Lesson 5- Carbohydrates

Question 1

What are carbohydrates composed of?

Answer 1

• Composed of mostly carbon, hydrogen, and oxygen
• Simple molecules but perform complex functions

Question 2

What are Monosacchardies?

Answer 2

• The simplest type or carbohydrate (contains single sugar)
• Typical ratio: 1 carbon, 2 hydrogen, 1 oxygen
• Carbohydrates —> monosaccharides or as long as two or more monosaccharide units linked together
• Glucose: Most widely used monosaccharide.

Question 3

Common Monosaccharides

Answer 3

• Glyceraldehyde
• Ribose
• Fructose
  3 carbons—> triose
  5 carbons—> pentose
  6 carbons—> hexose
• 5 or more carbons will fold to form a ring
  Due to reaction between two functional groups in the same monosaccharide.

Question 4

Glucose

Answer 4

• Can form 2 possible rings (a-glucose or b-glucose)
• These are isomers (same chemical formula but different arrangement of the atoms)
• The different arrangements of the -OH can give different properties
• Humans can digest a-glucose but b-glucose is completely indigestible.
• Carbonyl group reacts with a hydroxyl group.

Question 5

Glucose, Fructose, Galactose

Answer 5

• Glucose, fructose, and galactose are isomers of each other.
• Sugars typically have many polar functional groups attached to them -> very hydrophilic. Small sugars are highly soluble in water.
• Monosaccharides are the sweetest carbohydrate —> as the number of monosaccharide units that are linked together increases, the sweetness decreases.

Question 6

Disaccharides

Answer 6

• Consist of two monosaccharides that are joined together by a dehydration synthesis reaction.
  Glycosidic bonds: a bond between two monosaccharides.

Question 7

a and b linkages

Answer 7

• Depends on the orientation of the -OH group bonded to the 1-carbon.
• Linkage in maltose and sucrose is an a-linkage
• Linkage in lactose is a b-linkage.

Question 8

Shorthand Representation

Answer 8

Glycosidic bonds:
- 1-carbon and 4-carbon is 1,4
- 1- carbon and a 2-carbon is 1.2
- 1-carbon and a 3-carbon is 1,3
1- carbon and 6 carbon is 1,6

Question 9

Polysaccharides

Answer 9

Complex Carbohydrates: A molecule that is composed of hundreds to thousands of monosaccharides limited together
—> essential part of nutrition and a valuable energy source
Polysaccharide molecule: A molecule that contains more than two linked monosaccharides.
—> Glycosidic linkages
Examples: Amylose, Glycogen

Question 10

Cellulose

Answer 10

Main component in plant cell walls.
- the most abundant organic molecule on earth
- Molecules are long and straight and have a very large amount of OH groups —> easy to assemble side by side and forms hundreds or thousands of H bonds
- H bonds give cellulose great strength

Question 11

Chitin

Answer 11

Hard component in insect and crustacean
- Also found in fungal cell walls
One of few carbohydrates that contain functional groups with nitrogen atoms

Question 12

Polymerization

Answer 12

Monomer: A small molecule that can bind chemically to other molecules
Polymer: A large molecule that is formed when monomers link together chemically in a chain
Polymerization: A process in which small subunits are linked to form a large molecule