Cellular Transport Notes Homeostasis, Passive Transport, Diffusion, Osmosis, & Active Transport

Learning Questions How do cells maintain homeostasis in changing environments? How do cells take in nutrients in order to grow and divide and to make needed materials? How do you explain the relationship between the structures and functions of cell organelles?

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Objective of the Unit Explain that cells need to maintain homeostasis Explain passive transport and diffusion Define the process of osmosis Explain the process of active transport and the role of ATP Explain the processes of endocytosis and exocytosis

CELLS AND THEIR ENVIRONMENT: HOMEOSTASIS

LIFE’S BALANCING ACT If you are too hot or too cold your body temperature is out of balance

2 examples of homeostasis When we are too cold we shiver, it warms us up When we are too hot we sweat, it cools us down. 2 examples of homeostasis

Sweating and shivering are the body’s response to extreme temperature. They help the body return to a temperature that is comfortable. Sweating and shivering are the body’s response to extreme temperature. The body is balanced

HOMEOSTASIS The balance that all living things must maintain is called HOMEOSTASIS.

Importance of CELL BALANCE Your body is made up of cells that must stay balanced. They need the right amount of materials to maintain the proper environment for your body.

Objective of the Unit Explain that cells need to maintain homeostasis Explain passive transport and diffusion Define the process of osmosis Explain the process of active transport and the role of ATP Explain the processes of endocytosis and exocytosis

Concentration Gradient: The difference between the regions of high concentration and low concentration The steeper the concentration gradient, the faster diffusion takes place High concentration gradient Fast rate of diffusion Low concentration gradient Slow rate of diffusion

“Selectively Permeable” Membranes “Semi-Permeable” or “Selectively Permeable” Membranes A semi-permeable membrane will allow certain molecules to pass through it, but not others. Partially permeable membrane Generally, small particles can pass through… …but large particles cannot

Cellular Transport! The process by which molecules move from one side of the cell membrane to the other Two Types Include: Passive Active

Passive Transport

Passive Transport Two Types Include: Doesn’t require energy Molecules move from high to low concentration Analogy: Like coasting down hill on a bike! Two Types Include: Diffusion Osmosis

Diffusion The passive movement of MOLECULES along a concentration gradient, or from regions of high to low concentration. EX: Spraying air freshener

Diffusion occurs because the particles in gases and liquids are moving.

Diffusion Particles in a liquid or gas spread out… … from regions of high concentration… … to regions of low concentration… …until the particles are evenly spread out.

Osmosis- A type of diffusion Osmosis is the DIFFUSION of WATER molecules… … from a region of high concentration to low concentration …across a semi-permeable membrane… …until they are evenly spread out.

Passive Transport Does osmosis or diffusion require energy? No, molecules move along a concentration gradient (high to low).

Free water molecules diffuse in this direction Partially-permeable membrane More free water molecules on this side of membrane Water-solute particle is too large to pass through membrane Free water molecules diffuse in this direction

Complete the definition Osmosis is the movement of water molecules from a region of high concentration to low concentration across a semi-permeable membrane. answer