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Carbohydrates Lipids
Elements
Examples
carbon, hydrogen,
and oxygen
sugars, starchj
and cellulose
carbon, oxygen,
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hydrogen, and
pliosphorus'
carbon, oxygen,
hydrogen, nitrogen,
carbon, oxygen,
hydrogen, nitrogen,
and sulfur
and lÿhosphorus
fats, oils, waxes,
enzymes, skin,
DNA and RNA
p.hospholipids, and
and hair
cholesterol
Function
supply energyfor
cell processes; form
plant structures;
short-term energy.
store large amounts
of energy long term;
form boundaries
around cells
regulate cell
processes and
build cell structures
carry hereditary
information; used
to make proteins
. storage.
IrlaIic #omlo nls
.You and all tying things are made up of compounds that are
classified as organic or inorganic. Rocks and other nonliving
things contain inorganic compounds, but m6st do not conÿlarge amounts of organic compounds. Organic compounds
always contain carbon and hyd.rogen and usually are associated
with living tkings. One exception would be nonliving things that
are products of living things. For example, coaI co ntÿiins organic
compounds because it was formed from dead and decaying
plants. Organic moleculescan contain hundxeds or even thousands of atoms that can be arranged in many ways. Table 3 compares the fore" groups o"f orgai4Ac compounds that maize up all
living things--carbohy&ates, lipids, proteins, and nudeic adds.
Carbohydrates Carbohydrates are organic molecules thaÿ
supply energy for cell processes[ Sugars and starches are' carbohydrates "that cells use for energy. Some carbohydrates also are
important parts of cell structures. For ÿample, a carbohydrate
ca]ied cellulose is an important part of plant cells.
: Lipids Another type of organic compound foimd in Icing
i
i things is a lipid. Lipids do not mix ÿith water. Lipids such as fats
: and oils store and release even larger amounts of energy than
:" carbohydrates
do. One type of lipid, the phospholipid, is a
major part of cellmembranes.
72 ÷ A CI6ÿPTEII Cell Processes
Proteins Organic compounds called proteins have many
important functions in living organisms. They are made up of
smaller molecules called amino adds. Proteins are the building
i
blocks of many stamctures in organisms. Youÿ musdes contain
large amounts of protein. Proteins are scattered throughout cell
membranes. Certain proteins called enzymes regulate nearly all
chemical reactions in cdls.
NU¢iÿ[¢ Acids Large organic molecules that store important
,
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coded information in ce!ls are called nucleic adds. One nucleic
acid, deoxyribonucleic add, or DNA--genetic material is fmmd
in all cells. It carries information that directs each cell's activities.
Another nucleic acid, ribonucleic add, or RNA, is needed to make
enzymes and other proteinsl
Hnorgani¢ ¢ompouad÷
Most inorganic compounds are made from dements other
than carbon. Genera11ÿ inorganic molecules contain fewer atoms
than organic molecules. Inorganic compounds are the source fqr
many elements needed by living things. Iaor example, plants taÿe
up inorganic compounds from the soil. Thesÿ inorganid compounds can contain the dements nitrogen, phosplÿorus, and sulfur. Many foods that you eat contain inorganic compounds.
Table 4 shows some of the inorganic compounds that axe important to you. One of the most important inorganic compounds
for living things is water.
Cakium pl{osphate
gives strength to bones ,
Hydrochloric.add
breaks' down foods in the stomach
'Sodium bicarÿaonate
helps the dig eÿ-tion of food to occur
Salts containing sodium, important in sending
chlorine, and potassium messages along nerves
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SECTION 1 Chemistry of Life A .÷ 73