AICE carbohydrates unit 2 part one

General formula- (CH2O)n

n = number of carbons

ratio- equal numbers of C and O with twice H (ex C6H12O6)

most abundant biological molecule.

most ends in “-ose”

3 main types:

1. Monosaccharides (monomer)

2. Disaccharides (polymer)

3. Polysaccharides (polymer)

Monosaccharides

• white, water-soluble, polar, solids.

• Classified by # of C

  5 C - pentose

  6 C - hexose

• Are straight chains or rings

• Most common: glucose (hexose)

  • Main functions:

    • source of energy for cell respiration (broken O-H bonds release energy)

    • most important sugar in energy metabolism: glucose

    • building blocks for larger molecules

Hexose sugars to know:

• Glucose- “blood sugar” immediate source of energy in cell respiration (OH on left is on bottom)

• Galactose- found in dairy products (OH on left is on top)

• Fructose- found in honey/fruits (pentagon shape)

  
  

Numbering carbons: clockwise

Alpha glucose: hydroxyl on C1 points DOWN

Beta glucose: hydroxyl on C1 points UP

Disaccharides:

• 2 monosaccharides combined via condensation reaction

• 1 mono. loses a H atom and the other loses a hydroxyl group

• forms a glycosidic bond

• 3 common disaccharides

  Sucrose- (glucose + fructose)

  • common table sugar, and food reserve in plants

  Lactose- (glucose + galactose)

  • sugar in mammal milk

  Maltose- (glucose + glucose)

  • 1st product of starch digestion, broken down to glucose later

Polysaccharides:

• long chains of mono. combined by condensation reactions

• NOT water soluble

• good for long-term storage or energy or strong structures

Glycogen:

• energy storage in animals and fungi

• chain of Alpha glucose linked by glycosidic bonds

  • 1-4 links, with 1-6 links that form branches

• HIGHLY BRANCHED

Starches:

• energy storage in plants

• chain of Alpha glucose with glycosidic bonds

• not soluble in water

• mixture of amylose and amylopectin

  • amylose- linear, unbranched, Alpha glucose molecules, with ONLY 1-4 glycosidic bonds

  • amylopectin- branched chains of Alpha glucose with 1-4 AND 1-6 glyco. bonds

Cellulose:

• most abundant organic molecule

• plant cell walls

• Beta glucose with 1-4 glycosidic bonds, NO BRANCHES, long strands, hydrogen bonds hold strands together to form fibers.

• difficult to digest (only cows and termites have the gut to digest cellulose)

• the molecules are rotated 180 degrees next to each other.

  the straight chains that form bundles- microfibrils