1 / 9

Cell Membrane & Transport of materials

Cell Membrane & Transport of materials. Section 6. Cell/Plasma Membrane. Cell membrane surrounds all cells Cell membrane consists of phospholipid & protein molecules This forms the fluid mosaic model. Phospholipid Bilayer. Phospholipids arranged into a double layer (bi-layer)

brita
Download Presentation

Cell Membrane & Transport of materials

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. Cell Membrane & Transport of materials Section 6

  2. Cell/Plasma Membrane • Cell membrane surrounds all cells • Cell membrane consists of phospholipid & protein molecules • This forms the fluid mosaic model

  3. Phospholipid Bilayer • Phospholipids arranged into a double layer (bi-layer) • Hydrophilic heads form hydrogen bonds with water on either side of the cell • Hydrophobic tails face inwards • Cholesterol is also a component of the bilayer • Structure is fluid, yet is a stable boundary • Tiny molecules can pass through easily

  4. Proteins • Proteins are spread throughout the phospholipid bilayer. • FUNCTIONS: • Support • Channels :allowing small molecules through the membrane • Carriers: actively pump molecules across • Enzymes: catalysing reactions at the membrane • Receptors: for hormones to attach to • Markers: Identify cell’s blood/tissue type

  5. Other membranes • Many organelles have membranes • Nucleus – double membrane • Mitochondrion – folded inner membrane • Endoplasmic Reticulum & Golgi – membranes can pinch off = vesicles • All membranes are selective barriers • Entry/exit of materials is regulated

  6. Modes of transport - diffusion • Molecules/ions move along a concentration gradient • Process is passive (no energy) • Small molecules diffuse easily through tiny pores • Larger molecules cannot diffuse • Membrane is selectively permeable

  7. Osmosis • Movement of water from HWC to LWC through a selectively permeable membrane • In red blood cells: • In hypotonic solution – burst • In isotonic solution – no change • In hypertonic solution – shrink (plasmolysed)

  8. Active Transport • Movement of molecules against a concentration gradient • Requires ATP energy • Protein molecules are carriers – recognise specific ions/molecules • Sodium/Potassium pump exchanges ions back and forth • Important in nerve cells • Affected by temperature, oxygen, & glucose availability

  9. Endocytosis/Exocytosis • Endocytosis: a cell engulfing large particles • A ‘pouch’ is formed – forms an intracellular vesicle • 1) Phagocytosis • – engulfing of solid particles • (e.g. against bacteria) • 2) Pinocytosis – engulfing of liquid • Exocytosis: Vesicles from inside, fuse with membrane, and contents expelled • e.g. enzymes, hormones secreted

More Related