1 / 11

CH 3 Section 4 PASSIVE TRANSPORT

CH 3 Section 4 PASSIVE TRANSPORT. One way cells maintain homeostasis is by controlling the movement of substances across their cell membrane. Cells want to reach equilibrium . Equilibrium – is a condition in which the concentration of a substance is equal throughout a space.

wylie-keith
Download Presentation

CH 3 Section 4 PASSIVE TRANSPORT

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. CH 3 Section 4PASSIVE TRANSPORT One way cells maintain homeostasisis by controlling the movement of substances across their cell membrane. Cells want to reach equilibrium. Equilibrium – is a condition in which the concentration of a substance is equal throughout a space

  2. Equilibrium:

  3. Passive Transport – the movement of substances across a cell membrane that does not requireenergy from the cell **passive transport does not require energy because substance are moving along or down the concentration gradient concentration gradient – the difference in the concentration of a substance across a space

  4. 1. Diffusion – the movement of a substance from an area of high concentration to an area of lower concentration

  5. 2. Osmosis – the diffusion of water through a selectively permeable membrane

  6. Three possibilities for the direction of water movement: • hypertonic – the fluid outside the cell has a higher concentration of dissolved particles (or less water molecules) than the inside of the cell therefore, water molecules leave the cell (diffuse out) and the cell shrinks • hypotonic – the fluid outside the cell has a lower concentration of dissolved particles (or more water molecules) than the inside of the cell therefore, water diffuses into the cell and the cell swells • isotonic – the inside of the cell and the fluid outside have the same concentration of free water molecules

  7. Types of Solutions Decreased Dissolved Particles Decrease Dissolved Particles Increased Dissolved Particles Dissolved Particles Equal Increased Dissolved Particles Dissolved Particles Equal

  8. Only molecules that are either very small, can dissolve in fluid, or are nonpolar can diffuse across the cell membrane. The nonpolar interior of the lipid bilayer repels ions and most polar molecules that are not dissolved in fluid. Therefore, the cell membrane is said to be selectively permeable(or semipermeable). Ions, polar molecules, and larger molecules enter the cell through special proteins.

  9. 3. Transport Proteins allow molecules that can’t pass the membrane by simple diffusion to pass. ex: ion channels – are a transport protein which allow ions to pass

  10. Some transport proteins are referred to as carrier proteins because they bind to specific substances on one side of the cell membrane then carry the substance across releasing it on the other side. This is called facilitated diffusion.

More Related