Facilitated diffusion is a passive transport process that allows substances to cross biological membranes with the assistance of special proteins, known as transport proteins or channels. Unlike simple diffusion, which occurs directly through the lipid bilayer, facilitated diffusion enables larger or polar molecules, such as glucose and ions, to move across the membrane without the expenditure of energy. This process relies on the concentration gradient, meaning substances will move from areas of higher concentration to areas of lower concentration until equilibrium is reached. The specificity of the transport proteins ensures that only certain molecules can pass through, thereby maintaining cellular homeostasis and regulating the internal environment of the cell
What is facilitated diffusion?
Facilitated diffusion is a passive transport process that allows substances to cross biological membranes with the help of transport proteins, moving from areas of higher concentration to lower concentration without the use of energy.
What types of molecules typically undergo facilitated diffusion?
Larger or polar molecules, such as glucose and ions, typically undergo facilitated diffusion because they cannot easily pass through the lipid bilayer of the cell membrane.
How do transport proteins function in facilitated diffusion?
Transport proteins function by providing a pathway for specific molecules to cross the membrane. They can either form channels that allow molecules to pass through or act as carriers that change shape to transport the molecules across the membrane.
Is energy required for facilitated diffusion?
No, facilitated diffusion is a passive process, meaning it does not require energy (ATP) to occur; it relies on the concentration gradient of the molecules being transported.
What is the role of the concentration gradient in facilitated diffusion?
The concentration gradient is crucial in facilitated diffusion as it drives the movement of molecules from areas of higher concentration to areas of lower concentration until equilibrium is reached.
Which type of molecules typically undergo facilitated diffusion?
a) Small nonpolar molecules
b) Large polar molecules and ions
c) Gases like oxygen and carbon dioxide
d) Lipids
Answer: b) Large polar molecules and ions
What role do transport proteins play in facilitated diffusion?
a) They consume energy to transport molecules
b) They provide a pathway for specific molecules to cross the membrane
c) They change the chemical structure of the molecules
d) They prevent any movement across the membrane
Answer: b) They provide a pathway for specific molecules to cross the membrane
Is energy required for facilitated diffusion to occur?
a) Yes, it requires ATP
b) No, it is a passive process
c) Only in certain conditions
d) Yes, but only for ions
Answer: b) No, it is a passive process
What drives the movement of molecules in facilitated diffusion?
a) Electrical gradients
b) Concentration gradients
c) Temperature changes
d) Pressure differences
Answer: b) Concentration gradients
Can facilitated diffusion occur in both directions across a membrane?
a) Yes, depending on the concentration gradient
b) No, it can only occur in one direction
c) Yes, but only for small molecules
d) No, it is a one-way process
Answer: a) Yes, depending on the concentration gradient