The Chemistry of Life

1
The Chemistry of Life

• Chapter 2

2
The Nature of Matter

• Matter- anything with mass and volume.
• Matter is made of atoms
• Atoms are small indivisible structures with a
  central nucleus an electron cloud.
• The nucleus has protons and neutrons
• Protons have positive charges mass of 1 AMU
• Neutrons have neutral charges mass of 1 AMU
• The electron cloud is made of electrons traveling
  at the speed of light in designated paths
• Electrons have a negative charge a small mass(0)

3
Elements and Isotopes

• An Element is a substance consisting of one type
  of atom.
• The atomic number is the of protons
• The atomic mass is the of protons and neutrons.
• All atoms have the same of protons and
  electrons.
• Atoms with differing s of neutrons are called
  Isotopes. C-12, C-14
• Some isotopes are radioactive, giving off energy
  and particles.

4
Path of Electrons

• Energy Levels- distance (path) electrons travel
  around the nucleus, energy levels are determined
  by the amount of energy an electron has.
• The 1st energy shape is the s has 2
  electrons
• The 2nd energy shape is the p has 6 electrons
• The 3rd energy shape is the d has 10
  electrons
• The 4th energy shape is the f has 14
  electrons
• Electrons will not fill the next level until all
  the lower levels are filled.
• The periodic chart may be used to determine the
  placement of valance (outer most) electrons.

5
Chemical Compounds

• Elements combine to form compounds
• A Compound is 2 or more elements combined in
  definite proportions.
• Chemical formulas tell you the proportion.
• There are two main types of chemical bonds Ionic
  bonds, Covalent bonds
• The number of valence electrons determines if a
  compound will form.

6
Chemical Bonds

• Ionic bonds occur when valence electrons are
  transferred.
• The transfer of electrons creates charged atoms
  called ions
• Covalent bonds share electrons
• Compounds with covalent bonds are molecules
• There can be single, double, or triple bonds
  depending on the of electrons shared.

7
Special Chemical Bonds

• Van der Waals forces- weak attraction between
  oppositely charged regions of atoms.
• Hydrogen bonds- form between hydrogen and other
  atoms. They are very weak
• Cohesion- is attraction between the same type of
  molecule (Water)
• Adhesion- is attraction between different
  molecules. (capillary action of water)

8
Properties of Water

• Oxygen has a higher electronegativity than
  hydrogen so the electrons spend more time on one
  side of the molecule causing it to be polar.
• Polar molecules have an electrical charge.
• Nonpolar molecules do not have an electrical
  charge.
• Polar nonpolar molecules do not mix. (water and
  oil)

9
Solutions Suspensions

• Mixtures are physically combining two or more
  substances.
• Solutions are mixtures in which the solute is
  dissolved in the solvent.
• Suspensions are mixtures in which materials do
  not dissolve or settle out (blood)

10
Acids, Bases, and pH

• Water will ionize in solution and create H ions
  and OH- ions in equal numbers.
• Acids are substances which produce H ions in
  solution
• Bases are substances which produce OH-
• The pH scale measures amount types of ions.
• 7 is neutral, 1 is a strong acid 14 a strong
  base
• Buffers are weak acids or bases which react with
  strong acids or bases to maintain normal pH.

11
Organic Compounds

• Organic compounds contain carbon
• Carbon is special because it forms up to four
  strong covalent bonds
• Carbon can form chains, rings, or branched
  molecules
• Macromolecules are large covalently bonded
  molecules usually with repeating parts formed by
  polymerization
• Monomers are single molecules
• Polymers are long chains of monomers.
• There are 4 organic compounds carbohydrates,
  lipids, protein, and nucleic acids.

12
Compounds of LifeCarbohydrates

• Carbohydrates- sugars also known as saccharides
• Monosaccharides- simple sugars C6H12O6 Fig. 4-11
• Glucose- plant sugar
• Galactose- found in milk sugar
• Fructose- fruit sugar
• Disaccharides- double sugars
• Dehydration synthesis is linking sugars together
  by removing water
• Sucrose table sugar, glucose fructose
• Maltose malt sugar, glucose glucose
• Lactose milk sugar, glucose galactose

13
Polysaccharides Lipids

• Polysaccharides- many monosaccharides put
  together. Storage form of sugar
• Starch plant storage of sugar
• Glycogen animal storage of sugar
• Cellulose strong rigid polysaccharide
• Hydrolysis is the splitting of sugars by adding
  water.
• Lipids- organic compounds that are waxy or oily
  Fig 4-16
• Lipid Function
• Store energy
• Form membranes
• Chemical messenger

14
Lipids

• Fats Waxes are solids at room temp. and oils
  are liquid at room temperature.
• Lipids are a combination of a glycerol and 3
  Fatty Acids.
• Fatty acid long chain of hydrogen carbon atoms
  with a carboxyl group at one end.
• Carboxyl group a chemical group consisting of
  one carbon atom, one hydrogen atom, and two
  oxygen atoms.
• Glycerol organic alochol
• Saturated and unsaturated lipids Fig. 4-18
• Sterols Phospholipids two other kinds of
  lipids
• Cholesterol is essential to human nutrition.

15
Nucleic Acids

• Large organic molecules composed of C,O,H,N,P
• Nucleotides- individual monomers
• Three basic parts of a nucleotide
• 5 carbon sugar (deoxyribose, or ribose)
• Phosphate group
• Nitrogen containing base (A,T,C,G,U)
• RNA- ribonucleic acid
• DNA- deoxyribonucleic acid
• Nucleic Acids are the genetic keys to life.

16
ProteinsOrganic compounds that contain N,H,C,O

• Amino Acids- composed of an amino group, alpha
  carbon, R group and a carboxyl group.
• There are twenty different R groups
• Peptides- di- tri- peptides consist of two
  three amino acids held together by a peptide
  bond.
• Proteins- contain one or more polypeptide chains.
• very important to life, act as enzymes
• Proteins are shape dependent. Change the shape
  they do not work.

17
Chemical Reactions

• Chemical reactions change the reactants into the
  products.
• Reactants are substances entering the rxn
• Products are produced by the rxn
• Energy determines if a reaction will occur
  spontaneously or if energy must be added.
• Activation energy is the energy used to start a
  reaction.
• A catalyst speeds up a reaction by reducing
  activation energy.

18
Enzymes

• Enzymes are proteins which act as a biological
  catalysts
• Enzymes lower activation energy by placing
  molecules in position to react.
• Substrates the reactants affected by the enzyme.
• Substrates bind to the active site (shape)
• Enzymes are not used up in a reaction
• Enzymes only work at particular pH and
  temperatures because of their shape.