Carbon and the Molecular
Diversity of Life
Chapter 4
• Organic molecule - molecule
contains carbon.
• Living things also composed of
other elements (i.e. hydrogen (H),
oxygen (O), nitrogen (N), sulfur (S),
and phosphorus (P))
• Carbon - 6 electrons (2 in first
shell, 4 in second)
• Carbon is therefore likely to form
covalent bonds.
• Carbon chains form skeletons of
most organic molecules.
• Hydrocarbons - organic molecules
that consist of only carbon and
hydrogen atoms.
• Fats - long hydrocarbon tails
attached to a non-hydrocarbon
component.
Examples of carbon bonding
Long hydrocarbon chains
• Isomers - compounds that have
same molecular formula but
different structures and chemical
properties.
• 1Structural isomers - molecules
that have same molecular formula
but are different in structure.
Butane – both are C4H10 but are set up
differently
• 2Geometric isomers - same covalent
bonds but differ in how electrons
are placed.
• Usually double-bonded molecules.
• Because of double bond, molecules
cannot rotate around double bond.
Position of “X” prevents
the rotation of the
molecule.
• 3Enantiomers - mirror images of
each other (like left and right-hand
images)
• There has to be 4 different atoms
attached to carbon for there to be
an enantiomer.
Diagram on left cannot be rotated to match
diagram on right
Functional groups
• Functional groups - groups of
organic molecules most often used
in chemical reactions.
• Arrangement of functional groups
give molecules their uniqueness.
Note difference between
male and female hormone
• 6 functional groups.
• 1Hydroxyl group (-OH) – Polar
covalent bonds - increase solubility
of molecule.
• Contains functional group - alcohol.
• 2Carbonyl group (CO) – Oxygen
atom joined to carbon skeleton by
double bond.
• If it is attached to end of molecule
- aldelhyde.
• If not it is a ketone.
• 3Carboxylic group (COOH) – Acts as
an acid.
• Known as carboxylic acids.
• 4Amino group (NH2) - Acts as base.
• Known as amines.
• 5Sulfhydryl group (SH) – Help
stabilize structure of proteins.
• Known as thiols.
• 6).Phosphate group (PO4) – One
function of this group to transfer
energy between organic molecules.