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Unit 3: Cells
Cell Transport
The Goalof cell transport
Homeostasis Stable internal conditions*
* Such as temperature and water
Passive Transport
Definition• Movement across a cell
membrane with NO energy• Goes from high to low
concentration
Types of Passive Transport• Diffusion• Osmosis• Facilitated channels• Ion channels
Passive Transport: Diffusion
Definition• Movement from an high
concentration to an area of low concentration
Passive Transport: Osmosis
Definition• Process of WATER moving
from high to low concentration
• Hypotonic osmosis: water moves INTO the cell
and it swells.
• Hypertonic osmosis: water moves OUT off a cell.
• The cell shrinks.
Isotonic osmosis: solution and cell are both at homeostasis.
Passive Transport: Facilitated Diffusion
Definition• Diffusion with the help of a
busser protein
Busser protein
• Passageway in a membrane for ions* to pass through
• Ion = any atom with a charge (+ or -)
• Example: sodium (Na + or potassium K+)
Passive Transport: Ion Channel
Definition
Active Transport
Definition• Substances moving across
the cell membrane with energy
• Goes from low to high concentration
Types of Active Transport• Cell membrane pump• Endocytosis• Exocytosis
Active Transport: Cell-Membrane Pump
Definition• Bussers pump molecules
across the membrane from LOW to HIGH
Active Transport: Endocytosis
• Definition• The process in which
cells ingest (take in) molecules
• 2 types• Pinocytosis – cells
take in liquids • Endocytosis – cells
take in solids
Active Transport: ExocytosisDefinition
• Cells expel (get rid of) molecules