Chapter 3 Cell Structure and Function pt. 2
Materials move across membranes because of concentration differences
Passive transport: The movement of molecules across a cell membrane without energy input from the cell.
Saves cells a lot of energy.
Diffusion: The movement of molecules in a fluid or gas from a region of higher concentration to a region of lower concentration.
When particles move and collide, they scatter to places where there are less particles.
Diffusion is passive transport
Concentration gradient: The difference in concentration of a substance from one location to another.
Diffusion is important for moving substances across the membrane.
Substances that aren’t highly concentrated in a cell are more likely to diffuse in a cell (Ex. oxygen).
Osmosis: The diffusion of water molecules.
Like other molecules, water molecules will go to areas with lower water concentration
There are different ways a solution can be identified as:
Isotonic: When a solution has the same concentration of dissolved particles as the cell.
The cell’s size remains constant as the water comes and goes at an equal rate.
Hypertonic: When a solution has a higher concentration of dissolved particles than a cell.
Water flows out of the cell at a faster rate which causes the cell to shrivel.
Hypotonic: When a solution has a lower concentration of dissolved particles than a cell.
More water flows into the cell which expands or even bursts the cell.
Certain molecules cross easier through the membrane by transporting proteins.
Facilitated diffusion: The diffusion of molecules across a membrane through transport proteins.
Still a form a passive transport (No energy is required).
Cells use energy to transport materials that cannot diffuse across a membrane.
Pumps are transport proteins that move materials AGAINST a concentration gradient.
Active transport: Moves molecules across a membrane from an area of lower concentration to an area of higher concentration.
Active transport proteins move the molecules with chemical energy.
Transport in vesicles lets substances enter or leave a cell without having to cross the membrane.
Endocytosis: The process of taking liquids or fairly large molecules into a cell by surrounding them in a membrane.
Phagocytosis: A type of endocytosis where the cell membrane surrounds large particles.
Think endo = in
Exocytosis: The release of substances out of a cell by sending materials out of the membrane through a vesicle.
The exact opposite of Endocytosis
Vesicles fuse with the cell membrane and releases substances outside of the cell.
Think exo = out
Materials move across membranes because of concentration differences
Passive transport: The movement of molecules across a cell membrane without energy input from the cell.
Saves cells a lot of energy.
Diffusion: The movement of molecules in a fluid or gas from a region of higher concentration to a region of lower concentration.
When particles move and collide, they scatter to places where there are less particles.
Diffusion is passive transport
Concentration gradient: The difference in concentration of a substance from one location to another.
Diffusion is important for moving substances across the membrane.
Substances that aren’t highly concentrated in a cell are more likely to diffuse in a cell (Ex. oxygen).
Osmosis: The diffusion of water molecules.
Like other molecules, water molecules will go to areas with lower water concentration
There are different ways a solution can be identified as:
Isotonic: When a solution has the same concentration of dissolved particles as the cell.
The cell’s size remains constant as the water comes and goes at an equal rate.
Hypertonic: When a solution has a higher concentration of dissolved particles than a cell.
Water flows out of the cell at a faster rate which causes the cell to shrivel.
Hypotonic: When a solution has a lower concentration of dissolved particles than a cell.
More water flows into the cell which expands or even bursts the cell.
Certain molecules cross easier through the membrane by transporting proteins.
Facilitated diffusion: The diffusion of molecules across a membrane through transport proteins.
Still a form a passive transport (No energy is required).
Cells use energy to transport materials that cannot diffuse across a membrane.
Pumps are transport proteins that move materials AGAINST a concentration gradient.
Active transport: Moves molecules across a membrane from an area of lower concentration to an area of higher concentration.
Active transport proteins move the molecules with chemical energy.
Transport in vesicles lets substances enter or leave a cell without having to cross the membrane.
Endocytosis: The process of taking liquids or fairly large molecules into a cell by surrounding them in a membrane.
Phagocytosis: A type of endocytosis where the cell membrane surrounds large particles.
Think endo = in
Exocytosis: The release of substances out of a cell by sending materials out of the membrane through a vesicle.
The exact opposite of Endocytosis
Vesicles fuse with the cell membrane and releases substances outside of the cell.
Think exo = out
