7 Questions
What is the main characteristic of facilitated diffusion?
It uses transport proteins to move molecules down their concentration gradient.
What type of transport protein forms a hydrophilic channel across the membrane?
Channel protein
What occurs when a cell is placed in a hypotonic solution?
Water enters the cell.
What is the purpose of osmosis in cells?
To maintain proper balance of fluids within cells.
What type of molecules can diffuse through the phospholipid bilayer of the cell membrane?
Small, non-polar molecules.
What is the main difference between facilitated diffusion and simple diffusion?
The presence of transport proteins.
What is the term for a solution with an equal concentration of solutes on both sides of the membrane?
Isotonic
Study Notes
Passive Transport
Facilitated Diffusion
- Also known as facilitated transport or passive-mediated transport
- Movement of molecules down their concentration gradient with the assistance of transport proteins
- No energy is required, as it is a spontaneous process
- Types of transport proteins:
- Channel proteins: form a hydrophilic channel across the membrane
- Carrier proteins: bind to molecules and change shape to facilitate transport
Osmosis
- Movement of water molecules from an area of high concentration to an area of low concentration through a selectively permeable membrane
- Helps maintain proper balance of fluids within cells
- Types of osmotic situations:
- Isotonic: equal concentrations of solutes on both sides of the membrane
- Hypotonic: lower concentration of solutes outside the cell
- Hypertonic: higher concentration of solutes outside the cell
Simple Diffusion
- Movement of molecules from an area of high concentration to an area of low concentration
- No transport proteins are involved
- Occurs through the phospholipid bilayer of the cell membrane
- Types of molecules that can diffuse:
- Small, non-polar molecules (e.g. oxygen, carbon dioxide)
- Hydrophobic molecules (e.g. steroids)
Passive Transport
Facilitated Diffusion
- Facilitated diffusion is a spontaneous process that moves molecules down their concentration gradient with the help of transport proteins.
- No energy is required for this process.
- There are two types of transport proteins: channel proteins and carrier proteins.
- Channel proteins form a hydrophilic channel across the membrane, allowing molecules to pass through.
- Carrier proteins bind to molecules and change shape to facilitate transport.
Osmosis
- Osmosis is the movement of water molecules from an area of high concentration to an area of low concentration through a selectively permeable membrane.
- Osmosis helps maintain the proper balance of fluids within cells.
- There are three types of osmotic situations: isotonic, hypotonic, and hypertonic.
- In an isotonic solution, the concentration of solutes is equal on both sides of the membrane.
- In a hypotonic solution, the concentration of solutes is lower outside the cell.
- In a hypertonic solution, the concentration of solutes is higher outside the cell.
Simple Diffusion
- Simple diffusion is the movement of molecules from an area of high concentration to an area of low concentration.
- This process occurs through the phospholipid bilayer of the cell membrane.
- No transport proteins are involved in simple diffusion.
- Small, non-polar molecules such as oxygen and carbon dioxide can diffuse through the cell membrane.
- Hydrophobic molecules like steroids can also diffuse through the cell membrane.
Understand the concepts of facilitated diffusion and osmosis, including types of transport proteins and how they assist in the movement of molecules across cell membranes.
Make Your Own Quizzes and Flashcards
Convert your notes into interactive study material.
Get started for free
