Movement Across Membranes Flashcards
What are the four types of movements?
Diffusion
Osmosis
Active transport
Facilitated diffusion
What is the definition of diffusion?
Random movement of molecules down the concentration gradient until dynamic equilibrium is reached
What is down the concentration gradient?
From a high to a low concentration
What is dynamic equilibrium?
When a substance is spread equally within another substance
What is the definition of facilitated diffusion?
Movement of molecules down the concentration gradient until a dynamic equilibrium is reached, but with the assistance of a protein
What is the definition of osmosis?
Movement of WATER molecules down the WATER concentration gradient through a selectively-permeable membrane until dynamic equilibrium is reached
What is the definition of active transport?
Movement of molecules up the concentration gradient until dynamic equilibrium is reached. ATP is needed for this process.
What is the definition of a solute?
A substance which has dispersed its molecules throughout a solvent
What is the definition of a solution?
A mixture of a solute and a solvent
What is the definition of hypertonic?
A substance in which there is a high concentration of solute
What is the definition of hypotonic?
A substance in which there is a low concentration of solute
What is the definition of isotonic?
A substance which has an equal concentration of water and solute to that of the inside of a cell
What is the definition of water potential?
The likelihood of a substance to donate its water particles to another substance
What is the definition of concentration gradient?
The process of movement of particles to and from areas of differing concentration
What is a hypertonic solution?
A substance in which there is a high concentration of solute and a low concentration of water in comparison with the inside of a cell
What is a hypotonic solution?
A substance in which there is a low concentration of solute and a high concentration of water in comparison with the inside of a cell
What are free water molecules?
Water molecules that do not have solute to ‘bind’ to
What are the five important points to remember when defining osmosis?
Water molecules move High water potential to Low water potential Across a selectively permeable membrane Until dynamic equilibrium is reached
What is the first step when answering osmosis questions?
Identify which substance has a high water potential and which has a low water potential
What is the “formula” for answering osmosis questions?
Use the definition and slot in the information given
In terms of osmosis, what is dynamic equilibrium?
For every water molecule that crosses over to one side, another water molecule will cross over from that side to the original side
Why does diffusion take place?
Every molecule has kinetic energy
What affects the rate of diffusion?
The steepness of the concentration gradient
What is the concentration gradient?
The difference between the concentration of molecules in different areas
What kind of transport is diffusion?
Passive
What is water potential?
The ability of a solution to release water given its large number of free water molecules
What is the symbol for water potential?
Ψ
What substance has the highest water potential?
Pure water
