Carbohydrates

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Chapter 14

• Carbohydrates

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Chapter 14

• 14.1 - Carbohydrates

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Chemistry of Life
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Carbohydrates

• are produced by photosynthesis in plants
• such as glucose are synthesized in plants from
  CO2, H2O, and energy from the sun
• are oxidized in living cells to produce CO2, H2O,
  and energy

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Types of Carbohydrates

• monosaccharides, the simplest carbohydrates
• disaccharides, consist of two monosaccharides
• polysaccharides, contain many monosaccharides

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Monosaccharides consist of

• 3-6 carbon atoms typically
• a carbonyl group
• aldehyde (aldose)
• ketone (ketose)
• several hydroxyl groups
• carbohydrates that cannot be
• split (or broken down) in to
• smaller carbohydrates

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Monosaccharides (based on of C)
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Chapter 14

• 14.2 Structure of Monosaccharides

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Fischer Projections
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Identifying D and L Isomers

• Look for the chiral carbon furthest from the
  carbonyl group
• Which direction is the hydroxyl group pointing in
  when the carbonyl group is drawn at the top?
• If its on left
• give a L designation
• If its on right
• give a D designation

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Important Monosaccharides

• Most common hexose is D-glucose
• (also known as dextrose or blood sugar)
• Found in fruits, vegis, corn syrup honey
• Building block of disaccharides
• sucrose, lactose and maltose
• Building block of disaccharides
• starch, cellulose and glycogen

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Important Monosaccharides

• Galactose is an aldohexose that does not occur in
  the free form in nature
• Obtained as a hydrolysis product of
• the disaccharide lactose
• Important in the cellular membranes
• of the brain and nervous system
• Only difference from D-glucose is
• the OH arrangement on C 4

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Important Monosaccharides

• Fructose is the sweetest carbohydrate (2x as
  sweet as sucrose table sugar)
• After it enters the bloodstream it is
• converted to glucose
• Found in fruit juices and honey
• Also called levulose and fruit sugar
• Also obtained as one of the
• hydrolysis products of sucrose

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Important Monosaccharides