Biology - Biological Molecules - Carbohydrates

• Maltose is made up of...

  Glucose + Glucose
• Sucrose is made up of...

  Glucose + Fructose
• Lactose is made up of...

  Glucose + Galactose
• Formula for Carbohydrates:


  Cx(H2O)y
• Why use starch for storage?


  Insoluble - doesn't effect water conc. of the plant cell.

  Large molecule - cannot diffuse out of the plant cell membrane.

  Alpha Glucose - easily transported and readily used.

  Amylopectin is branched - glucose released rapidly because more ends are hydrolysed by enzymes (hydrolysis reaction)
• Why not use glucose for storage? (in plants)

  Small - Can be lost easily

  Soluble - Reduces water conc.
• What two glucose polymers is starch made up of?

  Amylose and Amylopectin
• Amylose:


  Alpha Glucose

  1,4 Glycosidic Bonds

  Spiral Structure

  Breaks down slower than Amylopectin (Only two terminal ends)
• Amylopectin:


  Alpha Glucose

  1,4 and some 1,6 glycosidic bonds

  Branched Structure

  Breaks down faster than Amylose (more terminal ends)

  - The process of breaking down Amylopectin is called a hydrolysis reaction. (broken down by adding water)
• What is the positive food test for starch?


  Iodine turns from brown/yellow to blue/black for a positive result
• Glycogen:

  Storage molecule for animals.

  Insoluble.

  Alpha glucose.

  1,4 and 1,6 glycosidic bonds, giving it a branched structure. Easily hydrolysed.

  Stored in the muscles and liver.
• Cellulose


  Structural polymer - very very strong.

  Beta glucose.

  Straight unbranched chains that are parallel with eachother.

  Hydrogen bonds form cross linkages between the strands.

  H bonds are weak alone, but strong together - these give cellulose its strength.
• Beta Glucose


  See image below

  
• Alpha Glucose


  See image below