Cellular Transport

Homeostasis The need of an organism to maintain and regulate constant or stable internal conditions. Example – body temperature Much of homeostasis is maintained by the cell membrane controlling movement of things in and out of the cell

Cell Membrane The cell membrane is said to be selectively permeable, meaning certain substances can move across it freely, while others must move through a “gate”. Two types of transport Passive transport Active transport

Cellular Transport Passive Transport requires no energy molecules move from high concentration (squished together) to low concentration (spread out) down the concentration gradient Active Transport requires energy (ATP) Molecules move from low concentration to high concentration against the concentration gradient

Types of Transport Passive Transport Active Transport Diffusion Osmosis Facilitated Diffusion Active Transport Molecular Pumps Exocytosis Endocytosis

Words to Know Solute – what gets dissolved Ex. Lemonade powder Solvent – does the dissolving Ex. Water Solution – uniform mixture of two or more substances Ex. Lemonade Concentration – amount of solute dissolved in solvent

Passive Transport: Diffusion Molecules move down a concentration gradient Go from high concentration to low concentration

Passive Transport: Diffusion

Passive Transport: Facilitated Diffusion A transport protein acts as a protein channel to help (facilitate) the diffusion of molecules that normally couldn‘t pass through the cell membrane Ex. Glucose/sugar, sodium/salt Molecules move down a concentration gradient, Go from high concentration to low concentration

Passive Transport: Facilitated Diffusion

Passive Transport: Osmosis The diffusion of water across the cell membrane Water molecules move down a concentration gradient, Go from high concentration to low concentration

Passive Transport: Osmosis

Passive Transport: Osmosis Types of osmosis solutions Hypertonic solution Hypotonic solution Isotonic solution

Passive Transport: Osmosis Hypertonic solutions: water concentration is lower inside the cell compared to outside the cell Water will move out of the cell, down its concentration gradient  Cell shrivels

Passive Transport: Osmosis Hypotonic solutions: water concentration is higher inside the cell compared to outside the cell Water will move into a cell, down its concentration gradient  Cell swells

Passive Transport: Osmosis Isotonic solutions: water concentration inside the cell is the same as outside the cell Water will moves in both directions  cell stays the same

Passive Transport: Osmosis Hypertonic Hypotonic Isotonic H2O H2O H2O H2O H2O H2O Cell stays the same Cell shrivels Cell swells

Active Transport Molecules move AGAINST the concentration gradient From low concentration to high concentration

Active Transport: Molecular Pumps When a cell uses energy to pump molecules across the membrane through a protein channel This allows a cell to concentrate key molecules within the cell, or remove waste quickly from the cell

Active Transport: Endocytosis A cell uses energy to import large amounts of materials INTO the cell using a vesicle Ex. White blood cells engulf bacteria to fight infection

Active Transport: Exocytosis A cell uses energy to export large amounts of materials OUT OF the cell using a vesicle Ex. Nerve cells release neurotransmitters to pass signals to the brain