Transport Proteins and Membrane Function

The video discusses passive transport, focusing on simple diffusion and facilitated diffusion. It explains how small, non-polar molecules easily diffuse through cell membranes, while charged particles face challenges. Facilitated diffusion is introduced as a way to ease transport for certain molecules, using channel and carrier proteins. Channel proteins, like aquaporins, allow water and ions to pass through membranes, while carrier proteins change shape to transport substances down their concentration gradient.

Which type of molecules can easily pass through the cellular membrane via simple diffusion?

• Proteins

• Charged ions

• Small non-polar molecules

• Large polar molecules

Why do charged particles have difficulty passing through the cellular membrane?

• They are not affected by the concentration gradient.

• They interact with the phosphate heads due to their charge.

• They are repelled by the hydrophobic tails.

• They are too large to fit through the membrane gaps.

What is the role of channel proteins in facilitated diffusion?

• They use energy to transport molecules.

• They create tunnels for specific molecules to pass through the membrane.

• They break down molecules before transport.

• They repel unwanted molecules.

What is an aquaporin?

• A molecule that blocks diffusion

• A channel protein specifically for water molecules

• A protein that breaks down solutes

• A type of carrier protein for ions

How do channel proteins assist in nerve cell function?

• They convert electrical signals into chemical signals.

• They block ion flow to prevent signal transmission.

• They amplify electrical signals by allowing ion flow.

• They store electrical signals.

What feature allows channel proteins to regulate ion flow?

• They change shape to fit different ions.

• They use ATP to control flow.

• They can be gated to open or close based on conditions.

• They are always open.

What is the primary function of carrier proteins in facilitated diffusion?

• To use energy to move molecules against the gradient

• To change shape and transport molecules across the membrane

• To break down molecules before transport

• To repel unwanted molecules

How do carrier proteins differ from channel proteins?

• Carrier proteins change shape to transport molecules, while channel proteins provide a tunnel.

• Carrier proteins are always open, while channel proteins are gated.

• Carrier proteins are specific to ions, while channel proteins are not.

• Carrier proteins use energy, while channel proteins do not.

What triggers a carrier protein to change its shape?

• The presence of ATP

• The attachment of a molecule to the protein

• The presence of light

• A change in temperature

In facilitated diffusion, what drives the movement of molecules?

• Movement down the concentration gradient

• Random molecular motion

• Movement against the concentration gradient

• Energy from ATP