Cell Transport Mechanisms

Flashcards covering key concepts about diffusion, osmosis, and cell transport mechanisms.

What is diffusion?

The movement of molecules from an area of high concentration to an area of low concentration.

What is meant by the rate of diffusion?

The speed at which molecules move from high concentration to low concentration.

How can the rate of diffusion be increased?

By increasing temperature, surface area, or concentration gradient.

When does diffusion occur in cells?

It occurs constantly as molecules move in and out of cells.

What is the difference in concentration across the membrane called?

Concentration gradient.

Why is movement of materials across a cell membrane through diffusion called passive transport?

Because it does not require energy.

What does it mean that the cell membrane is selectively permeable?

It allows certain substances to pass while blocking others.

What determines whether particles can pass through the membrane?

Particle size, charge, and solubility in lipid.

Describe the movement of carbon dioxide and oxygen across the cell membrane.

They diffuse across the membrane from areas of high concentration to low concentration.

What does it mean that the cell is an open system?

It exchanges matter and energy with its surroundings.

What is osmosis?

Movement of water molecules from an area of high water concentration to low water concentration.

What is the main difference between osmosis and diffusion?

Osmosis specifically refers to water movement, while diffusion refers to all types of molecules.

What is a hypertonic cell?

A cell that is surrounded by a solution with a higher concentration of solutes.

What is a hypotonic cell?

A cell that is surrounded by a solution with a lower concentration of solutes.

What is an isotonic cell?

A cell surrounded by a solution with equal solute concentration, causing no net movement of water.

What is turgor pressure?

The pressure exerted by the fluid inside the central vacuole against the cell wall.

What type of substances pass through the membrane by facilitated diffusion?

Large or polar molecules that cannot directly pass through the lipid bilayer.

What are channel proteins?

Proteins that create passageways for specific molecules to cross the membrane.

What are carrier proteins?

Proteins that bind to molecules and change shape to shuttle them across the membrane.

What is the difference between facilitated diffusion and diffusion?

Facilitated diffusion requires specific proteins, while simple diffusion does not.

What is active transport?

The movement of molecules against their concentration gradient, requiring energy.

What is the difference between active transport and previously mentioned transport mechanisms in terms of concentration gradient?

Active transport moves substances from low to high concentration, unlike passive transport.

Where does the cell receive its energy from?

Typically from ATP generated during cellular respiration.

What must be used by the cell when molecules are too large?

Vesicles.

Describe the use of vesicles.

They transport large molecules into and out of the cell.

Describe the process of endocytosis.

The process by which cells engulf materials from the outside environment.

Describe the process of exocytosis.

The process by which cells expel materials to the outside environment.

Do these processes require energy? If so, in what form?

Yes, they require energy in the form of ATP.