Chapter 3- The Chemistry of Organic Molecules Section 2- Carbohydrates

carbohydrates- Class of organic compounds that typically contain carbon, hydrogen, and oxygen in a 1:2:1 ratio; includes the monosaccharides, disaccharides, and polysaccharides.

The primary function of carbohydrates in living organisms - are used as an immediate energy source

Monosaccharides

• Monosaccharides- Simple sugar; a carbohydrate that cannot be broken down by hydrolysis (e.g., glucose); also, any monomer of the polysaccharides.

• Pentoses- Five-carbon monosaccharide. Examples are deoxyribose found in DNA and ribose found in RNA.

• Hexoses- Any monosaccharide that contains six carbons; examples are glucose and galactose.

• Glucose- Six-carbon monosaccharide; used as an energy source during cellular respiration and as a monomer of the structural polysaccharides.

• Ribose- Pentose sugar found in RNA.

• Deoxyribose- Pentose sugar found in DNA.

Disaccharides

• Disaccharides- Sugar that contains two monosaccharide units (e.g., maltose).

Polysaccharides: Energy-Storage Molecules

• Polysaccharides- Polymer made from carbohydrate monomers; the polysaccharides starch and glycogen are polymers of glucose monomers.

  • A polysaccharide is a polymer made up of simple sugars

• Startch- Storage polysaccharide found in plants that is composed of glucose molecules joined in a linear fashion with few side chains.

• Glycogen- Storage polysaccharide found in animals; composed of glucose molecules joined in a linear fashion but having numerous branches.

  • Glycogen is a carbohydrate used to store energy in the liver

Polysaccharides: structural molecules

• Cellulose- Polysaccharide that is the major complex carbohydrate in plant cell walls.

• Chitin- Strong but flexible nitrogenous polysaccharide found in the exoskeleton of arthropods and in the cell walls of fungi.

  • Cellulose and chitin are structural carbohydrate molecules

• Peptidoglycan- Polysaccharide that contains short chains of amino acids; found in bacterial cell walls.

  • Which carbohydrate is found in the exoskeleton of insects and crabs- chitin

    • Which of the following carbohydrates would NOT be molecule used for energy storage?- cellulose

    • A triglyceride is a polymer made up of what kind of subunits?- fatty acids and glycerol

    • A dehydration reaction can also be called a (n) _________ reaction since it forms water.- condensation

    • Organic molecules are those that contain at least- carbon and hydrogen

    • Which carbohydrate is found in the cell walls of plants?- cellulose