Membranes and transport.

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  • Created by: Pudgee
  • Created on: 24-10-17 14:17

Membranes:

  • are partially permeable so regulate the transport of molecules in and out of the cell.
  •  separates cell components from the external environment.
  • may contain enzymes involved in specific metabolic pathways.
  • has antigens so the immune system will recognise the cell as self and not attack. 
  • may release chemicals to signal other cells
  • contains receptors for such signals, and so is a site for cell communication or signalling; hormones and drugs may bind to receptors.
  • may be the site of chemical reactions.
  • form cristae in mitochondria that give a large surface area for aerobic respiration
  • inner membranes of chloroplasts called thylakoid membranes house chlorophyll. 
  • the membranes of epithelial cells that line the small intestine contain some enzymes that catalyse some of the final stages in the breakdown of certain types of sugars

FLUID MOSAIC MODEL

  • phospholipid molecules
  • channel protein
  • carrier protein
  • cholesterol
  • glycoproteins and glycolipids that form the glycocalyx used for signalling and attracting solutes.

DIFFUSION ACROSS MEMBRANES

Simple diffusion

  • all molecules have kinetic energy and can move freely and randomly. 
  • if there is a high concentration of a molecule they will bump into each other and…

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