Transport Mechanisms in Cell Membranes

Why do cells need to transport materials across the plasma membrane?

• To divide and reproduce

• To create and use energy

• To communicate with other cells

• To maintain their shape

Which of the following molecules can easily pass through the plasma membrane?

• Glucose

• Oxygen

• Proteins

• Starch

What is a characteristic of small molecules like oxygen and carbon dioxide in relation to the plasma membrane?

• They can slide across easily

• They are blocked by the membrane

• They need carrier proteins

• They require energy to pass through

Why can't larger molecules like food pass through the plasma membrane easily?

• They are repelled by the membrane

• They are too large to fit through the tightly packed phospholipids

• They dissolve in the membrane

• They are broken down before passing through

What role do proteins play in the transport of larger molecules across the plasma membrane?

• They break down the molecules

• They repel the molecules

• They dissolve the molecules

• They form channels or act as carriers

What is the function of channel proteins?

• To dissolve molecules

• To repel unwanted substances

• To form openings for larger molecules to pass through

• To break down molecules

How do carrier proteins assist in the transport of larger molecules?

• They repel the molecules

• They break down the molecules

• They pick up and carry the molecules across the membrane

• They form channels

What happens to a molecule when it is picked up by a carrier protein?

• It is broken down

• It is carried across the membrane and dropped off on the other side

• It is repelled

• It is dissolved

What is the main takeaway regarding the transport of materials across the plasma membrane?

• Only small molecules can pass through

• All molecules require energy to pass through

• The membrane repels all foreign substances

• Larger molecules need help from proteins

What will be discussed in the next tutorial?

• Different methods of transportation across the plasma membrane

• The structure of the plasma membrane

• The process of cell division

• The role of lipids in the membrane