Section 4: Diffusion and Osmosis Chapter 3: Cells Section 4: Diffusion and Osmosis Chapter 3: Cells Section 4: Diffusion and Osmosis

Body Spray Graphing Activity Passive Transport Presentation Chapter 3: Cells Section 4: Diffusion and Osmosis Agenda Do Now! Body Spray Graphing Activity Passive Transport Presentation

Chapter 3: Cells Section 4: Diffusion and Osmosis Do Now! Think about the graphs you have made in the past. In your Biology notebook, write down as many characteristics of a good line graph as you can think of.

What kind of energy is represented by this motion? Chapter 3: Cells Section 4: Diffusion and Osmosis Molecules move randomly What kind of energy is represented by this motion? In all matter, molecules are always moving randomly and bumping in to each other.

“diffuse” means “spread out” or “to spread out” Chapter 3: Cells Section 4: Diffusion and Osmosis Diffusion Diffusion is the movement of molecules in a fluid or gas from a region of higher concentration to a region of lower concentration “diffuse” means “spread out” or “to spread out”

Chapter 3: Cells Section 4: Diffusion and Osmosis

Is a type of passive transport Chapter 3: Cells Section 4: Diffusion and Osmosis Diffusion Is a type of passive transport Passive transport uses no energy to move molecules “Passive” means “not participating readily or activ- ely”

Chapter 3: Cells Section 4: Diffusion and Osmosis “Diffusion”

Chapter 3: Cells Low concentration Equal concentration Section 4: Diffusion and Osmosis Low concentration Equal concentration High concentration

Chapter 3: Cells “Diffusion of Food Coloring in a Water Solution” Section 4: Diffusion and Osmosis “Diffusion of Food Coloring in a Water Solution”

Molecules move “down” a concentration gradient Chapter 3: Cells Section 4: Diffusion and Osmosis Concentration Gradient A concentration gradient is the difference in the concentration of a substance from one region to another. Molecules move “down” a concentration gradient

Chapter 3: Cells Section 4: Diffusion and Osmosis

Chapter 3: Cells Section 4: Diffusion and Osmosis learn

Osmosis Osmosis is diffusion across a semi-permeable membrane. Chapter 3: Cells Section 4: Diffusion and Osmosis Osmosis Osmosis is diffusion across a semi-permeable membrane. Because it is a type of diffusion, osmosis is also passive transport Osmosis is critical to the health of cells

Chapter 3: Cells Section 4: Diffusion and Osmosis "Osmosis"

Check for Understanding: How many fingers? Chapter 3: Cells Section 4: Diffusion and Osmosis Check for Understanding: How many fingers?

Solutions with a Membrane Chapter 3: Cells Section 4: Diffusion and Osmosis Solutions with a Membrane The concentration of a solute may be different on one side of a membrane than the other. The words isotonic, hypertonic, and hypotonic help us to compare these two environments. “iso” = “same” “hyper” = “more” “hypo” = “less”

Solutions with a Membrane Chapter 3: Cells Section 4: Diffusion and Osmosis Solutions with a Membrane An Isotonic solution has the same amount of solute on both sides of the membrane or cell. A Hypertonic solution has more solute than inside the membrane or cell. A Hypotonic solution has less solute than inside the membrane or cell.

Chapter 3: Cells Section 4: Diffusion and Osmosis “same” “more” “less”

Facilitated Diffusion Chapter 3: Cells Section 4: Diffusion and Osmosis Facilitated Diffusion Facilitated diffusion is a special case of osmosis. Molecules that are too big and/or too polar need help to cross the cell membrane! Molecules that cannot normally cross the cell membrane may be helped across by transport channel proteins

Chapter 3: Cells Section 4: Diffusion and Osmosis

Chapter 3: Cells Section 4: Diffusion and Osmosis