L3 plasma membrane

• eukaryotic cell contents:

  genetic material in chromosomes (enclosed in nuclear envelope), plasma membrane, complex cytoskeleton
• differences between animal and plant cells:

  • chloroplasts
  • central vacuole and tonoplast
  • cell wall
  • plasmodesmata
• endosymbiosis theory for mitochondria
• function of plasma membrane

  to separate cell from its external environment
• transmembrane proteins can be inside and outside the 


  plasma membrane
• glycocalyx (glycoprotein and glycolipids)-> different for everyone, to determine self from non-self
• kinks in the membrane are due to

  unsaturated hydrocarbon chains-> makes membrane more fluid
• more cholesterol makes the membrane _ fluid

  less
• transmembrane proteins are amphipathic
• membrane proteins functions

  • transport
  • receptors
  • structural
  • cell junctions
  • attachment to cytoskeleton and extracellular matrix
• defective chloride ion channel causes

  cystic fibrosis
• carbohydrates in the plasma membrane are nearly all on the outer surface
• blood types are determined by _ on the surface of red blood cells


  carbohydrates
• endocytosis is when


  material is taken into the cell
• exocytosis is when 


  material is removed from the cell
• phagocytosis

  • uptake of insoluble material
  • pseudopodium grab the material
  • lysosomes bind to vesicle and release digestive enzymes
• pinocytosis (cell drinking)

  • cell pinch membrane into vesicle to take up extracellular fluid
  • non-specific
• receptor-mediated endocytosis

  • binding of macromolecules to specific cell surface receptor triggers endocytosis
  • coated pit to cover in protein (clathrin) to form a cage like structure
  • clathrin is on the outside of the vesicle
• exocytosis process:

  • fusion of vesicle with plasma membrane
  • vesicle contents expelled into surroundings
• why is exocytosis important?

  secretion of proteins (e.g. hormones)