What is the chemical basis of life?

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What is the chemical basis of life?

• What are some of the ideas central to the
  chemistry of life?
• (Key concepts of the chemical basis of life)

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Ideas central to the chem of life

• Based on covalent bonding
• Carbon is the backbone of biomolecules
• Simple building code
• Variation on common theme in extreme
• Only 4 fundamental types of biomolecules
• Enzymes make and break the covalent bonds in the
  chemical reactions in the cell
• Isomers and polymers
• Condensation and Hydrolysis

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Elements Essential to Life

• About 25 of the 92 natural occurring elements are
  essential to life
• CHON 96 liv mat
• CHONPS gt 99

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Famous ions in Biology

• Hydronium H3O and Hydroxide OH-
• Potassium K ions
• Sodium Na ions
• Calcium Ca2 ions
• Hydrogen H ions (protons)

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A continuum view of bonding

• Atoms complete their valence shell in a continuum
  of
• Nonpolar covalent with equal sharing of e-
• Examples HH O O
• Polar covalent, unequal sharing of e-
• Examples H2O NH3
• Ionic, with complete transfer of e-
• Examples NaCl Al2O3

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Weak Bonds are Bioly ImportantH bonds,
hydrophobic interactions

• Can form between different parts of a single
  large molecule or between molecules
• Help stabilize 3D shape of proteins Nucleic
  Acids
• Hold enzymes to substrates
• Function in chemical signaling

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Biological Building Codes

• Covalent Bond shared pair of electrons between 2
  nonmetals
• H, 1 unpaired e-
• O, 2 unpaired e-
• N, 3 unpaired e-
• C, 4 unpaired e-

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Versatility of Carbon

• 4 valence electrons
• Compatibility with many different els
• S, D, T bonds
• Makes large, complex molecules possible
• Strait chains
• Branched chains
• Rings

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• Polymer
• (poly many mer part)
• Large molecules consisting of many similar
  subunits connected together
• Monomer subunit or building block of polymer

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Macromolecules are Polymers

• Carbohydrates polymer of monosaccharides
• Lipids polymer of fatty acids glycerol
• Proteins polymer of amino acids
• Nucleic Acids polymer of nucleotides

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Polymers Molecular Diversity

• Unity in life Only about 40 or 50 common
  monomers build macromolecules
• Diversity in life New properties emerge when
  these monomers are arranged in different ways

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Sucrose Synthesis
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Hydrolysis
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Making Breaking Polymersanimation

• Dehydration synthesis
• Link monomers
• Via removal of H2O
• 1 water per link (out)
• One monomer lose OH, other loses H
• Any assembling of molecules in cells

• Hydrolysis
• Disassemble polymers
• Via addition of H2O
• 1 water per link (in)
• One monomer gains OH, other gains H
• Any disassembly of molecules in cells

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Carbohydrates (sugars)

• Classified based on of simple sugars
• C H O in 121 ratio
• Major nutrients for cells ie glucose
• Produced by photosynthetic organisms
• Store energy in chemical bonds
• C skeletons raw materials for other organic
  compounds

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Carbohydrates-disaccharides

• Disacch. Monomers
• Maltose glu glu
• Lactose glu galac
• Sucrose glu fru

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Carbohydrates Polysaccharides

• 2 Important biological functions
• Energy storage (starch, glycogen)
• Structural support (cellulose, chitin)

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Storage Polysaccharides

• Starch glucose polymer, for energy storage in
  plants
• Helical glucose polymer
• Most animals have enzymes to hydrolyze it
• Major sources in
• Human diet are potatoes
• And grains

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Storage Polysaccharides

• Glycogen glucose polymer, for energy storage in
  animals
• Branched molec.
• Stored in muscle
• and liver of humans
• and other vertebrates

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Structural Polysaccharides

• Cellulose linear unbranched polymer
• Major structural component of plant cell walls
• Differs from starch in its monomer linkage
• Cannot be digested by most organisms

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Structural Polysaccharides

• Chitin structural polysacch. a polymer of an
  amino sugar (natures plastic)
• Forms exoskeleton of Arthropods
• Found as cell walls in fungi

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Lipids

• Diverse group of organic compounds that are
• insoluble in water
• Includes animal fats,
• plant oils, steroids,
• phospholipids
• Made of fatty acids
• and glycerol

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Fat

• Saturated
• All single bonds
• Solid at room temp
• Animal fats

• Unsaturated
• One or more double bonds between carbons
• Liquid at room temp
• Vegetable or plant oils

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Useful functions of fat

• Energy storage
• More compact fuel reserve than carbo.
• Cushions vital organs in mammals
• Insulates against heat loss

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Phospholipids

• Component of cell membranes (bilayer)
• 2 fatty acids phosphate group
• Amphipathic behavior in water

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Steroids

• Lipids w/ 4 fused carbon rings and various
  functional groups
• Cholesterol important as precurser to other
  steroids and enhance membrane fluidity

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Proteins

• Complex polymers of amino acids
• Abundant make up 50 or more of dry wt
• Varied functions in cell structure, metabolism,
  transport, signaling, movement, defense
• Each has unique 3-D shape
• Made of only 20 different amino acids

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Amino Acid Structure
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Nucleic Acids

• Deoxyribonucleic Acid (DNA)
• Can replicate itself and be passed from one
  generation of cells to the next
• Genes are segments of DNA that code for protein

• Ribonucleic Acid (RNA)
• Functions as mediator between genotype and
  phenotype
• 3 functional forms carry out protein synthesis

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Nucleic Acids

• DNA, the Genetic Code

• RNA the Trait Maker

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Nucleotides monomers of nucleic acids

• Pentose, a 5C sugar
• Nitrogen Base
• Phosphate