Passive transport

What is passive transport?

Passive transport is the movement of molecules across a cell membrane without the use of energy.

Types of passive transport

Diffusion, facilitated diffusion, and osmosis are the main types of passive transport.

What is diffusion?

Diffusion is the movement of particles from an area of high concentration to an area of low concentration.

What is Simple diffusion ?

Simple diffusion is the process where particles move from an area of high concentration to an area of low concentration without the aid of transport proteins or energy.

What is facilitated diffusion?

Facilitated diffusion is the process of passive transport of molecules across a membrane via specific transport proteins.

What is osmosis?

Osmosis is the diffusion of water across a selectively permeable membrane.

Selective permeability

Selective permeability refers to the ability of a cell membrane to allow certain molecules to pass while blocking others.

Role of concentration gradient in passive transport

The concentration gradient drives the movement of molecules in passive transport, from high to low concentration.

What factors affect the rate of diffusion?

Temperature, concentration gradient, surface area, and the nature of the solvent can affect the rate of diffusion.

Example of a small molecule that uses diffusion

Oxygen and carbon dioxide are examples of small molecules that can diffuse easily across cell membranes.

Transport proteins in facilitated diffusion

Transport proteins help transport larger or polar molecules across the membrane in facilitated diffusion.

Aquaporins

Aquaporins are channel proteins that facilitate the transport of water across cell membranes.

What is isotonic solution?

An isotonic solution is one where the concentration of solutes is equal inside and outside of the cell.

What is hypertonic solution?

A hypertonic solution has a higher concentration of solutes outside the cell than inside.

What happens in a hypertonic solution?

In a hypertonic solution, cells lose water and can shrink or crenate.

What is hypotonic solution?

A hypotonic solution has a lower concentration of solutes outside the cell compared to inside.

What happens in a hypotonic solution?

In a hypotonic solution, cells can gain water and swell, potentially bursting.

Passive transport vs. active transport

Active transport requires energy to move substances against their concentration gradient, while passive transport does not.

Cation channels

Cation channels are specialized proteins that allow the flow of cations (positively charged ions) in facilitated diffusion.

Anion channels

Anion channels are specialized proteins that permit the movement of anions (negatively charged ions) across membranes.

Endocytosis and exocytosis relation to passive transport

While endocytosis and exocytosis involve vesicular transport and require energy, passive transport does not.

Diffusion rate and temperature relationship

As temperature increases, the rate of diffusion generally increases due to greater kinetic energy.

Concentration gradient importance

A steep concentration gradient generally results in a faster rate of passive transport.

What role do integral proteins play in passive transport?

Integral proteins facilitate the passage of specific molecules through the membrane during passive transport.

Role of lipid bilayer in passive transport

The lipid bilayer provides a barrier that selectively allows certain substances to diffuse across.

Examples of substances that cannot passively diffuse through a membrane

Ions and large polar molecules typically cannot passively diffuse through a lipid bilayer.

Factors influencing osmosis

The concentration of solutes in water and the presence of a semi-permeable membrane influence osmosis.

What is a concentration equilibrium?

Concentration equilibrium is reached when the concentrations of molecules on either side of the membrane are equal.

Implications of passive transport in cells

Passive transport is critical for maintaining cellular homeostasis and allows cells to regulate their internal environments.