Molecules of Life

1
Chapter 5

• Molecules of Life

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Organic vs. Inorganic

• All compounds may be classified into two broad
  categories
• organic compounds - carbon based molecules
• inorganic compounds - almost all are non-carbon
  based molecules

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Carbon (C)

• Carbon has 4 electrons in outer shell.
• Carbon can form covalent bonds with as many as 4
  other atoms (elements).
• Usually with C, H, O or N.
• Example CH4(methane)

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Carbon Bonding

• Carbon can also bond with other carbon atoms
• Forms three types of structures
• Straight chains
• Branched chains
• Rings

5
Carbon bonding

• Carbon can share one, two or three electrons with
  another atom
• single bond - one electron shared
• double bond - two electrons shared
• triple bond - three electrons shared

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Macromolecules

• Large organic molecules.
• Also called POLYMERS.
• Made up of smaller building blocks called
  MONOMERS.

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How Are Macromolecules Formed?
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Answer Dehydration Synthesis

• Also called condensation reaction
• Forms polymers by combining monomers by removing
  water.

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How are Macromolecules separated or digested?
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Answer Hydrolysis

• Separates monomers by adding water

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Macromolecules

• FOUR MAIN CATEGORIES
• 1) carbohydrates fuel building material
• 2) lipids fats oils
• 3) proteins perform most cell functions
• 4) nucleic acids information storage (Chap.
  11)

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Carbohydrates
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Carbohydrates

• Carbohydrates are made of sugar molecules
• Sugars contain carbon, hydrogen, and oxygen in
  the following ratio
• 1 carbon 2 hydrogen 1 oxygen

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3 main types of carbohydrates

• Monosaccharide one sugar unit
• Ex glucose, fructose
• Disaccharide two sugar units
• Ex Sucrose (glucosefructose)
• Polysaccharide many sugar units
• Ex starch found in plants (bread, tomatoes)
• Ex Glycogen found in animal cells

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Carbohydrates

• Most carbohydrates are polar and hydrophilic
• Hydrophilic attracted to water molecules
• Monosaccharides and disaccharides easily dissolve
  in water to form sugar solutions

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Lipids
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Lipids

• Lipids are not soluble in water.
• They are nonpolar and hydrophobic? do not mix
  with water
• Lipids store the most energy
• Examples
• Fats, oils
• Phospholipids
• Steroid hormones
• Triglycerides

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Lipids

• Six functions of lipids
• 1. Long term energy storage
• 2. Protection against heat loss (insulation)
• 3. Protection against physical shock
• 4. Protection against water loss
• 5. Chemical messengers (hormones)
• 6. Major component of membranes (phospholipids)

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Simplest Fats

• Triglycerides
• composed of 1 glycerol and 3 fatty acids.

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Fatty Acids

• There are two kinds of fatty acids
• 1. Saturated fatty acids no double bonds (bad)
  
• solid at room temperature, Ex butter
• 2. Unsaturated fatty acids at least 1 double
  bonds (good)
• liquid at room temperature, Ex Fruits, olive
  oil

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Steroids

• Classified as lipids ? are hydrophobic
• Differ from fats in structure function
• Some act as chemical signals or hormones ?
  estrogen and testosterone

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Proteins
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Functions of Proteins

• Form structureshair, fur, muscles
• Provide long-term nutrient storage
• Circulate and defend the body against
  microorganisms (antibodies)
• Act as chemical signalshormones
• Help control chemical reactions in cellsenzymes

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Protein Structure

• Proteins are polymers formed from monomers called
  amino acids.
• Amino acids bonded together by peptide bonds
  (polypeptides).
• There are 20 different kinds of amino acids.

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Amino Acid Structure

• Three of central carbons partners are the same
  in all of the 20 different amino acids
• 1. hydrogen atom
• 2. carboxyl group
• 3. amino group

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Amino Acid Structure

• Differences between one amino acid and another
  are due to the unique R group or side group
  that each one has
• Each R group is responsible for a different
  chemical property for each amino acid

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Protein Shape

• Functional proteins consist of precisely twisted,
  coiled, and shaped polypeptides
• Proteins cannot function correctly if shape is
  altered
• Denaturation loss of normal protein shape
• Unfavorable changes in temperature, pH, or other
  environmental conditions may cause proteins to
  become denatured

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Enzymes are proteins that speed up specific
reactions in cells
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Activation Energy

• Activation energy minimum energy required to
  start chemical reaction
• Catalysts compounds that speed up chemical
  reactions
• Enzymes proteins that act as catalysts for
  chemical reactions in organisms

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How Enzymes Work

• ACTIVE SITE MODEL
• Substrate specific reactant acted on by an
  enzyme
• Active site specific region of the enzyme that
  the substrate fits into
• Substrate binds to enzymes active site where the
  substrate undergoes a change