Chapter 5.2 Summary

Carbohydrates provide fuel and building material

• Sugars:
• Carbohydrate: an organic compound made up of sugar molecules
• Sugar formula: 1 carbon, 2 hydrogen, 1 oxygen
• Core of sugar molecules are carbon skeletons with a ring shape
• Monosaccharides: Simple sugars containing one sugar unit
• Examples: glucose, fructose, galactose:
• Sugar molecules are main fuel supply for cellular work
• Cells break down glucose to extract energy
• Dissacharides: Two monosaccharides linked together
• Most common dissacharide is sucrose
• Polysaccharides:
• Polysaccharides: Long polymer chains made up of simple sugar monomers
• Starch: A polysaccharide found in plant cells
• Starch chains are sugar stockpiles
• Starch is broken down for glucose
• Glycogen: The polysaccharide animal cells use to store excess sugar
• Glycogen is usually stores as granules in liver and muscle cells
• Cellulose: A polysaccharide in plants used as a building material
• It protects and stiffens plants
• Humans cannot digest cellulose/fiber
• Most carbs are hydrophilic because of hydroxyl groups in sugar unites
• Monosaccharides and dissacharides dossolve easily in water
• Larger carbs (starch, cellulose) can't be dissolved but are still hydrophilic
  

starch:

Concept Check 5.2

1) Explain the difference between a monosaccharide and a dissacharide. Give an example.

Monosaccharides, such as glucose, consist of only one sugar unit while dissacharides, such as sucrose, consist of two sugar units bonded together

2) Compare and contrast starch, glycogen, and cellulose.

Starch, glycogen, and cellulose are all polysaccharides. Starch and glycogen are used to store energy in cells. Starch however is only found in plant cells, while glycogen is found in animal cells. Cellulose is a polysaccharide found in plants that protects the cells and stiffens the plant to prevent it from flopping over.

3) How do animals store excess glucose molecules?

Animals store glucose in the form of a polysaccharide called glycogen. glycogen is usually stored as granules in the liver and muscle cells. When the energy is needed, the glycogen granules are broken down to release the glucose.