* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Chapter 5 Section 1 Passive Transport
Survey
Document related concepts
Extracellular matrix wikipedia , lookup
Cytoplasmic streaming wikipedia , lookup
Cellular differentiation wikipedia , lookup
Cell culture wikipedia , lookup
Cell growth wikipedia , lookup
Cell encapsulation wikipedia , lookup
Magnesium transporter wikipedia , lookup
Membrane potential wikipedia , lookup
Signal transduction wikipedia , lookup
Cytokinesis wikipedia , lookup
Organ-on-a-chip wikipedia , lookup
Cell membrane wikipedia , lookup
Transcript
Chapter 5 Homeostasis and Cell Transport Table of Contents Section 1 Passive Transport Section 2 Active Transport Chapter 5 Section 1 Passive Transport Objectives • Explain how an equilibrium is established as a result of diffusion. • Distinguish between diffusion and osmosis. • Explain how substances cross the cell membrane through facilitated diffusion. • Explain how ion channels assist the diffusion of ions across the cell membrane. Chapter 5 Section 1 Passive Transport Standards SPI 3210.1.7 Predict the movement of water and other molecules across selectively permeable membranes. SPI 3210.1.8 Compare and contrast active and passive transport. 3210.1.8 Analyze experimental data to distinguish between active and passive transport. CLE 3210.1.5 Compare different models to explain the movement of materials into and out of cells. Chapter 5 Section 1 Passive Transport Passive Transport •Involves the movement of molecules across the cell membrane •without an input of energy by the cell. • NO ENERGY REQUIRED to move substances across membrane -- water, lipids, and other lipid soluble substances. • Types: – Diffusion – Osmosis – Facilitated Diffusion – Filtration Chapter 5 Section 1 Passive Transport Diffusion • Diffusion is the movement of molecules from an area of higher concentration to an area of lower concentration, driven by the molecules’ kinetic energy until a state of dynamic equilibrium* is reached. – Concentration gradient, i.e., the difference in concentration across space. • Occurs because of Brownian Motion, i.e., the random movement of particles. *Dynamic equilibrium – continued movement of molecules with no net change in concentration Chapter 5 Section 1 Passive Transport Concentration Gradient Click below to watch the Visual Concept. Chapter 5 Diffusion Section 1 Passive Transport Chapter 5 Osmosis • Osmosis is the diffusion of water across a membrane. Section 1 Passive Transport Chapter 5 Section 1 Passive Transport Osmosis Click below to watch the Visual Concept. Chapter 5 Section 1 Passive Transport Osmosis, continued • Direction of Osmosis – The net direction of osmosis is determined by the relative solute concentrations on the two sides of the membrane. Chapter 5 Section 1 Passive Transport Osmosis, continued • Direction of Osmosis – When the solute concentration outside the cell is higher than that in the cytoplasm, the solution outside is hypertonic (more solute, less water) to the cytoplasm, and water will diffuse out of the cell. – Plasmolysis = cell’s shrinking due to water loss Chapter 5 Section 1 Passive Transport Osmosis, continued • Direction of Osmosis – When the solute concentration outside the cell is lower than that in the cytosol, the solution outside is hypotonic (less solute, more water) to the cytosol, and water will diffuse into the cell. – Cytolysis = cell’s bursting due to water gain Chapter 5 Section 1 Passive Transport Osmosis, continued • Direction of Osmosis – When the solute concentrations outside and inside the cell are equal, the solution outside is isotonic (same solute, same water), and there will be no net movement of water. Chapter 5 Section 1 Passive Transport Hypertonic, Hypotonic, Isotonic Solutions Chapter 5 Section 1 Passive Transport Osmosis, continued • How Cells Deal With Osmosis – To remain alive, cells must compensate for the water that enters the cell in hypotonic environments and leaves the cell in hypertonic environments. – Cells in multicellular organisms respond to hypotonic environments by pumping solutes out of the cytosol (RBCs cannot compensate for changes in solute concentration) – Contractile vacuoles are organelles that regulate water levels in paramecia. Chapter 5 Section 1 Passive Transport Facilitated Diffusion • Diffusion of molecules across a membrane when they are not soluble in lipids or are too large (e.g. glucose) to pass through pores in membrane • In facilitated diffusion, a molecule binds to a carrier protein on one side of the cell membrane. • The carrier protein (specific for one type of molecule) then changes its shape and transports the molecule down its concentration gradient to the other side of the membrane. Chapter 5 Section 1 Passive Transport Facilitated Diffusion Chapter 5 Section 1 Passive Transport Diffusion Through Ion Channels • Ion channels are proteins, or groups of proteins, that provide small passageways across the cell membrane through which specific ions can diffuse. • Ions important in cell function include sodium, potassium, calcium, and chloride Chapter 5 Ion Channels Section 1 Passive Transport Chapter 5 Section 2 Active Transport Crash Course #5 Cell Membranes and Transport Chapter 5 Section 2 Active Transport Objectives • Distinguish between passive transport and active transport. • Explain how the sodium-potassium pump operates. • Compare endocytosis and exocytosis. Chapter 5 Section 1 Passive Transport Standards SPI 3210.1.7 Predict the movement of water and other molecules across selectively permeable membranes. SPI 3210.1.8 Compare and contrast active and passive transport. 3210.1.8 Analyze experimental data to distinguish between active and passive transport. CLE 3210.1.5 Compare different models to explain the movement of materials into and out of cells. Chapter 5 Section 2 Active Transport Cell Membrane Pumps • Active transport moves molecules across the cell membrane from an area of lower concentration to an area of higher concentration. • Unlike passive transport, active transport requires cells to expend energy. • Some types of active transport are performed by carrier proteins called cell membrane pumps. Chapter 5 Section 2 Active Transport Cell Membrane Pumps, continued • Sodium-Potassium Pump – The sodium-potassium pump moves three Na+ ions into the cell’s external environment for every two K+ ions it moves into the cytoplasm. • Animal cells must have a higher concentration of Na+ ions outside the cell and a higher concentration of K+ ions inside the cell – ATP supplies the energy that drives the pump. Chapter 5 Section 2 Active Transport Sodium-Potassium Pump Chapter 5 Section 2 Active Transport Sodium-Potassium Pump • The exchange of three Na+ ions for two K+ ions creates an electrical gradient across the cell membrane – Outside becomes positively charged relative to the inside, which becomes negative • Difference in electrical charge is important for the conduction of electrical impulses along nerve cells Chapter 5 Section 2 Active Transport Movement in Vesicles • Endocytosis – In endocytosis, cells ingest external fluid, macromolecules, and large particles, including cells by folding around them and forming a pouch. – The pouch then pinches off and becomes a membrane-bound organelle called a vesicle. *Some vesicles fuse with lysosomes, and their contents are digested by lysosomal enzymes Chapter 5 Section 2 Active Transport Movement in Vesicles, continued • Endocytosis – Endocytosis includes pinocytosis, in which the vesicle contains solutes or fluids, and phagocytosis, in which the vesicle contains large particles or whole cells. • Bacteria and viruses are ingested in this way – Receptor-mediated endocytosis – molecules are brought into the cell via coated pits (proteins) Chapter 5 Section 2 Active Transport Movement in Vesicles, continued • Exocytosis – In exocytosis, vesicles made by the cell fuse with the cell membrane, releasing their contents into the external environment. • Used to release large molecules, such as proteins, waste products, or toxins that would damage the cell if they were released within the cytoplasm Chapter 5 Section 2 Active Transport Exocytosis and Endocytosis Click below to watch the Visual Concept. Visual Concept Chapter 5 Section 2 Active Transport Endocytosis and Exocytosis