Section 33 Molecules of Life

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Section 3-3 Molecules of Life
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Organic Compounds

• Carbohydrates
• Proteins
• Lipids
• Nucleic Acids

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Carbohydrates

• Composed of carbon, hydrogen, oxygen
• Ratio of two hydrogen to one oxygen
• Functions
• Fuel
• Building Materials
• Examples monosaccharides, polysaccharides

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Monosaccharides

• Simple sugars
• Contain carbon, hydrogen, and oxygen in a 121
  ratio
• Examples glucose, fructose, galactose (isomers
  same formula/different forms)
• Function - Fuels

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Disaccharides

• Double sugars

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Polysaccharides

• Composed of three or more monosaccharides
• Starch food storage in plants
• Glycogen food storage in animals

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Polysaccharides continued

• Cellulose support in plant cell walls
• Chitin support in cell walls of fungi and
  exoskeletons of arthropods

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Proteins

• Composed primarily of carbon, hydrogen, oxygen,
  and nitrogen
• Monomers are amino acids
• Functions
• structural support
• regulation of metabolism - enzymes

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• Amino Acids
• 20 types
• Composed of four parts
• 1. Single hydrogen (H)
• 2. Amino group (-NH2)
• 3. Carboxyl group (-COOH)
• 4. Functional (R) group (varies)

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Polypeptides

• Polypeptide a chain of amino acids (protein)
• Amino acids are joined by peptide bonds formed by
  condensation reactions.

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• Enzymes catalysts in living things
• Work based on shape
• Substrate fits into specific site on the enzyme
• Shape may change if environment (pH, temperature)
  changes (enzyme stops working)
• When homeostasis returns, the shape returns to
  normal and (enzyme begins working again)
• (Based on this, describe what happens when you
  have a fever.)

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Lipids

• Composed of hydrogen, carbon, and oxygen
• No specific ratio, but much more carbon than
  oxygen
• Nonpolar do not dissolve in water
• Functions
• Efficient energy storage
• Hormones

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• Fatty Acids
• Long, straight chain of hydrogen and carbon with
  a carboxyl (-COOH) end
• Carboxyl end is polar and hydrophilic (water
  loving).
• Hydrocarbon end is nonpolar and hydrophobic
  (water fearing)

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• If there are no double bonds, then the
  molecule is a saturated fatty acid.

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• If there are one or more double bonds, then the
  molecule is an unsaturated fatty acid.

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Complex Lipids

• 1. Triacylglycerol (fat) three fatty acids and
  a glycerol

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• 2. Phospholipids two fatty acids, glycerol,
  phosphate
• Phosphate head is hydrophilic.
• Fatty acid tails are hydrophobic.
• Cell membranes are made of a phospholipid bilayer

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• 3. Steroids (cholesterol and certain hormones)
  four fused carbon rings

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Nucleic Acids

• Composed of nucleotides (sugar, phosphate,
  nitrogen base)
• Functions
• Store information
• Carry information
• Two Types
• DNA (deoxyribonucleic acid)
• RNA (ribonucleic acid)

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