2.3 Carbohydrates and Lipids

Carbohydrates

  • These compounds contain carbon, hydrogen, and oxygen
  • The function of carbohydrates is to be the main source of energy. The energy stored in the bonds of carbohydrates can be released in the process of cellular respiration to create chemical energy (ATP)
  • Carbohydrates are hydrophilic (water loving). They can easily dissolve into cells and be transported into body fluids.
  • There are 3 categories of carbohydrates:

a)monosaccharides

b)disaccharides

c)polysaccharides

a)Monosaccharides

  • The building blocks of carbohydrates
  • “simple sugars”
  • There are 3 main monosaccharides and they are ISOMERS or one another
  • ISOMERS: molecules which have the same molecular formula but different structural formulas

______: ______

  • The most common monosaccharide
  • Source of energy; the carbohydrate that is broken down in cellular respiration

Structural Formula:

α-glucose (“alpha glucose”) β-glucose (“beta glucose”

______: ______

  • Found in yogurt and milk

Structural Formula

______: ______

  • Found in honey

Structural Formula:

  • Other monosaccharide includes ribose and deoxyribose which are found in nucleic acids (our genetic material)
  • Ribose is a 5-carbon sugar (pentose sugar)

RIBOSE:______DEOXYRIBOSE:______

Structural Formula:Structural Formula:

▪ Found in RNA ▪ Found in DNA

b)Disaccharides

  • Contain 2 monosaccharides chemically bonded together
  • The production of a disaccharide is a condensation reaction and anabolic
  • If we were to take a disaccharide and break it down into 2 monosaccharides, it would be a hydrolysis reaction
  • There are 3 main disaccharides:

i)______ ( ______+ ______ ______+ ______)

  • Sugar in beer

ii)______ ( ______+ ______ ______+ ______)

  • The sugar found in mammalian milk

iii)______ ( ______+ ______ ______+ ______)

  • Table sugar; very sweet

c)Polysaccharides

  • 3 or more monosaccharides bonded together (via condensation reactions)
  • Provide energy storage and carbohydrate storage for organisms
  • Ex: glycogen, starch, cellulose
  • These 3 molecules are made by linking together glucose molecules yet their structure and function are very different due to the type of glucose and type of linkages

Glycogen

  • Made of repeating (alpha) glucose units
  • Animals store extra glucose molecules as glycogen in their liver an muscle cells for short term energy storage
  • When more energy is required in between meals, the cells will release glycogen to be converted back into individual glucose molecules that can be used in cellular respiration to obtain energy
  • Similar to starch but with more branching

Starch (Amylose + Amylopectin)

  • Carbohydrate storage molecule found in plants
  • Made of 100’s of (alpha) glucose molecules
  • There are two forms of starch:
  • Amyloseis unbranched and forms a helix. It has α-1,4 glycosidic bonds
  • Amylopectinis branched and has a globular shaped. It has α-1,4 glycosidic bonds and α-1,6 glycosidic bonds

Cellulose

  • Also found in plants
  • Made from unbranched chains of beta glucose molecules, linked together with 1,4-glycosidic bonds
  • Cellulose provides strength and structure to plant cell walls. (Makes them rigid)
  • Cellulose prevents plant cells from bursting even in high pressures under hypotonic conditions.