The Chemistry of Life

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The Chemistry of Life

• Biology, Chapter 2

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Elements

• Building blocks of matter
• Pure substances that contain only one type of
  atom
• examples
• Hydrogen (H), Carbon (C), and Sodium (Na)
• 93 of the human body is made up of 3 elements
  Oxygen, Hydrogen, and Carbon

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The Nature of Matter

• Atoms -- The basic unit of matter
• Made up of subatomic particles
• Protons
• Neutrons
• Electrons

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• Isotope ? atoms of the same element with
  different numbers of neutrons
• Radioactive isotopes ? break down in predictable
  ways
• Can be used to date fossils
• Can be used for medical purposes

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Compounds

• Compound ? a substance formed by the chemical
  combination of two or more elements in definite
  proportions.
• Examples
• One example would be NaCl (sodium chloride or
  table salt).
• Water, H2O is another example
• There are 2 types of compounds
• 1) covalent
• 2) ionic

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Chemical Bonds

• Atoms can bond in two ways
• Covalent bonds form when electrons are shared
  between atoms
• These bonded atoms are called molecules
• Ex H20 (water), CO2
• Covalently bonded atoms are called molecules

Covalent Bond Movie
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• Ionic bonds form when one or more electrons are
  transferred from one atom to another
• Ex NaCl (table salt), FeO, (Iron oxide)
• Ionic Bond Movie

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Characteristics of Water

• Water is Polar.
• Polar means that? there is an uneven
  distribution of charge
• Electrons are shared unevenly
• Hydrogen bonds? when polar molecules attract each
  other.
• Weak bonds that give molecules special
  properties.

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• Cohesion ? an attraction between molecules of the
  same substance
• Adhesion ? an
• attraction between
• molecules of
• different substances
• Capillary action ? The movement of water against
  gravity, results form cohesion and adhesion

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Why is water so important to life?

• Ice floats
• environment for aquatic organisms, thermal
  insulation
• Resists changes in temperature
• Ex. helps keep us cool, sweating
• Capillarity
• Trees
• Solvent

Water Movement Video
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• Mixture ? a material made up of two or more
  elements or compounds that are mixed together but
  not chemically combined.
• Examples Salt and pepper, Sugar and Sand

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Solutions

• In a solution? all the components are evenly
  distributed throughout
• Example Saltwater
• Solute the substance that is dissolved (salt)
• Solvent the substance in which the solute is
  dissolved (water)
• Concentration is the mass of solute in a given
  volume of solution (the amount of salt in the
  water)

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• Saturated solution ? a solution that cannot
  accept any more solute
• Aqueous solution ? a solution where water is the
  solvent

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Dissociation of Water

• H2O H OH-
• OH- is called the hydroxide ion
• H is called the hydrogen ion

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Acids and Bases

• Acid ? a solution that has more H ions than OH-
  ions
• Tend to have a sour taste
• Examples Lemon juice, tomato juice, stomach
  acid
• Can be corrosive

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• Bases have higher levels of OH- ions than H ions
• Tend to feel slippery
• Tend to have a bitter taste
• Examples Sea Water, Soap, Bleach

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• We measure Acidity and Basic levels using a pH
  scale.
• Ranges from 0 to 14
• 7 is neutral, Acids are below 7, Bases are above
  7
• Buffers ? weak acids or bases that can react with
  strong ones to prevent sharp sudden changes in pH

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Carbon is Cool!

• Carbon is the element essential for life
• Why?
• 1) Can bond with a variety of other elements
  (including itself)
• 2) Can bond with up to 4 other atoms
• 3) Can store a lot of energy in bonds with other
  atoms
• 4) Is versatile (can form a lot of different
  types of molecules), can form multiple bonds
  (double and triple bonds)

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Macromolecules

• Are giant molecules
• Made of monomers ?smallest units of a
  macromolecule
• Polymers? many monomers joined together
• 4 types
• 1) carbohydrates 3) proteins
• 2) lipids 4) Nucleic acids

• Macromolecule Video

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Carbohydrates

• Made up of ? carbon, hydrogen, and oxygen atoms.
• Function ?Used as the main source of energy for
  living things
• Food examples bread, potatoes, pasta, rice,
  cereal, sugar
• Monomers Monosaccharides, single sugar
  molecules.
• Examples
• Glucose ?used for energy
• Galactose ? in milk
• Fructose ? in fruits
• Disaccharides ? 2 monosaccharides hooked together
• Sucrose ? table sugar

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• Polysaccharides ? made up of many monosaccharides
• Examples
• Glycogen ?energy stored in the muscles of animals
• Starch ? provides energy to plants
• Cellulose ? gives structure to plants

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Draw a polysaccharide
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Lipids

• Include Fats, oils, waxes
• Function? energy storage, insulation, biological
  membranes, and waterproof coverings
• Monomers glycerol and fatty acids
• Examples of lipids are olive oil, steroids,
  peanut oil
• Saturated lipids joined by a single bond and
  contain the maximum number of hydrogen atoms.
• Unsaturated lipids contain at least one
  carbon-carbon double bond.

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Triglyceride
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Nucleic Acids

• Contain hydrogen, oxygen, nitrogen, carbon, and
  phosphorus.
• Monomers nucleotides
• 3parts to the nucleotide
• 1) sugar 2) phosphate 3) Nitrogenous base
• Function store and transmit hereditary
  (genetic) information
• There are two types
• -RNA (ribonucleic acid)
• -DNA (deoxyribonucleic acid)

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Proteins

• Examples Fish, eggs, meat
• Functions
• control the rate of reactions and regulate cell
  processes
• Structured and support, form bones and muscles
• Transport
• Lots of others!
• Monomers amino acids
• Represented by
• Polypeptide many amino acids linked together
• Another names for a protein

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Specific examples of proteins

• Hemoglobin? carries oxygen in the blood
• Insulin? regulates blood sugar
• Enzymes ? biological catalysts
• Draw a poly peptide

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Chemical Reactions and Enzymes

• Chemical reaction ? a process where one set of
  chemicals changes into another set
• Reactants ? the elements or compounds that enter
  into a chemical reaction.
• Products ? the elements or compounds produced by
  a chemical reaction.
• CO2 H20 ? H2CO3

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Chemical reactions can be

• Endergonic
• ?Absorb energy and store it for later
• Exergonic
• ?Release energy from food or stored sources
• Endergonic reactions have a net
  __________________ of energy.
• Exergonic reactions have a net __________________
  of energy.

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• Most chemical reactions require the input of some
  energy to get started
• Activation energy ? the energy needed to get a
  reaction started.
• A catalyst ? a substance that speeds up the rate
  of a chemical reaction
• Enzymes are used as biological catalysts

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Enzymes

• 1) Speed up chemical reactions
• 2) Decrease the activation energy needed to get
  chemical reactions started
• 3) provide a site where reactants can be brought
  together to react
• 4) work by the lock and key method
• 5) are substrate specific
• 6) Can be turned on or off

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Enzymes can be affected by

• Temperature
• pH
• Chemicals
• ? Significant changes in any of the above can
  cause the enzyme to become ineffective
• Chemical Reaction Video
• Enzyme Video