and osmosis, moving molecules down their concentration gradient
- Active transport moves molecules against their concentration gradient using energy, involving pumps and transport proteins
Fluidity and Flexibility
- Fluid mosaic model depicts the phospholipid bilayer as dynamic and fluid, allowing molecule movement within the membrane
- Lipid rafts are specialized regions with distinct lipid and protein compositions
- Changes in membrane curvature influence cell behavior and function
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Description
Understand the composition and roles of the cell membrane, including its phospholipid bilayer, embedded proteins, semipermeability, and protection functions.
