Cellular Functions Biology Agriculture

Movement of Materials Diffusion Osmosis Passive Transport Active Transport Hypotonic Solution Hypertonic Solution Isotonic Solution Endocytosis Exocytosis

Group Assignment What is the function? Describe it and teach the class how that function works. How does it affect what happens in the cell? Give some examples of that cell function in real world application. You must have photos, diagrams and images of the function organized on a poster. You are required to come up with a lab for this presentation.

Movement of Materials All molecules are governed by the same physical laws. Knowing how they work will better help you understand cells.

Diffusion The process by which molecules of a substance move from areas of high concentration to areas with a low concentration. i.e. food coloring in water. Food coloring is the high concentration Water is the low concentration.

Equilibrium Concentration Gradient: Equilibrium: The difference in the concentration of molecules of a substance from highest to lowest. Equilibrium: When the concentration gradient equalizes.

Plasma Membranes Acts like a barrier Membranes control the passage of materials in and out of the cell. They are selectively permeable: They allow only certain substances to pass through them.

Osmosis The diffusion of water across a selectively permeable membrane.

Living Cells Isotonic Solution Hypotonic Solution Hypertonic Solution

Isotonic Solutions The rate of osmosis into the cell is exactly the same as the rate leaving the cell. As a result, no water movement takes place.

Hypotonic Solutions Water moves from the solution into the cell From a higher concentration to a lower concentration. Fresh water plants often exist in hypotonic solutions. As water moves into their cells, the cell swells and increases in internal pressure, called turgor pressure.

Turgor Pressure The force of the cell contents pushing against the cell wall. Excess water entering a plant is stored in a large vacuole. This pressure in the cell pushes against the cell wall causing the cell to become stiff and rigid.

Hypotonic Solution Animal cells do not have a cell wall, therefore, as water flows into the cell until it bursts. Animal cells have developed a way to remove excess water. Animal cells use their vacuoles remove water from the cell.

Hypertonic Solution The concentration of water in the cell is lower then the surrounding solution. The result; Cells shrivel up and loose its shape because more water flows out of the cell then into the cell.

Living Cells – Concentration Gradients Hypotonic Isotonic Hypertonic Lower outside the cell Equal outside the cell Greater outside the cell Greater inside the cell Equal inside the cell Lower inside the cell. Cell contents swell Cell contents stay the same Cell contents shrink

Homeostasis The ability of an organism to maintain a constant internal balance even when the conditions around it change.

Passive Transport The movement of molecules through the cell membrane without using energy.

Active Transport The movement of molecules from areas of lower concentration to areas of higher concentration with the use of energy.

Endocytosis Cell membrane encloses a substance or particle, forming a pouch. The pouch is drawn into the cell. Then pinched free of the cell membrane.

Exocytosis Reverse of Endocytosis Substances to be removed from the cell are enclosed in a vacuole Vacuole moves to the cell membrane and fuses The content of the vacuole are then expelled from the cell.