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Standard II- Cell Processes

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Standard V-1, Part 2- Cell Processes

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1 Standard II- Cell Processes
Biology AHSGE Standard II- Cell Processes

2 Biology AHSGE Standard 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.

3 Biology AHSGE D. 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.)

4 Homeostasis The 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 nutrients Digestion- Break down of materials into usable substances Absorption- Ability of an organism/cell to take in materials from the outside environment Transport- Movement of substances within an organism/cell Biosynthesis- Making new compounds for growth, repair, or reproduction

5 Homeostasis Homeostasis processes cont’d:
Secretion- Release of substances within an organism/cell Respiration- Release of energy from the breakdown of chemical compounds in the mitochondria Photosynthesis- Autotrophic production of glucose from CO2 and H2O Excretion- Rid of waste products to the outside of the organism/cell Response- Reaction due to a stimulus Reproduction (Fission)- Production of new cells by one cell dividing (mitosis and meiosis)

6 Passive Transport Passive 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 concentration Requires no energy Will continue until all concentrations are the same Dynamic equilibrium- Particles will continue to move without an overall change in concentration.

7 Diffusion

8 Diffusion 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 faster More collisions occur causing diffusion to occur faster

9 Facilitated Diffusion
Facilitated diffusion- Uses transport proteins to move other ions and small molecules across the plasma membrane Passive transport because it does not require energy Water can diffuse across the membrane, but most other substances can not Can use water-filled transport (channel) proteins or Carrier proteins (change shape as material passes through)

10 Osmosis Osmosis- Diffusion of water across a selectively permeable membrane In a solution, a solute is dissolved into a solvent. Water is the solvent in a cell and its environment

11 Osmosis Hypotonic Solution- Solution has a lower concentration of solute and higher concentration of solvent. Cell will be cell will be hypertonic Net movement of water will be into the cell, causing the cell to swell In pure solvents, cells will burst Ex: Distilled water, pure vinegar Hypertonic solution- Solution has a higher concentration of solute and a lower concentration of solvent. Cell will be hypotonic Net movement of water will be out of the cell, causing the cell to shrink

12 Osmosis Isotonic Solution- The solution has the same concentrations of solutes and solvents as the cell. Cell is also isotonic Water will enter and leave the cell at equal rates, allowing for the cell to remain unchanged.

13 Osmosis Practice

14 Active Transport Active transport- Movement of substances across the membrane from an area of lower concentration to an area of higher concentration; against the concentration gradient. Requires energy Uses carrier proteins called pumps Maintains the proper balance of substances it needs to maintain homeostasis

15 Active Transport Sodium-potassium ATPase Pump
Found in cell membrane of animal cells Uses 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

16 Active Transport Endocytosis- Cell surrounds a substance in the outside environment, enclosing it in a portion of the membrane. Pinches off into a vacuole Pinocytosis- Cell drinking Phagocytosis- Cell eating Exocytosis- Vesicles surround waste inside the cell, attach to the cell membrane, and expel materials to the outside environment.

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