CARBON AS A BASIS FOR LIFE Chapter 4
Dec 29, 2015
THE IMPORTANCE OF CARBON
All living organisms based significantly on carbon
Creates a large diversity of biological molecules Includes: proteins, DNA, carbohydrates, lipids, and
others Distinguishes living form nonliving matter
All these molecules are examples of emergent properties
DEFINING ORGANIC CHEMISTRY
Organic compounds are anything containing carbon Hydrocarbon molecules contain only hydrogen
and carbon Simple (CH4) to large and diverse (proteins)
Organic molecule variation exists both w/i individual species and b/w different species
The four main elements of living organisms are? (hint: 96% of the human body) Valence is the number of covalent bonds an
atom can make Valence electrons are ALL electrons in
outermost shell
CARBON’S ABILITY TO BOND 6 electrons, ? in first shell and ? in outer
shell Can donate or accept electrons equally (form an
ion) Usually shares (covalent bonds)
Single, double, or triple
Makes large, complex molecules possible Each line between 2 atoms represents 2
shared electrons
CARBON CARBON BONDING
Skeletons of most organic compounds are carbon chains Straight, branched, or ringed Number and bond type vary
Examples of hydrocarbons
HYDROCARBONS
What constitutes a hydrocarbon? Main components of fossil fuels b/c come
from decomposed living organisms Not major component of living organisms,
but are regions in other molecules Reactions cause large amounts of energy release
Fats – long, nonpolar, hydrophobic tail Serve as stored fuel in animals
Used in gasoline
ISOMERS 2 molecules with the same # of the same atoms,
but different structure = different properties 3 types
Structural Covalently bonded and arranged in different orders Number of configurations increase with increase in number of
carbons Geometric
Covalently the same partners, but different spatial arrangement Double bonds prohibit rotation
Enantiomer Mirror images (R- and L-)
Usually one is inactive Important in pharmaceuticals because both can have different
effects
ISOMER EXAMPLES
Geometric Isomer
Enantiomer
Structural Isomer
4C’s and 8H’s
1 of each
2C’s, 2H’s, and 2 Cl’s
Cl ClCl
Cl
BIOMOLECULAR FUNCTIONING Hydrogens can be replaced by other atom
groupings Arrangement determines properties
May participate directly in reactions or indirectly because of shape
Sex hormones as an example Testosterone vs estradiol
Different actions Minimal differences in structure