Chemistry of Life

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Chemistry of Life

• Chemistry is the study of how matter interacts,
  thus we need to understand some of the basic
  rules and ideas about matter to understand how
  living things work.

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Vocabulary
Element - substance that cannot be separated
into simpler substances by
chemical means. 92 occur naturally 13
made by humans Compound - combination of two or
more elements
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Life Elements

• Typical living thing composed (99.9 wt) of six
  elements
• C, H, N, O, P, and S.
• Seventeen other elements occur in minute
  quantities or as traces.

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Vocabulary
Atoms - smallest particle into which an element
can be divided and still have the properties of
that element. Molecule - two or more atoms
joined together by molecular bonds.
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Atom Organization
Sub-atomic particle charge Wt. (amu) location
proton 1 Nucleus
neutron none 1 Nucleus
electron - 0 Orbit nucleus
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Formulas
Atomic Number protons Note "normal" atom
the number of electrons
number of protons (atom has no net charge)
Atomic Wt (Mass) protons neutrons
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Atomic Variants

• 1. Isotopes - differ in the number of neutrons
  in the nucleus, thus changing wt. of element.
• 2. Ions - number of electrons differs from the
  number of protons, thus giving element net
  negative or a net positive.

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Electrons In Orbit

• Number electrons in outer-most energy level gives
  each atom its unique chemical behavior.
• (E.g) H is an odorless gas C is a black powdery
  substance.

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Electrons In Orbit

• Maximum number electrons / orbital determined
  by the formula
• X 2N2
• (where X maximum number of electrons
• in energy level number N).

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ATOMIC STRUCTURE
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MOLECULAR BONDS two or more atoms bonded
together by energy links
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Types of Molecular Bonds

• type of bond
• occurs when two or more atoms share
• a pair of electrons (may be single,
  
• double, or triple bonds)
• a. Polar Covalent un-equal sharing of elec.
  
• pair
• b. Non-Polar Covalent elec. pair
  equally
• 
  shared

• Covalent Bonds-
• Most common type
• occurs when two or more atoms share pair elec.
• may form single, double, or triple bonds
• POLAR COVALENT un-equal sharing of elec
• NON-POLAR COVALENT elec pair equally
• 
  shared

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2. Hydrogen Bond

• bond between the negative pole of a polar
  molecule and the slight positive charge on a
  hydrogen atom that is participating in another
  polar molecule.
• weakest

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3. Ionic Bonds

• a complete transfer of electrons from one
  molecule to another. It is most common when one
  molecule needs just one or two to complete its
  outermost shell and the other has only one or two
  in its outermost shell.

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Properties of Water

• High Specific Heat - takes 1 calorie (a unit of
  heat energy) to raise the temperature of one gram
  of water 1o Centigrade.
• keeps environment of cells constant
• High Heat of Vaporization - takes 540 calories of
  heat to change 1 gram of liquid water at 100o C
  to 1 gram of water vapor at 100o C
• sweating can help to cool organisms

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Properties of Water

• High degree Cohesion Adhesion capillary
  action
• plants use this to draw water against
  gravity
• High Surface Tension - tendency of molecules at
  the surface of a liquid to cohere to each other
  and not to the air above.
• some insects use this to walk on water!
• Ice floats - Ice is less dense than liquid water
  and hence floats (WHY??)
• allows fish and other organisms to survive
  winter

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Properties of Water

• Universal Solvent - dissolves ionic most polar
  substances
• excellent medium for cytoplasm!
• Solvent that which dissolves another
• Solute that which is dissolved
• Solution solvent solute
• Hydrophilic ("water-loving") substances readily
  dissolve in water
• while hydrophobic ("water-fearing") substances do
  not dissolve
• in water.

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Properties of Water

• Water Dissociation- slight tendency to fall apart
  (dissociate)
• into hydrogen ions (H) and hydroxide ions
  (OH-).
• An Acid is a substance that gives off hydrogen
  ions when dissolved
• in water.
• A Base is a substance that accepts hydrogen ions
• (thereby increasing the hydroxide ions).
• PH Scale 0_______________7___________________1
  4
• Acids Neutral
  Bases
• Highest H conc. Lowest
  H conc.

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4 Classes of Organic Molecules

• Proteins
• Carbohydrates
• Lipids
• Nucleic Acids

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Functions of Proteins

• Structural proteins - form cell parts
• 2. Regulatory proteins - control cell processes
• 3. Enzymes - facilitate (help) many chemical
  reactions they
• do this by lowering the
  amount of energy needed
• to start the reaction the
  enzyme is not
• permanently altered in the
  process.
• 4. Hormones - chemical messengers
• 5. Transport proteins - carry other substances
  around cells
• or from cell to cell.

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Carbohydrates

• Most abundant types organic molecules
• Function energy sources structural
  components
• monomers of carbohydrates isomers of C6H12O6

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3 Major Categories Carbohydrates

• Monosaccharides
• Disaccharides
• Polysaccharides

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Lipids

• Fats, oils, waxes, steroids, phospholipids.
• Function energy storage, waterproof coatings,
  chemical messengers.
• Three categories of lipids
• Triglycerides (saturated unsaturated fats)
• Waxes
• Phospholipids
• Steroids

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Nucleic Acids

• Nucleic Acids - Large molecules
• carry coded genetic information
• Polymers of nucleotides (monomer)
• Two main types
• Deoxyribonucleic acid (DNA)
• Double helix of anti-parallel nucleotide chains
• Ribonucleic acid (RNA)
• Single nucleotide chain