Carbohydrates

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Carbohydrates
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Organic Molecules

• Giant molecules are called Macromolecules
• Most macromolecules are Polymers
• Polymer large molecules consisting of many
  identical or similar subunits strung together
• Subunits of a polymer are Monomers

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Dehydration Synthesis

• Monomers are linked together by Dehydration
  Synthesis
• The net effect of this process is the removal of
  a water molecule for each monomer in the chain
• This type of reaction is called a Dehydration
  Synthesis

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Joining Two Monomers

• Two monomers join when one monomer loses an -OH
  and the other loses a H
• Energy is required
• This process occurs only with the help of enzymes

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Disassembling Polymers

• Polymers are disassembled to monomers by
  Hydrolysis
• Bonds between monomers are broken down by the
  addition of water
• H from water attaches to one monomer and the -OH
  attaches to the other
• This is the reverse of Condensation Synthesis
  Ex. Digestion

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4 Major Classes of Organic Compounds

• 1. Carbohydrates
• 2. Lipids
• 3. Proteins
• 4. Nucleic Acids

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Carbohydrates

• Includes all sugars and their polymers
• Simplest form Monosaccharide (simple sugars)
• Double Sugar Disaccharide (made up of 2
  monosaccharides) joined by a dehydration
  synthesis reaction
• Polymers of many sugars Polysaccharide

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Disaccharide
Polysaccharide
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Monosaccharides

• General Formula is CH2O
• The number of these units ranges 3-7 carbons long
• Most common Monosaccharide is GLUCOSE C6H12O6
  which is a major cellular fuel.

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Monosaccharide Functional Groups

• Hydroxyl attached to each Carbon except one
• One carbon is double bonded to oxygen to form a
  carbonyl group
• Depending on the location of the carbonyl, a
  sugar is either
• aldehyde
• ketone
• alcohol

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• Glucose is an ALDOSE (hexose)
• Fructose is a KETOSE (hexose)

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• Another source of diversity in simple sugars is
  the spatial arrangement of their parts around
  symmetric carbon atoms
• In aqueous solutions, glucose and other sugars
  form rings.
• Glucose is broken down to yield energy in
  cellular respiration.
• Monosaccharides are the building blocks for
  synthesis of other smaller organic molecules.

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Disaccharides

• Double sugars that consist of 2 monosaccharides
  joined by dehydration synthesis and a covalent
  bond between monosaccharides
• Examples
• Maltose 2 Glucose (beer, seed germination)
• Lactose Glucose Galactose (milk)
• Sucrose Glucose Fructose (plant sugar)

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Oligosaccahrides

• Short chains made of 2 or more monomers
• When 3 or more monomers are present they are
  sometimes attached as side chains to proteins and
  aid in membrane function

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Polysaccharides

• Made up of a few 100 to a few 1,000
  Monosaccharides
• Can be straight or branched chains

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Storage Polysaccharides

• Used as a storage material. Ex. Starch - consists
  of only glucose and can be hydrolyzed when needed
  to produce sugar
• Simplest form of starch Amylose - unbranched
• Plants store starch to save up sugars carb.
  Banking for long term energy needs

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Animal Energy Needs

• Most animals have enzymes to hydrolyze plant
  starch to make glucose available as a nutrient
  for cells
• Animals produce/store Glycogen, a highly branched
  polymer of glucose, as their energy storage form.
• Humans store glycogen in the muscles liver
  cells.

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Animal Energy Needs

• Humans hydrolyze the glycogen to release glucose
  when sugar demand increases
• The Bank depletes within a day but gets
  replenished by eating more food.

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Structural Polysaccharides

• Used for support
• ex. Cellulose - found in Cell Wall of plant
  cells. Its one of the most abundant organic
  compounds on Earth
• Cellulose is tough insoluble

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Cellulose

• Like starch, cellulose is a polymer of glucose,
  but the configuration of the ring form of glucose
  differs.
• In cellulose, the glucose monomers are in the
  Beta configuration. This means that the hydroxyl
  is locked above the plane of the ring.

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Starch

• In starch the glucose monomers are in the alpha
  configuration. This means that the hydroxyl is
  locked below the plane of the ring.
• This variation in geometry of starch and
  cellulose allows each to have different
  properties.

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Enzymes

• Enzymes that digest starch by hydrolyzing the
  alpha bonds are unable to hydrolyze the beta
  linkages of cellulose.
• Humans dont have the enzymes that can break the
  beta link.
• Cellulose then becomes undigestable dietary fiber
  (roughage)

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Put in your NOTECARDS

• 1. Explanation of Dehydration Synthesis
• 2. Explanation of Hydrolysis
• 3. The General Formula for a Carbohydrate
• 4. Explain the difference between a
  Monosaccharide and a Polysaccharide
• 1 NOTECARD