What is Facilitated Diffusion _ It’s Meaning and Definition Transport of substances across
What is Facilitated Diffusion _ It’s Meaning and Definition Transport of substances across.
Contents [hide]
- 1 Facilitated Diffusion – Meaning & Definition
- 2 Definition of Facilitated Diffusion:
- 3 Characteristics of Facilitated Diffusion:
- 4 Types of Transport Proteins in Facilitated Diffusion:
- 5 Examples of Facilitated Diffusion:
- 6 Difference Between Simple Diffusion & Facilitated Diffusion:
- 7 Importance of Facilitated Diffusion in Cells:
Facilitated Diffusion – Meaning & Definition
Facilitated diffusion is a type of passive transport where molecules move across a cell membrane with the help of specific transport proteins. This process does not require energy (ATP) and helps transport molecules that cannot pass through the lipid bilayer on their own.
Definition of Facilitated Diffusion:
Facilitated diffusion is the process by which substances move across a biological membrane through specific carrier or channel proteins, following the concentration gradient (from higher concentration to lower concentration) without requiring energy.
Characteristics of Facilitated Diffusion:
Passive Transport – No energy (ATP) is needed.
Uses Transport Proteins – Helps large, polar, or charged molecules cross the membrane.
Follows Concentration Gradient – Moves from high to low concentration.
Faster than Simple Diffusion – Due to the assistance of proteins.
Types of Transport Proteins in Facilitated Diffusion:
Carrier Proteins – Bind to specific molecules, change shape, and transport them across.
- Example: Glucose transporter (GLUT) helps glucose enter cells.
Channel Proteins – Form pores or tunnels for molecules to pass through.
- Example: Ion channels (like sodium and potassium channels) help in nerve signaling.
Examples of Facilitated Diffusion:
Glucose Transport – Glucose enters cells through GLUT transporters.
Ion Transport – Sodium (Na⁺), Potassium (K⁺), and Calcium (Ca²⁺) move through ion channels.
Oxygen & Carbon Dioxide Exchange – Some gases move through aquaporins (water channels).
Difference Between Simple Diffusion & Facilitated Diffusion:
| Feature | Simple Diffusion | Facilitated Diffusion |
|---|---|---|
| Energy Requirement | No ATP required | No ATP required |
| Transport Proteins | Not needed | Required (carrier or channel proteins) |
| Molecule Type | Small, non-polar molecules | Large, polar, or charged molecules |
| Speed of Transport | Slower | Faster (due to proteins) |
| Example | Oxygen (O₂), Carbon Dioxide (CO₂) | Glucose, Ions (Na⁺, K⁺, Ca²⁺) |
Importance of Facilitated Diffusion in Cells:
Helps in nutrient absorption (e.g., glucose in the intestines).
Maintains ion balance (important for nerve signaling and muscle function).
Regulates water movement through aquaporins.
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