Unit 6: Cellular Transport

Unit 6 Table of Contents Lesson 6.1 – Concentration Gradients Lesson 6.2 – Active vs. Passive Transport Lesson 6.3 – Diffusion Lesson 6.4 – Osmosis Lesson 6.5 – Active Transport

Lesson 6.1 Concentration Gradients Learning Objectives I can explain the concept of a concentration gradient, and identify the direction of movement along (with) a concentration gradient.

Molecules are always moving Molecules move randomly and bump into each other and other barriers

Collision Theory The more molecules are crowded together, in one place, the more they collide (bump into each other). As they collide, they spread out. More collisions = more energy = higher temperatures Fewer collisions = less energy = lower temperature

Concentration gradient Concentration Gradient - change in the concentration of a substance from one area to another. Moving “with the concentration gradient” means moving from HIGH to LOW concentration.

Lesson 6.2 Cellular Transport Learning Objectives I can explain the difference between active and passive transport.

Cellular Transport In order for cells to survive, they must be able to: Move in materials which they need (nutrients, oxygen, water) Move out materials that accumulate as toxic wastes (carbon dioxide and nitrogenous wastes) as well as chemicals made by the cell (secretion)

Two Types of Cellular Transport Passive Transport: moves materials with the concentration gradient. Requires no energy be used by the cell. (Diffusion, Facilitated Diffusion, and Osmosis) Active Transport: requires the cell to use energy (ATP) moves materials against the concentration gradient or materials that are too large to diffuse through the cell membrane.

Two Types of Cellular Transport

Active vs. Passive Transport DRAW this Venn diagram in your notebook. Make it nice and big (about half a page).

Active vs. Passive Transport

Active vs. Passive Transport

Active vs. Passive Transport

Active vs. Passive Transport

Lesson 6.3 Diffusion Learning Objectives I can explain what a semi-permeable membrane is. I can explain the process of diffusion and predict the direction of movement of particles in an experiment or diagram. I can how diffusion is affected by environmental conditions such as temperature, size of particles, and concentration gradients.

Diffusion Molecules in solution tend to slowly spread apart over time. This is diffusion. It is passive transport.

Diffusion is… movement of molecules from an area of high concentration to an area of lower concentration. (“spreading out”)

Diffusion will continue until equilibrium is reached. Equilibrium means there will be an equal distribution of molecules throughout the space. Solute: the substance being dissolved. (Ex: Sugar) Solvent: the substance doing the dissolving. (Ex: Water) This is why food coloring moves throughout a beaker of water; why odors smell strong at first and then disappear over time.

Which direction will the molecules diffuse in each of the figures below? 1 2 3 4 5 6

ANSWERS 1 2 3 4 No Movement 5 6 No Movement

Facilitated Diffusion Uses transport/channel proteins for diffusion Particles always move with a concentration gradient. Passive transport. Usually for specific molecules such as glucose. Facilitated diffusion stops at equilibrium.

Lesson 6.3 Diffusion Learning Objectives I can explain what a semi-permeable membrane is. I can explain the process of diffusion and predict the direction of movement of particles in an experiment or diagram. I can how diffusion is affected by environmental conditions such as temperature, size of particles, and concentration gradients.

Diffusion Across Selectively Permeable Membranes The membrane is “selectively permeable”, meaning: Not all molecules can diffuse through the cell membrane Small molecules, like O2, CO2, and H2O CAN diffuse easily through the cell membrane.

Passive Transport: Diffusion Across a Selectively Permeable Membrane Why is the red solute not diffusing from the right to the left side? It’s too large to pass through the membrane!

Lesson 6.3 Diffusion Learning Objectives I can explain what a semi-permeable membrane is. I can explain the process of diffusion and predict the direction of movement of particles in an experiment or diagram. I can how diffusion is affected by environmental conditions such as temperature, size of particles, and concentration gradients.

Factors Which Affect the Rate of Diffusion: Temperature: Higher the temperature, the higher the energy of the particles, resulting in more collisions, resulting in a higher rate of diffusion. Concentration of Substance: The more substance present, the more collisions occur, resulting in a faster rate of diffusion. Size of Particle: The higher the molecular or atomic mass the lower the rate of diffusion, the lower the molecular mass the faster the rate of diffusion.

Passive Transport

Amoeba Sisters Video: Cellular Transport

Lesson 6.4 Osmosis Learning Objectives I can explain the process of osmosis. I can identify hypertonic, hypotonic, and isotonic solutions, and be able to predict the direction of water movement across a semipermeable membrane.

Amoeba Sisters Video: Osmosis

Osmosis Osmosis is the movement of WATER across a semi-permeable membrane.

Osmosis Look at the diagram below: At first the concentration of solute is very high on the right. But over time, the water moves across the semi-permeable membrane and dilutes the particles.

Hypotonic = lower concentration of solute (high water) Hypertonic = higher concentration of solute (low water)

Osmosis: Solutions Isotonic = equal concentrations of solute & water on each side

Osmosis: Solutions

As viewed under the microscope ELODEA CELLS As viewed under the microscope

Lesson 6.5 Active Transport I can explain the difference between active and passive transport I can explain the process of exocytosis in cells. I can explain the process of endocytosis (including phagocytosis and pinocytosis) in cells.

Active Transport: Active transport requires the use of energy (ATP ) by the cell to move materials in or out. Active transport is used when: Moving materials against the concentration gradient Moving ions of the same charge together Moving large molecules

Active Transport: Proton Pump

Active Transport

Lesson 6.5 Active Transport I can explain the difference between active and passive transport I can explain the process of exocytosis in cells. I can explain the process of endocytosis (including phagocytosis and pinocytosis) in cells.

Active Transport: Exocytosis Exocytosis is the movement of materials out of the cell for secretion or to get rid of cellular waste. It is the reverse of phagocytosis or endocytosis.

Lesson 6.5 Active Transport I can explain the difference between active and passive transport I can explain the process of exocytosis in cells. I can explain the process of endocytosis (including phagocytosis and pinocytosis) in cells.

Active Transport: Endocytosis Endocytosis is the process of taking materials into the cell that are: too large to pass through the cell membrane (phagocytosis), liquids that can not diffuse through the membrane (pinocytosis)

Active Transport: Endocytosis

EXO and ENDO

Additional Practice for Osmotic Solutions

Osmosis Animations for isotonic, hypertonic, and hypotonic solutions Hypotonic: The solution has a lower concentration of solutes and a higher concentration of water than inside the cell. (Low solute; High water) Result: Water moves from the solution to inside the cell): Cell Swells and bursts open (cytolysis)!

Osmosis Animations for isotonic, hypertonic, and hypotonic solutions Hypertonic Solution Hypertonic: The solution has a higher concentration of solutes and a lower concentration of water than inside the cell. (High solute; Low water) shrinks Result: Water moves from inside the cell into the solution: Cell shrinks (Plasmolysis)!

Osmosis Animations for isotonic, hypertonic, and hypotonic solutions Isotonic Solution Isotonic: The concentration of solutes in the solution is equal to the concentration of solutes inside the cell. Result: Water moves equally in both directions and the cell remains same size! (Dynamic Equilibrium)

B C A What type of solution are these cells in? Hypertonic Isotonic Hypotonic

How Organisms Deal with Osmotic Pressure Paramecium (protist) removing excess water video Bacteria and plants have cell walls that prevent them from over-expanding. In plants the pressure exerted on the cell wall is called tugor pressure. A protist like paramecium has contractile vacuoles that collect water flowing in and pump it out to prevent them from over-expanding. Salt water fish pump salt out of their specialized gills so they do not dehydrate. Animal cells are bathed in blood. Kidneys keep the blood isotonic by remove excess salt and water.