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Cell Transport Notes
Homeostasis
 All living things, from cells to large organisms, maintain very stable internal
conditions
 _________________
 Water content
 _________ _____________
 Salt levels
 ________________: __________ level of internal ________________
Homeostasis and Cell Transport
 Cell membranes help organisms ________________ homeostasis by
______________ what _________________ may enter or leave cells
 Water and other substances are moved in and out of a cell in two ways:
1. _________________ transport
2. _________________ transport
Passive Transport
 Passive transport: when substances can cross the membrane
_________________ _________________from the cell
 Types of Passive transport
1. ____________________
2. ________________ ________________
3. _____________
Diffusion
 Diffusion: _____________________ ________ _________________ (______
WATER) from an area of _________ concentration to an area of _______
concentration
 Requires _____ ___________
High  Low
Concentration Gradient
 Concentration Gradient: The ________________ in concentration of
molecules across a space
 When molecules go from _______ concentration to _____ concentration,
they are said to be moving __________ the concentration gradient
Equilibrium
 Equilibrium: Eventually the _____________________ of molecules will be the
__________ (equally spread out)
 this balance in concentration is called Equilibrium
Diffusion Across Membranes
 The _______________ of a molecule ___ ___________ across a cell membrane
depends on the _____, type, and chemical nature of the molecule
 Molecules that are small such as _______ and ______ will pass through the
membrane by diffusion
 Very _____ _____________ like _____________ or ions (charged particles)
may _______ be able to get through by ________________
Facilitated Diffusion
 Facilitated Diffusion: ___________ across a membrane with help of
______________ proteins
 Used for molecules that are not soluble in lipids or are too large to pass
through the pores in the membrane
 Substances move down the concentration gradient (______ ____ _____)
 _____ __________
Osmosis
 Osmosis: diffusion of _______________ across a membrane from areas of
_______water concentration to areas of _______ water concentration
 _____ __________
High  Low
Molecular Movement in Cells
 ______________ solution: ___________ concentration of __________
_________cell
 WATER _________ ________ cell
 Water will go from ______ to ______ concentration until equilibrium is
established
 Hypertonic solution: ___________ concentration of _________ _______ cell
 WATER ________ ______ OF cell
 Water will go from _______ to ______ concentration until equilibrium is
established
 Isotonic solution: _________ ____________of WATER inside and outside cell
 WATER ______________ _____________
Active Transport
 Active Transport: movement of molecules from an area of _____
concentration to an area of ______ concentration
 _________ __________!!!
 ________
Low  High
Concentration Gradient
 Concentration Gradient: The difference in concentration of molecules across
a space
 When molecules go from _______ concentration to _______
concentration, they are said to be moving _____
__________________________
Active Transport
 Cell Membrane Pumps
 Proteins in the cell membrane that move (pump) substances up the
concentration gradient
 ______ __________ _____ to work
Active Transport of Macromolecules
 Some molecules (such as proteins, lipids, carbohydrates, etc….) are too large
to cross the cell membrane by passive transport or by active transport
through cell membrane pumps.
 These macromolecules move across the membrane in two ways
1.
_____________________
2.
_____________________
Endocytosis
 When a cell engulfs a substance and _________ ____ _____
 A type of active transport because it ___________ _____
Types of Endocytosis
 _________________
 transport of fluid into the cell (______________)
 _________________
 engulfment of large particles or cells into the cell (______________)
_________________
 When a cell _______ ________ a particle
 Getting rid of solid wastes
 Vesicles in the cytoplasm fuse with the cell membrane, releasing their
contents out of the cell