BIO U4:L3 Cell's Transport PDF

Lesson 4.3 Cell’s Transport Mechanism II: Active and Facilitated Transport General Biology 11/2 Science, Technology, Engineering, and Mathematics Imagine how hard it is for a salmon to swim upstream during spawning season. 2  For the case of the cell, it is also a work t...

Lesson 4.3 Cell’s Transport Mechanism II: Active and Facilitated Transport General Biology 11/2 Science, Technology, Engineering, and Mathematics Imagine how hard it is for a salmon to swim upstream during spawning season. 2  For the case of the cell, it is also a work to do to drive the movement of molecules against the concentration gradient. 3 Why is there a need to transport substances against the concentration gradient? 4 Learning Competency At the end of the lesson, you should be able to do the following: Explain the transport mechanisms in cells (facilitated transport, and active transport) (STEM BIO11/12-Ig-h-13). 5  Learning Objectives At the end of the lesson, you should be able to do the following: Explain how active transport moves substances across a membrane. Compare the movement of active transport from osmosis and diffusion. Explain how molecules are being transported across the membrane through facilitated transport. 6 How does the structure of the cell membrane help in its function to transport substances? 7  Cell’s Transport Mechanism II It is a cellular transport mechanism that A involves the movement of molecules against C their concentration gradient with energy T expenditure. I V It allows cells to maintain internal E concentrations of small solutes that significantly differ from environmental Transport concentrations. 8  Cell’s Transport Mechanism II A C Cells that perform active transport have a T relatively large number of mitochondria. This I is very evident and important in muscle cells V and nerve cells of the body. E Transport 9  Cell’s Transport Mechanism II A C T I V E Transport Molecules outside the cell going against the concentration gradient (from low to high concentration). 10  Cell’s Transport Mechanism II Sodium-Potassium Pump Calcium Pump A C T I V E Transport The sodium-potassium carrier protein has an initial shape that allows it to bind three sodium ions. 11  Cell’s Transport Mechanism II Sodium-Potassium Pump Calcium Pump A C T I V E Transport Phosphate from an ATP molecule is added to the carrier protein, and it changes shape which allows the movement of sodium ions across the membrane. 12  Cell’s Transport Mechanism II Sodium-Potassium Pump Calcium Pump A C T I V E Transport The new shape is compatible with picking up two potassium ions, which bind to their respective sites. 13  Cell’s Transport Mechanism II Sodium-Potassium Pump Calcium Pump A C T I V E Transport As the phosphate that was added from ATP previously leaves, the carrier protein assumes its original shape, and the two potassium ions are released inside the cell. 14 What could be the effect on the nerve cells if the sodium-potassium pump failed to function? 15  Cell’s Transport Mechanism II Sodium-Potassium Pump Calcium Pump A C T I V Calcium ions must be maintained E at low concentrations inside the cell. This is essential for the proteins in cells to function normally. Transport 16  Cell’s Transport Mechanism II Sodium-Potassium Pump Calcium Pump A C T I V Calcium pumps do not need E binding to a second ion for the protein pump to return to its original shape. It simply binds to the calcium ions and pumps them Transport out of the cell. 17  Cell’s Transport Mechanism II F A It involves the movement of molecules down C their concentration gradient, but with the aid I of membrane transport proteins. L I T The transport proteins can only transport a A certain type of molecule or ion across the T membrane. They can either be carrier E D proteins (also called transporters) or channel proteins. Transport 18  Cell’s Transport Mechanism II F Glucose Transporters Ion Channels A C I L I T A T E D Glucose transporters are carrier proteins that transport glucose Transport down their concentration gradient. 19  Cell’s Transport Mechanism II F Glucose Transporters Ion Channels A C I L I T A T E D The glucose binds to the glucose transporter. Transport 20  Cell’s Transport Mechanism II F Glucose Transporters Ion Channels A C I L I T A T E D A change in the conformation of the carrier protein or transporter Transport transports glucose across the membrane. 21  Cell’s Transport Mechanism II F Glucose Transporters Ion Channels A C I Ion channels are very specific because they only L I allow the passage of certain ions. T A Note that the cell maintains relatively different T concentrations of ions inside and outside the E D cell. Transport 22  Cell’s Transport Mechanism II F Glucose Transporters Ion Channels A C I Na+ is abundant outside, while K+ is more L abundant inside the cell. I ○ To balance these charges, the cell also T A maintains a relatively high Cl− outside the cell T (alongside sodium ions) and a relatively E higher concentration of organic and inorganic D ions or anions (alongside potassium ions). Transport 23  Cell’s Transport Mechanism II F Glucose Transporters Ion Channels A C I L I T A T E D Ion channels are usually gated. They will open Transport when certain conditions are met. 24  Cell’s Transport Mechanism II F Glucose Transporters Ion Channels A C I L The sodium-potassium pump helps restore the I concentration of sodium and potassium ions T A outside and inside the cell, respectively. As T mentioned, these channels are not normally E open, thus they are said to be gated. D Transport 25 Remember How does active and facilitated transport differ from each other? Active transport involves the movement of molecules or ions against the concentration gradient which requires energy while facilitated transport transfer molecules or ions down the concentration gradient which does not require the use of energy. 26  Check Your Understanding Identify the correct term being described by each of the following statements. 1. These proteins transport certain types of molecules or ions across the membrane. 2. This protein transports glucose molecules from the gut to the intestinal epithelial cell. 3. This protein allows the movement of sodium ions down their concentration gradient. 27  Check Your Understanding Briefly answer the following questions. 1. How are molecules moved across the membrane via active transport? 2. How do molecules cross the plasma membrane through facilitated transport? 3. What is the function of the sodium-potassium pump? Explain. 28  Let’s Sum It Up! Active transport is a mechanism that allows the movement of molecules across the membrane against the concentration gradient. ○ For a certain molecule to be transported against the concentration gradient, it needs a carrier protein and an expenditure of energy. 29  Let’s Sum It Up! Active transport is a mechanism that allows the movement of molecules across the membrane against the concentration gradient. ○ The sodium-potassium pump moves sodium ions (Na+) to the outside of the cell and potassium ions (K+) into the cell. 30  Let’s Sum It Up! Active transport is a mechanism that allows the movement of molecules across the membrane against the concentration gradient. ○ The calcium pumps do not need binding to a second ion for the protein pump to return to its original shape. It simply binds to the calcium ions and pumps them out of the cell. 31  Let’s Sum It Up! Facilitated transport is the movement of molecules or ions down the concentration with the help of membrane transport proteins. ○ Glucose transporters are found at the base of the epithelial cells of the intestines. These are carriers that supply glucose molecules to the underlying tissues and into the bloodstream. 32  Let’s Sum It Up! Facilitated transport is the movement of molecules or ions down the concentration with the help of membrane transport proteins. ○ Ion channels, such as that of sodium, potassium, and chloride ions, are essential in modifying the charge of the cell’s interior. 33 Let’s Sum It Up! Molecules that cannot pass through the bilayer are assisted by membrane proteins. 34 Challenge Yourself Exposure to a mutagen led to the mutation of the Na+-K+ pump, as well as the calcium pumps, in the left arm. What bodily functions could be affected by this event? 35  Photo Credit Bibliography Hoefnagels, Marielle. Biology: The Essentials. 2nd ed. McGraw-Hill Education, 2016. Mader, Sylvia S., and Michael Windelspecht. Biology. 11th ed. Slide 2: Jumping salmon at Murray’s Cauld, by Walter Baxter is licensed under CC BY-SA 2.0 via Geograph. McGraw-Hill Education, 2014. Reece, Jane B, Martha R. Taylor, Eric J. Simon, Jean L. Dickey, 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