Biology : The Chemistry of Life Ch'2

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Biology The Chemistry of Life Ch.2

• All things are composed of atoms.
• The periodic table organizes all known atoms( 112
  or so)
• Most atoms are not stable and gain or lose
  electrons and form bonds and compounds.
• About 25 atoms or elements are essential for
  living organisms

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Atoms or Elements in Living Things

• Oxygen (O) - 65 Iron(Fe) - trace
• Carbon (C) 18.5 Iodine(I) - trace
• Hydrogen (H)-9.5 Copper(Cu) - trace
• Nitrogen (N) 3.3 Manganese(Mn) trace
• Calcium (Ca) 1.5 Molybdenum(Mo) trace
• Phosphorus(P) 1 Cobalt(Co) - trace
• Potassium(K) - .4 Boron (B) - trace
• Sulfur(S) - .3 Zinc (Zn) - trace
• Magnesium (Mg) - .1 Fluorine (F) - trace

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Compounds and Bonding

• Atoms which are unstable will transfer or share
  electrons with other atoms to form a more stable
  compound. This is termed a chemical bond, and in
  this bond is stored energy.
• If electrons are shared between two or more atoms
  it is termed a covalent bond

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Covalent Bonds

• In general when nonmetals combine with each other
  they share electrons to gain a stable outer
  electron level.
• Example of covalent bonds H2O, CO2, C6H12O6

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Ionic Bonds

• When an atom gains or loses electrons to become a
  stable ion there is a net attraction between the
  two atoms. This bond is termed an ionic bond,
  and generally will occur between a metal and a
  nonmetal
• Ex. NaCl , CaCl2

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Bonding Generalities

• When a metal is present in a compound you
  probably have an ionic bond.
• When no metals are present you probably have a
  covalent bond
• Most matter is found in compounds, with energy
  locked in the bonds.

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Overall Story

• Most atoms are not stable as a result of their
  electron arrangement.
• Atoms will share, gain or lose electrons to have
  a stable electron arrangement(0-8)
• When atoms share, gain or lose electrons chemical
  bonds (ionic or covalent) occur. This process
  allows for energy stability in matter.

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Mixtures and Solutions

• Matter is found as
• Elements
• Compounds
• Mixtures (solutions)

Mixture of elements and compounds
Element
compound
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Mixtures

• Mixtures are always made from two or more
  elements or compounds combined. If the mixture
  is even we call it a solution or a homogeneous
  mixture. If the mixture is not uniform, we call
  it a heterogeneous mixture

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2.2 Water and Solutions

• Water is essential to most organisms
• Water
• Serves as a means of transport
• Is the universal solvent
• Composes 70-95 of most organisms
• Is covalently bonded Hydrogen and Oxygen
• Is a polar molecule(unequal distribution of
  charges)

H2O
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Water Polar Molecule

• Since water is polar and has () and (-) charged
  sides, it will attract other water molecules, and
  dissolve ionic compounds.
• When water molecules bond to each other it is
  termed a hydrogen bond.

Hydrogen bond
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Properties of Water

• Water has strong cohesive forces which keep
  molecules together.
• These forces tend to keep water in drops.
• Water molecules are also attracted to other
  substances. The attraction of water to other
  substances is termed its adhesion

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Aqueous Solutions

• Many different substances can be added to water
  to make an aqueous solution.
• Since water is polar, other polar and ionic
  substances can be easily dissolved in it to make
  a solution.

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Acids and Bases

• All liquids can be measured for how many Hydrogen
  ions (H), and Hydroxide ions (OH-) are in them.
  Since most liquids involve something dissolved in
  water there are always hydrogen and hydroxide
  ions present. A scale is used to compare the
  amount of Hydrogen ions to Hydroxide ions. This
  is termed the pH scale. If the amount of
  Hydrogen and Hydroxide ions are equal the liquid
  has a pH of 7, or neutral. If the liquid has
  more Hydrogen ions than Hydroxide ions the liquid
  is considered an acid. If there are more
  Hydroxide ions in the liquid than Hydrogen ions
  the liquid is a base.

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Acids / Bases

• Both Hydrogen ions and Hydroxide ions are
  corrosive and dangerous to living organisms.
• What do people do if their gastric (stomach)
  juice becomes too acidic?

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2.3 Chemistry of Cells

• Most matter in living organisms is water as well
  as organic compounds
• Organic compounds contain carbon.
• These compounds are carbohydrates, proteins,
  lipids, and nucleic acid.

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Life Substances (Biochemistry)

• Carbon is an important element to all living
  things.
• Carbon has four electrons in its outer level and
  can do the following
• Covalently bond with other carbons to form
  chains, rings, and branched chains
• Readily bond with hydrogen and oxygen
• Form single, double, or triple bonds with itself
  and other atoms.

Benzene ring
Propane
Glucose
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Polymers Large molecule made from small monomers

• Huge molecules such as proteins are composed of
  smaller units bonded together. Like the cars of
  a train small monomers are bonded together to
  make large polymers.
• Polymers can also be broken down into their
  monomers.
• Examples proteins, starches, and fats are
  polymers

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Carbohydrates Sugars and Starches

• Carbohydrates composed of carbon,hydrogen,and
  oxygen atoms covalently bonded.
• Carbohydrates have about twice as many hydrogen
  atoms as oxygen.
• Sugars and starches are carbohydrates

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Sugars

• Monosaccharide simple sugar (monomer) C6H12O6
• glucose, fructose
• Disaccharide two monosaccharides bonded
  together
• sucrose C12H22O11

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Polysaccharides Starch, Cellulose, Glycogen

• Polysaccharides are composed of three or more
  monomers. Monomers are the simple sugars
  glucose, galactose, fructose, etc.
• Starches are polysaccharides which are highly
  branched chains of glucose. Plants use starches
  as food storage

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Polysaccharides Cont

• Glycogen used for animal food storage, similar to
  starch with more branching of glucose monomers
• Cellulose glucose monomers bonded like a chain
  link fence, found in the cell walls of plants and
  gives support. (Paper)

Glycogen glucose monomers
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Polysaccharides Cellulose

• Cellulose is composed of glucose monomers and is
  found in cell walls, humans cant break this
  compound down into its monomers, but cows,
  horses, and other grazers can.

Glucose monomers
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Lipids Fats and Oils

• Lipids are organic(carbon based) compounds that
  have a large amount of C-H bonds and less Oxygen
  than carbohydrates.
• Fats are lipids solid at room temperature.
• Oils are lipids that are liquid at room
  temperature.
• Lipids are insoluble in water, and are used for
  energy storage, insulation and protection.

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Lipids Cont

• If all carbon in a lipid are single bonds
  (sharing two electrons) the lipid is considered
  saturated.
• If there is a double carbon bond in a lipid the
  molecule is considered unsaturated

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Fatty Acids Glycerol

• Glycerol is a three carbon molecule that serves
  as a backbone for the lipid molecule. Attached
  to the glycerol are three fatty acid chains.
  Three chains on a glycerol is termed
  triglycerides.

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Proteins

• Proteins are polymers composed of amino acids.
  Proteins have the elements C,O,H,N, and sometimes
  S.
• There are 20 different amino acid monomers which
  are linked together to form a protein. It
  requires hundreds of amino acids to bond to form
  a protein

An amino acid
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Proteins Cont..

• Amino acids are bonded together to form proteins.
  This bond between amino acids is called a
  peptide bond. This bond is between a Carbon atom
  and a Nitrogen atom. To form this bond a H and
  OH are removed from an amino acid. Water is
  formed when a peptide bond forms.

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Nucleic Acids

• Nucleic acid is a complex, large molecule which
  stores the genetic code of life
• DNA deoxyribonucleic acid
• RNA- ribonucleic acid
• Nucleic Acids have
• Phosphate group
• Sugar
• Nitrogen base

Nitrogen base
Phosphate group
sugar
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2.4 Energy and Chemical Reactions

• Chemical reactions occur when bonds between
  compounds are broken or formed. Energy is locked
  in chemical bonds which may be released as light,
  heat, or other forms of energy
• All the chemical bond breaking within an organism
  is called that organisms metabolism

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Enzymes

• Enzymes are important proteins found in living
  things.
• Enzymes are specific to a substrate (substance
  and enzyme works on)
• Enzymes
• Cause chemical reactions
• Speed up chemical reactions
• Synthesis of molecules

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Enzyme Action

• An enzyme attaches to its substrate.
• The enzyme causes a reaction to occur(break down
  a compound, etc.)
• The reaction is complete, and the enzyme goes to
  another substrate.

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Writing Chemical Reactions

• When writing chemical equations to describe
  reactions the reactants are on the left, with an
  arrow, and then the products of the reaction.

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End of Ch. 2 Notes

• Read your text and know the vocabulary words.
• Ask questions and get help if youre confused.