BIO U4:L2 Cell's Transport Mechanism I: Diffusion and Osmosis PDF

Lesson 4.2 Cell’s Transport Mechanism I: Diffusion and Osmosis General Biology 11/2 Science, Technology, Engineering, and Mathematics Water is a very essential substance for life to persist. 2  When a plant is not watered for days, it wilts because its cells lack s...

Lesson 4.2 Cell’s Transport Mechanism I: Diffusion and Osmosis General Biology 11/2 Science, Technology, Engineering, and Mathematics Water is a very essential substance for life to persist. 2  When a plant is not watered for days, it wilts because its cells lack sufficient water. Animals drink water not just to quench thirst when feeling hot, but also to help cells in performing daily biochemical processes. 3 Water has various properties that help sustain life. 4 How do water molecules cross the membrane? 5 Learning Competency At the end of the lesson, you should be able to do the following: Explain the transport mechanisms in cells (diffusion and osmosis) (STEM_BIO11/12-Ig-h-13). 6  Learning Objectives At the end of the lesson, you should be able to do the following: Explain the difference between diffusion and osmosis as molecules cross the membrane. Differentiate hypotonic, isotonic and hypertonic solutions for animal and plant cells. 7 How does diffusion affect the movement of substances into and out of the cell? 8  Cell’s Transport Mechanism I D Simple Diffusion Facilitated Diffusion I F Area of higher F concentration U S I O N 9  Cell’s Transport Mechanism I D Simple Diffusion Facilitated Diffusion I F Equilibrium is F achieved U S I O N 10  Cell’s Transport Mechanism I D Simple Diffusion Facilitated Diffusion I F F U S I O Diffusion involves the movement of molecules in a solvent from an area of N higher solute concentration to an area of lower solute concentration which eventually results in the state of dynamic equilibrium. 11  Cell’s Transport Mechanism I D Simple Diffusion Facilitated Diffusion I F F U S no energy high to low I required concentration O passive movement of state of dynamic N transport molecules equilibrium 12  Cell’s Transport Mechanism I D Simple Diffusion Facilitated Diffusion I F F Molecules such as ions and water U outside the cell are being S transported across the cell membrane through channel I proteins via facilitated diffusion. O N 13  Cell’s Transport Mechanism I D Simple Diffusion Facilitated Diffusion I F The channel protein facilitates F the movement of molecules U hence the term “facilitated diffusion”. S I O N 14 How does osmosis play an important role in different cellular processes? 15  Cell’s Transport Mechanism I Isotonic Hypotonic Hypertonic O S Semi-permeable M membrane O S I Low water, High S High water, low solute solute concentration concentration 16  Cell’s Transport Mechanism I Isotonic Hypotonic Hypertonic O S M Movement is from the region of high O water concentration to S one with lower water I concentration. S 17  Cell’s Transport Mechanism I Isotonic Hypotonic Hypertonic O S M Osmosis is similar to diffusion. O However, osmosis refers to the S movement of water from higher to I lower concentration. S 18  Cell’s Transport Mechanism I Isotonic Hypotonic Hypertonic O S relative concentration ability of a surrounding solution to cause a cell of solutes in fluids M to gain or lose water O S Tonicity I depends on the can be isotonic, S concentration of hypotonic, or solutes hypertonic 19  Cell’s Transport Mechanism I Isotonic Hypotonic Hypertonic O S solute solute M molecules molecules O outside the cell inside the cell S I Isotonic solution Solutions of equal solute S concentration 20  Cell’s Transport Mechanism I Isotonic Hypotonic Hypertonic O S Isotonic solution M is when water O molecules move at the S same rate in both directions. I S 21  Cell’s Transport Mechanism I Isotonic Hypotonic Hypertonic O S solute solute M molecules molecules O outside the cell inside the cell S I Hypotonic solution has lower solute concentration and S has higher water concentration (i.e., less solute, more water). 22  Cell’s Transport Mechanism I Isotonic Hypotonic Hypertonic O S M Hypotonic solution O can cause the cell to swell or even burst due S to the intake of water I more than the cell can S accommodate. 23  Cell’s Transport Mechanism I Isotonic Hypotonic Hypertonic O S solute solute M molecules molecules O outside the cell inside the cell S I Hypertonic solution has higher solute concentration S and has lower water concentration (i.e., more solute, less water). 24  Cell’s Transport Mechanism I Isotonic Hypotonic Hypertonic O S M Hypertonic solution can cause an animal O cell to shrink or shrivel S due to water loss. I S 25  Cell’s Transport Mechanism I Isotonic Hypotonic Hypertonic O S M O S I S Plant cells, relative to animal cells, do not change cell size that much with varying concentrations of water. 26 Marine fishes and other types of animals drink water but excrete salts across their gills. Why do they do this? 27  Check Your Understanding Identify the correct term being described in each of the following statements. 1. It refers to the relative concentration of solutes in fluids separated by a selectively permeable membrane. 2. It refers to a solution where water is drawn out of the cell. 3. It is one of the components of a homogeneous mixture that is usually solid. 28  Check Your Understanding Classify the following situations based on the tonicity of the surrounding environment. Write if it is isotonic, hypotonic, or hypertonic. 1. It can be observed that plants wilt and are almost dying along a salted roadside. 2. Paramecia live in freshwater environments and use their contractile vacuoles to get rid of excess water. 29  Check Your Understanding Classify the following situations based on the tonicity of the surrounding environment. Write if it is isotonic, hypotonic, or hypertonic. 3. Some animals must drink the saltwater to get the water into their bodies, but they maintain it by making the salts concentrated and excreted from the body. 30  Let’s Sum It Up! Diffusion is the movement of molecules down their concentration gradient, i.e., from an area of higher concentration to an area of lower concentration. A solution contains both the solute, which is usually solid and a solvent, which is usually a liquid. A solute added in a solvent will naturally diffuse to form a solution. 31  Let’s Sum It Up! Diffusion is an example of passive transport in which molecules are moved across the membrane without spending energy. Facilitated diffusion involves the movement of molecules across the membrane but with the aid of either channel or carrier proteins. These molecules are usually those that cannot cross due to their molecular size or chemical nature. 32  Let’s Sum It Up! Osmosis is the diffusion of water across a selectively permeable membrane from high to low concentration. ○ Solutions with an equal solute concentration are said to be isotonic. ○ Hypotonic solution has a lower concentration of solutes than inside the cell. ○ Hypertonic solution is one with a higher concentration of solute outside of the membrane. 33  Let’s Sum It Up! Diffusion and osmosis both involve movement of molecules without spending energy. 34 Challenge Yourself You took a fresh sample of human blood and observed it under the microscope. You added a solution that your laboratory technician gave you. To your surprise, the specimen becomes clear and void of cells. What could have happened to the cells? 35  Photo Credit Bibliography Hoefnagels, Marielle. Biology: The Essentials. 2nd ed. McGraw-Hill Education, 2016. Mader, Sylvia S., and Michael Windelspecht. Biology. 11th ed. McGraw-Hill Education, 2014. Slide 1: Rhizomnium punctatum lamina by Kristian Peters -- Fabelfroh 09:12, 28 February 2007 (UTC) is Reece, Jane B, Martha R. Taylor, Eric J. Simon, Jean L. Dickey, licensed under CC BY-SA 3.0 via Wikimedia Commons. and Kelly Hogan. Biology Concepts and Connections. 8th ed. Pearson Education South Asia Pte Ltd., 2016. Simon, Eric J., and Jane B. Reece. Campbell Essential Biology. 5th ed. Pearson Education Inc., 2013. Starr, Cecie, Christine A. Evers, and Lisa Starr. Biology Today and Tomorrow. 4th ed. Cengage Learning Asia Pte Ltd, 2014. 36