Facilitated Diffusion - AP Biology

Is facilitated diffusion specific to certain molecules?

Yes, it is selective. Proteins have specific binding sites for target molecules.
Identify one similarity between facilitated diffusion and osmosis.

Both are passive transport processes. Both use concentration gradients without energy input.
What is the role of the lipid bilayer in facilitated diffusion?

It acts as a barrier to polar or charged molecules. Prevents direct passage of hydrophilic molecules.
What is the difference between simple and facilitated diffusion?

Facilitated uses proteins; simple does not. Key distinction is protein requirement for selectivity.
Do carrier proteins require ATP to function?

No, not in facilitated diffusion. Facilitated diffusion is energy-independent.
Does facilitated diffusion involve a change in protein shape?

Yes, in carrier proteins. Conformational changes enable molecular transport.
Does facilitated diffusion increase or decrease with higher molecule concentration?

Increases until saturation. More substrate increases rate until protein saturation.
Identify a factor that affects the rate of facilitated diffusion.

Concentration gradient or number of transport proteins. Both determine transport speed and efficiency.
What is the role of facilitated diffusion in cellular respiration?

Transport of glucose into cells. Provides substrate for energy production pathways.
Identify a situation where facilitated diffusion is crucial in human physiology.

Glucose uptake in muscle cells. Critical for energy metabolism in active tissues.
What types of molecules use facilitated diffusion?

Polar or charged molecules. These cannot pass through lipid bilayers without protein assistance.
What is facilitated diffusion?

Passive transport via proteins without energy. Uses specific proteins to help molecules cross membranes down gradients.
What type of transport is facilitated diffusion?

Passive transport. No cellular energy required for this process.
What is the key difference between active transport and facilitated diffusion?

Active transport requires energy; facilitated does not. Energy distinguishes active transport from passive processes.
Identify the role of transport proteins in facilitated diffusion.

They assist in moving substances across membranes. Proteins provide selective pathways for specific molecules.
Can facilitated diffusion become saturated?

Yes, when all proteins are occupied. Limited number of proteins creates maximum transport rate.
What is a channel protein?

A protein that forms a pore for ions to pass through. Creates a selective tunnel through the membrane.
What is the role of membrane proteins in facilitated diffusion?

They facilitate the movement of molecules across the cell membrane. Essential components for selective membrane permeability.
Identify the effect of temperature on facilitated diffusion.

Higher temperatures generally increase rate. Heat increases molecular motion and protein activity.
Which molecules are transported by ion channels?

Ions such as Na $^+$ , K $^+$ , Ca $^{2+}$ . Charged particles that require channel proteins.
Which transport proteins are involved in facilitated diffusion?

Channel proteins and carrier proteins. Two main types that facilitate molecular transport.
Do channel proteins require binding to the transported molecule?

No, they do not require binding. Simply form pores without molecular binding.
What is the key structural feature of channel proteins?

They form pores in the membrane. Creates selective pathways through membrane structure.
What type of cell transport is facilitated diffusion classified as?

Passive transport. Category of transport requiring no cellular energy.
Can facilitated diffusion occur without a protein?

No, it requires a transport protein. Proteins are essential for this transport mechanism.
What is a carrier protein?

A protein that changes shape to move molecules. Undergoes conformational changes during transport.
Does facilitated diffusion require energy?

No, it is a passive process. Uses existing concentration gradients as driving force.
Describe the role of aquaporins in facilitated diffusion.

They facilitate water transport. Specialized channel proteins for rapid water movement.
What is the role of ion channels in facilitated diffusion?

They allow specific ions to pass through the membrane. Provide selective permeability for charged particles.
What is the role of glucose transporters?

They facilitate glucose transport across the membrane. Essential for cellular energy metabolism.
Does facilitated diffusion move molecules against the concentration gradient?

No, it moves with the concentration gradient. Follows natural diffusion from high to low concentration.
Identify a scenario where facilitated diffusion is vital.

Nerve impulse transmission. Requires rapid ion movement for electrical signals.
What is the concentration gradient?

Difference in concentration across a space. Drives passive transport from high to low concentration.
What is the function of gated channels?

They open or close in response to stimuli. Control molecular flow through stimulus-response mechanisms.
Are there any energy requirements for facilitated diffusion?

No, it is energy-independent. Passive process relying only on concentration gradients.
What limits the rate of facilitated diffusion?

Number of available transport proteins. Protein availability determines maximum transport capacity.
Do carrier proteins move multiple molecules simultaneously?

They typically move one molecule at a time. Each protein handles one molecule per transport cycle.
Identify one example of a molecule that uses facilitated diffusion.

Glucose. Large polar molecule requiring carrier protein assistance.
Identify a common feature of molecules that use facilitated diffusion.

They are typically hydrophilic. Water-loving molecules that cannot cross lipid bilayers.
Identify one condition that could inhibit facilitated diffusion.

Protein inhibitors or low temperatures. Factors that reduce protein function or molecular motion.
Identify the main factor that drives facilitated diffusion.

Concentration gradient. The driving force behind all passive transport.

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