Chapter 2 The Chemistry of Life

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Chapter 2The Chemistry of Life
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2-1 The Nature of Matter

• Living things are made of chemical compounds
• Atom the basic unit of matter
• - made of protons (positive), electrons
  (negative), and neutrons (neutral)
• - Atomic number of protons
• - Atomic mass protons plus neutrons

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• Element a pure substance that consists of just
  one kind of atom
• - Isotopes atoms of the same element with
  different of neutrons
• - example carbon 12, 13, 14
• - Isotopes have the same of electrons so they
  have the same chemical properties

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• - Radioactive Isotopes Have unstable nuclei
  and break down at a constant rate over time used
  to determine age of rocks and fossils, treat
  cancer, and kill bacteria

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• Compound two or more elements bonded in
  definite proportions.
• - example H2O, NaCl
• Chemical Bonds involves valance electrons

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• - Ionic bond one or more electrons are
  transferred from one atom to another, then
  opposite charges attract two ions

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• - Covalent bond electrons are shared between
  atoms
• - Molecule when atoms are joined together by
  covalent bonds

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• - Van der Waals Forces slight attraction
  between oppositely charged regions of nearby
  molecules

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2-2 Properties of Water

• Water is the single most abundant compound in
  most living things.
• Properties
• - Water expands as it freezes ice floats on
  liquid water

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• - Polarity oxygen atom attracts shared
  electrons stronger than the hydrogen atoms
• - causes hydrogen bonds attraction between
  slightly and
• - cohesion attraction between molecules of
  same substance allows beading of water and
  surface tension
• - adhesion attraction between molecules of
  different substances meniscus and capillary
  action
• Water properties website

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• Solutions and suspensions
• - mixture two or more elements physically
  mixed
• - solution mixture with evenly distributed
  molecules
• - solute dissolved substance
• - solvent substance in which solute is
  dissolved
• - suspension mixtures of water and
  nondissolved material

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• Acids, Bases and pH
• - Water can split to form ions
• H2O ? H OH- the ions are
• equal so water is neutral

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• - pH scale indicates the concentration of
  hydrogen ions (H)
• - acids form H ions in water pH value lower
  than 7
• - bases form OH- ions in water pH value
  higher than 7
• - buffers weak acids or bases that can react
  with strong acids or bases to prevent changes in
  pH

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2-3 Carbon Compounds

• Carbon has four valence electrons and forms
  strong chains or rings
• Macromolecules means giant molecules
• - formed by a process of polymerization
• - monomers small units which are joined to
  form polymers

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• - Carbohydrates main source of energy and used
  for structure
• - made of carbon, hydrogen and oxygen, ratio
  121
• - monomers sugars or monosaccharides
  glucose
• - polymers starches or polysaccharides
  glycogen, cellulose

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Starch
Glucose
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• - Lipids energy storage, insulation, makes up
  membranes
• - made of carbon, hydrogen and oxygen
• - examples fats, oils, and waxes
• - saturated no double bonds butter
• - unsaturated has double or triple bonds
  olive oil
• - steroids chemical messengers

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• - Nucleic acids store and transmit hereditary
  information
• - made of hydrogen, oxygen, carbon, and
  phosphorus
• - monomers nucleotides

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• - Proteins control rate of chemical reactions,
  regulate cell processes, form bone and muscle,
  transport substances, fight diseases
• - made of nitrogen, carbon, hydrogen, and
  oxygen
• - monomers amino acids 20 different a.a. in
  nature

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Amino Acid Structure
Amino group
Carboxyl group
General structure
Alanine
Serine
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Proteins form certain structures
Amino acids
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2-4 Chemical Reactions and Enzymes

• Chemical reaction process that changes, or
  transforms, one set of chemicals into another.
• - Equation reactants ? products

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• - Endothermic reaction requires energy
• - Exothermic reaction releases energy can
  occur spontaneously
• - Activation energy needed for most reactions
  to occur

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• Enzymes proteins that act as biological
  catalysts, which speed up chemical reactions in
  the body lowers activation energy
• - usually specific to reaction and not used up
  in reaction

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• - Enzyme-substrate complex site where
  reactants are brought together to react fit like
  a lock and key
• - Enzymes work in specific range of conditions
  pH, temp