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M6

Page history last edited by gerryc 12 years, 3 months ago

M6.Polysaccharides and lipids are important macromolecules in cells and organisms.

 

Student Outcome: M6.1

Know that polysaccharides, including cellulose and chitin, and phospholipids, contribute to the structural components of cells and organisms.

 

Carbohydrates - Polysaccharides

  • Consist of CHO backbone
  • Made up of monomers called monosaccharides (eg glucose)
  • Monomers can join together to form disaccharides (eg sucrose)
  • Polysaccharides are a chain of monomers generally used for storage of energy.
  • Examples include starch (in plants), glycogen (in animals)
  • Polysaccharides are used for structural purposes. For example, cellulose (fibre) is used for construction of the cell wall in plants; and chitin is the hard outer covering found in insects.

 

Cellulose is a long (100's) polymer of Glucose molecules. However the orientation of the sugars is a little different to starch or glycogen. In Cellulose, every other sugar molecule is "upside-down". This small difference in structure makes a big difference in the way we use this molecule.

 

 


Student Outcome: M6.2

Know that polysaccharides, including starch and glycogen, and lipids, including fats and oils, contribute to energy reserves in cells.

 

 

Energy Reserves in Cells

  • polysaccharides are responsible for the storage of energy in cells
  • in animals the specific molecule is glycogen and in plants it is starch
  • glycogen is usually stored in the liver or in muscle cells where energy demands are the greatest.
  • lipids are produced in humans when there is excess polysaccharides and are more a long term storage molecule.

 

Go here for a simulation showing how much energy each type of food has.  Go to the challenge if you think you know it all.

 

Here is some more information on Lipids. Too much detail for us, but it has some good diagrams, especially of phospholipids which are important in the cell membrane.

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