2Biology AHSGEStandard 2. Describe cell processes necessary for achieving homeostasis, including active and passive transport, osmosis, diffusion, exocytosis, and endocytosis.A. Recognize and apply the definition of homeostasis.B. Recognize and apply the definition of active transport. (The movement of a substance across a biological membrane against its concentration or electrochemical gradient with the help of energy input and specific transport proteins.)C. Recognize and apply the definition of passive transport.
3Biology AHSGED. Recognize and apply the definition of osmosis. (The movement of water across a selectively permeable membrane.)E. Recognize and apply the definition of diffusion. (The spontaneous tendency of a substance to move down its concentration gradient from a more concentrated to a less concentrated area.)F. Recognize and apply the definition of exocytosis. (The cellular secretion of macromolecules by the fusion of vesicles with the cell membrane.)G. Recognize and apply the definition of endocytosis. (The cellular uptake of macromolecules and particulate substances by localized regions of the cell membrane that surround the substance and pinch off to form an intracellular vesicle.)
4HomeostasisThe ability of an organism or cell to maintain internal balance and stability by adjusting its physiological processes.If normal state is not restored, death might occur.Processes involved in homeostasis:Nutrition- Use of nutrientsDigestion- Break down of materials into usable substancesAbsorption- Ability of an organism/cell to take in materials from the outside environmentTransport- Movement of substances within an organism/cellBiosynthesis- Making new compounds for growth, repair, or reproduction
5Homeostasis Homeostasis processes cont’d: Secretion- Release of substances within an organism/cellRespiration- Release of energy from the breakdown of chemical compounds in the mitochondriaPhotosynthesis- Autotrophic production of glucose from CO2 and H2OExcretion- Rid of waste products to the outside of the organism/cellResponse- Reaction due to a stimulusReproduction (Fission)- Production of new cells by one cell dividing (mitosis and meiosis)
6Passive TransportPassive Transport- The diffusion of a substance across a biological membrane.Diffusion- The net movement of particles from an area where there are many particles of the substance to an area where there are fewer particles of the substance.High concentration to lower concentrationRequires no energyWill continue until all concentrations are the sameDynamic equilibrium- Particles will continue to move without an overall change in concentration.
8Diffusion 3 factors affect rate of diffusion: Concentration (amount of a substance)Temperature (average kinetic energy of the particles)Pressure (Force of particles against the area of membrane)In each case, the higher, the fasterMore collisions occur causing diffusion to occur faster
9Facilitated Diffusion Facilitated diffusion- Uses transport proteins to move other ions and small molecules across the plasma membranePassive transport because it does not require energyWater can diffuse across the membrane, but most other substances can notCan use water-filled transport (channel) proteins orCarrier proteins (change shape as material passes through)
10OsmosisOsmosis- Diffusion of water across a selectively permeable membraneIn a solution, a solute is dissolved into a solvent.Water is the solvent in a cell and its environment
11OsmosisHypotonic Solution- Solution has a lower concentration of solute and higher concentration of solvent.Cell will be cell will be hypertonicNet movement of water will be into the cell, causing the cell to swellIn pure solvents, cells will burstEx: Distilled water, pure vinegarHypertonic solution- Solution has a higher concentration of solute and a lower concentration of solvent.Cell will be hypotonicNet movement of water will be out of the cell, causing the cell to shrink
12OsmosisIsotonic Solution- The solution has the same concentrations of solutes and solvents as the cell.Cell is also isotonicWater will enter and leave the cell at equal rates, allowing for the cell to remain unchanged.
14Active TransportActive transport- Movement of substances across the membrane from an area of lower concentration to an area of higher concentration; against the concentration gradient.Requires energyUses carrier proteins called pumpsMaintains the proper balance of substances it needs to maintain homeostasis
15Active Transport Sodium-potassium ATPase Pump Found in cell membrane of animal cellsUses energy to transport 3 sodium ions out, while moving two potassium ions in (decreases sodium concentration inside the cell)Coupled transport- Sugar molecules attach to sodium ions to be transported into the cell without energy through the coupled channel
16Active TransportEndocytosis- Cell surrounds a substance in the outside environment, enclosing it in a portion of the membrane.Pinches off into a vacuolePinocytosis- Cell drinkingPhagocytosis- Cell eatingExocytosis- Vesicles surround waste inside the cell, attach to the cell membrane, and expel materials to the outside environment.