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Cellular Physiology: Membrane Transport Membrane Transport is the movement of substance into and out of the cell Transport is by two basic methods Passive transport No energy is required Active transport The cell must provide metabolic energy Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Solutions and Transport Solution – homogeneous mixture of two or more components Solvent – dissolving medium (liquid) Solutes – components in smaller quantities within a solution (“stuff”) Intracellular fluid - fluid inside the cell nucleoplasm and cytosol Interstitial fluid – fluid on the exterior of the cell, between cells Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Tonicity - is the degree to which a solution’s concentration of solute versus water (solvent) causes water to move into or out of a cell Solute Solvent Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Selective Permeability Membranes are selectively permeable The plasma membrane allows some materials to pass while excluding others This permeability includes movement into and out of the cell Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Passive Transport Processes Diffusion Does NOT require ATP Particles tend to distribute themselves evenly within a solution Movement is from high concentration to low concentration, or down a concentration gradient how_diffusion_works.h tml Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 3.9 Passive Transport Processes Types of diffusion 1. Simple diffusion 2. Osmosis 3. Facilitated diffusion 1. Simple diffusion Unassisted process No ATP required Solutes are lipid-soluble materials or small enough to pass through membrane pores Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Passive Transport Processes Types of diffusion 2. Osmosis – simple diffusion of water Highly polar water crosses the plasma membrane through aquaporins 3. Facilitated diffusion Substances require a protein carrier for passive transport how_facilitated_diffusio n_works.html how_osmosis_works.html Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Diffusion through the Plasma Membrane Flows from High Concentration to a Low concentration Figure 3.10 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Active Transport Processes Active Transport requires ATP Transport substances that are unable to pass by diffusion They may be too large They may not be able to dissolve in the fat core of the membrane They may have to move against a concentration gradient Two common forms of active transport Solute pumping Bulk transport Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Active Transport Processes Solute pumping Amino acids, some sugars and ions are transported by solute pumps ATP energizes protein carriers, and in most cases, moves substances against concentration gradients Videopump Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Active Transport Processes Sodium Potassium Pump Figure 3.11 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Review Slide – DO NOW 1. How is passive transport different from active transport? 2. If I make Iced Tea from a sugary powdered mix and water, which is the solvent and which is solute? 3. Where would you find interstitial fluid in your body? 4. What does selectively permeable mean? 5. What is the main difference between simple diffusion and facilitated diffusion 6. Why is solute pumping considered a form of active transport? Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Active Transport Processes Bulk transport Exocytosis - Moves materials out of the cell Material is carried in a membranous vesicle Vesicle migrates to plasma membrane Vesicle combines with plasma membrane Material is emptied to the outside Requires ATP Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Exocytosis Figure 3.12a Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Active Transport Processes Bulk transport Endocytosis - Substances into the cell Extracellular substances are engulfed by being enclosed in a membranous vescicle Types of endocytosis Phagocytosis – cell eating phagocytosis.html Pinocytosis – cell drinking Pinocytosis and Phagocytosis Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Endocytosis Figure 3.13a Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Review Slide What is the difference between a solute and a solvent? How is Passive transport different from Active transport? Intracellular fluid vs. Interstitial Fluid? List and Describe the Types of Passive transport - Give an example of each Compare and contrast endocytosis and exocytosis Why do cells need to divide? Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Where does mitosis occur in your body? Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Cell Life Cycle Cells have two major periods to its Life cycle Interphase how_the_cell_cycle_works.html Cell grows Cell carries on metabolic processes Cell division (Mitosis) Cell replicates itself Function is to produce more cells for growth and repair processes Mitosis: An Interactive Animation Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Animation: Mitosis and Cytokinesis control_of _the_cell _cycle.ht ml Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Cell Cycle Living cells go through a series of stages known as the cell cycle. The cells grow, copy their chromosomes, and then divide to form new cells. G1 phase. The cell grows. S phase. The cell makes copies of its chromosomes. Each chromosome now consists of two sister chromatids G2 phase. The cell checks the duplicated chromosomes and gets ready to divide. M phase. The cell separates the copied chromosomes to form two full sets (mitosis) and the cell divides into two new cells (cytokinesis). The period between cell divisions is known as ‘Interphase'. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings m Mitosis is used to produce daughter cells that are genetically identical to the parent cells. mitosis_and_cytokinesis.ht ml Meiosis is used to make special cells sperm cells and egg cells - that have half the normal number of chromosomes. It reduces the number from 23 pairs of chromosomes to 23 single chromosomes. Meiosis Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings DNA Replication to prepare for Mitosis DNA is duplicated to prepare the cell for division Occurs toward the end of interphase during the “S phase” DNA uncoils and each side serves as a template Figure 3.14 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Part I - Mitosis Division of the nucleus Results in the formation of two daughter nuclei Part II - Cytokinesis Division of the cytoplasm Results in the formation of two identical daughter cells Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Stages of Mitosis Stages of Mitosis Interphase – Has phases – G1, S G2 No cell division occurs The cell carries out normal metabolic activity and growth and prepares for division Prophase First part of cell division Centrioles migrate to the poles Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Stages of Mitosis Metaphase Spindle from centrioles are attached to chromosomes that are aligned in the center of the cell Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Stages of Mitosis Anaphase Daughter chromosomes are pulled toward the poles The cell begins to elongate Telophase Daughter nuclei begin forming A cleavage furrow (for cell division) begins to form Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Stages of Mitosis Figure 3.15 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Stages of Mitosis Figure 3.15(cont) Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Mitosis Lab Mitosis in Plant Cells Objective: to observe the stages of mitosis in plant cells Materials: onion root tip slide Procedure: 1. Observe the onion root tip in low power and high power. 2. Locate four cells in four different stages of mitosis 3. Draw and label each of the four stages in high power Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Conclusion: 1. Describe how you recognized a cell in prophase. 2. Where are the chromosomes located in metaphase? 3. What is happening in anaphase? 4. Describe how the 2 daughter cells compare to the parent cell. 5. Describe how the 2 daughter cells compare to EACH OTHER. 6. What is mitosis? 7. What kind of cells go through mitosis? Give two examples Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Prophase? Metaphase? Anaphase? Telophase? 1 3 2 4 5 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings 6 Prophase? Metaphase? Anaphase? Telophase? Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Prophase? Metaphase? Anaphase? Telophase? 1 2 5 3 6 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings 4 7