Chapter 4: Carbon and the Molecular Diversity of Life
 Overview: Carbon: The Backbone of Life
• Although cells are 70–95% water, the rest consists mostly of ___________
______________________
• Carbon is _______________ in its _________________________________
_____________________________
• Proteins, DNA, carbohydrates, and other molecules that distinguish living matter are
all _________________________________
 Concept 4.1: Organic chemistry is the study of carbon compounds
• ______________________ is the study of compounds that contain carbon
• Organic compounds range from simple molecules like (CH4), to colossal ones (like
most proteins)
• Most organic compounds contain __________ atoms in addition to carbon
• The major elements of life include: ________________---their overall percentages
are uniform from one organism to the next.
• _____________, the idea that organic compounds arise only in organisms, was
________________ when chemists synthesized these compounds
• __________________ is the view that all natural phenomena including the processes
of life are governed by physical and chemical laws
– ____________________________________ helps to support this belief
– The foundation of organic chemistry is not some intangible life force, but the
unique chemical versatility of the element carbon
 Concept 4.2: Carbon atoms can form diverse molecules by bonding to four other
atoms
• __________________________ is the key to an atom’s characteristics
• Electron configuration determines the ___________________________ an atom will
form with other atoms
• With four valence electrons (unpaired outer shell electrons), carbon can form
_______________________________ with a variety of atoms
• This ____________________ makes large, complex molecules possible
• In molecules with multiple carbons, each carbon bonded to four other atoms has a
__________________________
• However, when two carbon atoms are joined by a __________________, the
molecule has a _____________________
• The electron configuration of carbon gives it covalent compatibility with
______________________________
• The valences of carbon and its most frequent partners (hydrogen, oxygen, and
nitrogen) are the “_______________________” that governs the architecture of
living molecules
• These are carbon’s most frequent partners and their valence numbers.
These are the four major atomic components of organic molecules:
• Carbon atoms can partner with atoms other than hydrogen; for example:
– Carbon dioxide: CO
2
– Urea: CO(NH )
2 2
• Molecular Diversity Arising from Carbon Skeleton Variation
– __________________ form the skeletons of most organic molecules
– Carbon chains vary in _________________________
• They may be straight, branched, or arranged in closed rings.
• Some may have double bonds which vary in number and location.
• All of these carbon skeletons represent hydrocarbons (organic
molecules consisting only of carbon and hydrogen). Notice the diversity
of the carbon skeleton.
• Hydrocarbons
– ___________________ are organic molecules consisting of only carbon and
hydrogen
– They are the major components of _____________________
– Many organic molecules have hydrocarbon components. Fats, for example,
have long hydrocarbon tails. This gives them similar properties to petroleum.
• Neither dissolves in water; both are hydrophobic
• Hydrocarbons can undergo reactions that release a large amount of
energy (ex: gasoline as fuels for cars; fat as fuel for animals)
• Isomers
– __________________ are compounds with the same molecular formula but
different structures and properties:
• _____________________ have different covalent arrangements of their
atoms
• _____________________ have the same covalent arrangements but
differ in spatial arrangements
• ______________________are isomers that are mirror images of each
other
– Examples of Each:
Structural Isomers
Geometric Isomers
Enantiomers
– Enantiomers are important in the _________________________
– Two enantiomers of a drug may have different effects.
Ex: ________________________
– Differing effects of enantiomers demonstrate that organisms are sensitive to
even subtle variations in molecules
 Concept 4.3: A small number of chemical groups are key to the functioning of
biological molecules
• Distinctive properties of organic molecules depend not only on the carbon skeleton
but also on the ________________________________________
• A ______________________________ are often attached to skeletons of organic
molecules
• The Chemical Groups Most Important in the Processes of Life
– _____________________ are the components of organic molecules that are
most commonly involved in _________________________
– The ____________________________ of functional groups give each molecule
its unique properties
– The ___________________________ that are _________________ in the
chemistry of life:
• Hydroxyl group _____________
• Carbonyl group _____________
• Carboxyl group _____________
• Amino group _____________
• Sulfhydryl group ____________
• Phosphate group ____________
• Methyl group _______________
 ATP: An Important Source of Energy for Cellular Processes
• One phosphate molecule, __________________________________, is the primary
energy-transferring molecule in the cell
• _______ consists of an organic molecule called adenosine attached to a string of
________________________
• One phosphate may be split off as a result of ATP’s reaction with water. ATP
becomes ADP (adenosine diphosphate) and the reaction releases energy that can be
used by the cell.
You should now be able to:
1.
2.
3.
4.
5.
Explain how carbon’s electron configuration explains its ability to form large, complex, diverse organic molecules
Describe how carbon skeletons may vary and explain how this variation contributes to the diversity and complexity of
organic molecules
Distinguish among the three types of isomers: structural, geometric, and enantiomer
Name the major functional groups found in organic molecules; describe the basic structure of each functional group and
outline the chemical properties of the organic molecules in which they occur
Explain how ATP functions as the primary energy transfer molecule in living cells