Cell Transport Notes For Videos (1) PDF

By Mrs. Hoskins SB1. Obtain, evaluate, and communicate information to analyze the nature of the relationships between structures and functions in living cells. d. Plan and carry out investigations to determine the role of cellular transport (e.g., active, passive, and osmosis) in maintaini...

By Mrs. Hoskins SB1. Obtain, evaluate, and communicate information to analyze the nature of the relationships between structures and functions in living cells. d. Plan and carry out investigations to determine the role of cellular transport (e.g., active, passive, and osmosis) in maintaining homeostasis.  Overview Homeostasis: need of an organism to stay stable by regulating internal conditions. – A dynamic equilibrium is maintained = it isn’t always the same, but things stay within a range. – Organisms constantly take in stimuli and have to respond to them in order to maintain homeostasis. Stimulus = change in environment Response = a change in the organism, as a result of a stimulus  Overview Feedback mechanisms evolved to help maintain homeostasis in organisms as they respond to stimuli. – These mechanisms use the output of a system to signal a change in input so that a system response can be stabilized or amplified. – Can be positive or negative (+) Feedback Mechanisms In a positive feedback loop, the output (or product) of a system intensifies the response. AMPLIFICATION Examples: – Human child birth Hormones  Contractions  Pressure  Release of more hormones  More contractions  More pressure…etc. – Fruit ripening Fruit ripens  Releases ethylene  Signals surrounding fruit to ripen  Neighboring fruit ripen  Release more ethylene…etc.  (-) Feedback Mechanisms In a negative feedback loop, the output (or product) of a system causes a counter response to return to a set point. STABILIZATION Examples: – Human body temperature (thermoregulation) – Water concentration (osmoregulation) – Blood sugar regulation  Cell Membrane Homeostasis is maintained through regulation at the organ system level all the way down to the cellular level. Much of homeostasis on the cellular level is maintained by the cell membrane controlling the movement of things in and out of the cell.  Cell Membrane The cell membrane is selectively permeable = picky about what goes in and out. – CAN pass easily: things that are small, nonpolar, hydrophobic and/or neutral, as well as water – CANNOT pass easily: polar and/or large molecules The transport of materials into and out of the cell is classified as either passive or active.  Cell Transport Passive Transport requires no extra energy by the cell because molecules move from high concentration (squished together) to low concentration (spread out) areas down the concentration gradient. – Ex. Simple diffusion, facilitated diffusion, and osmosis Active Transport requires extra energy (ATP) to be spent to bring materials into the cell or expel materials out of the cell moving from low to high concentration against the concentration gradient. – Ex. Molecular pumps, exocytosis, and endocytosis  Words to Know Solute: what gets dissolved (Ex. Lemonade powder) Solvent: does the dissolving (Ex. Water) Solution: uniform mixture of two or more substances (Ex. Lemonade) Concentration: amount of solute dissolved in solvent – Symbol for abbreviation = [ ] Concentration gradient: Difference in concentration of a substance from one location to another  Passive Transport: Simple Diffusion The spreading out of molecules across a membrane until equilibrium is reached – Equilibrium = equally concentrated on both sides of the membrane Molecules move down a concentration gradient, from high [ ] to an area of low [ ] – Ex. O2 and CO2, and other small, nonpolar molecules Over time…  Passive Transport: Facilitated Diffusion A transport protein helps to facilitate the diffusion of molecules that normally couldn‘t pass through the cell membrane – Transport proteins can act as a channel or a carrier Molecules move down a concentration gradient, from high [ ] to an area of low [ ] – Ex. Large molecules like glucose (sugar = C6H12O6) and polar molecules like calcium (Ca+2) Over time…  Passive Transport: Osmosis The simple diffusion of water across the cell membrane. Water molecules move down a concentration gradient, from high [water] to an area of low [water] until equilibrium is reached. – High water concentration means low solute concentration. – Low water concentration means high solute concentration. Over time…  Passive Transport: Osmosis Hypertonic solutions: water [ ] is lower than the cell’s cytoplasm. – Net movement of water out of cell  Cell shrivels Hypotonic solutions: water [ ] is higher than the cell’s cytoplasm. – Net movement of water into a cell  Cell swells Isotonic solutions: identical water [ ] to cell’s cytoplasm  Cell stays the same  Passive Transport: Osmosis Hypertonic Hypotonic Isotonic H 2O H 2O H 2O H 2O H 2O H 2O Cell stays the Cell shrivels Cell swells same  Pause and Practice ENVIRONMENT CELL 10% NaCl 90% H2O 20% NaCl 80% H2O The cell is in a solution and will  Pause and Practice ENVIRONMENT CELL 10% NaCl 90% H2O 20% NaCl 80% H2O The cell is in a HYPOTONIC solution and will SWELL  Pause and Practice ENVIRONMENT CELL 15% NaCl 85% H2O 5% NaCl 95% H2O The cell is in a solution and will  Pause and Practice ENVIRONMENT CELL 15% NaCl 85% H2O 5% NaCl 95% H2O The cell is in a HYPERTONIC solution and will SHRIVEL  Pause and Practice ENVIRONMENT CELL 10% NaCl 90% H2O 10% NaCl 90% H2O The cell is in a solution and will  Pause and Practice ENVIRONMENT CELL 10% NaCl 90% H2O 10% NaCl 90% H2O The cell is in a ISOTONIC solution and will STAY THE SAME  Active Transport: Molecular Pumps When a cell uses energy to pump molecules across the membrane, against the [ ] gradient, through a protein channel. This allows a cell to concentrate key molecules within the cell, or remove waste quickly from the cell. – Ex. Potassium (K+), chlorine (Cl-) and sodium (Na+) = ions (charged particles) ENERGY Over time…  Active Transport Using Vesicles Endocytosis uses vesicles to move large particles into the cell. – Ex. When white blood cells engulf bacteria in order to fight infection. Exocytosis uses vesicles to export materials out of the cell. – Ex. When nerve cells secrete neurotransmitters to send signals throughout the body. Endocytosis Exocytosis  Active Transport Using Vesicles 2 Types of Endocytosis: – Phagocytosis = cell “eating” Cell engulfs solids into vesicle and “digests” them – Pinocytosis = cell “drinking” Cell engulfs liquids into vesicle and “digests” them  Summary Type of Passive/Active Ex. of substances Ex. of how it helps Transport transported this way maintain homeostasis Facilitated Regulates blood sugar Diffusion Active Neurotransmitters Endocytosis Captures bacteria Controls blood pressure Passive by regulating blood volume Passive O2 and CO2 Muscle contractions and K+, Na+, Ca2+, Cl- nerve signal conduction Practice Types of Cell Transport Lab Exploring Osmosis Practice Putting it all together