Chapter 4 – Carbon Chemistry
Section 1: Properties of Carbon
• Because of its unique ability to
combine in many ways with itself and
other elements, carbon has a central
role in the chemistry of living
organisms
Carbon Atoms and Bonding
• Carbon atoms can form single, double or
triple bonds with other carbon atoms.
• Carbon can form up to 4 bonds
• This allows carbon atoms to form long
chains, almost unlimited in length.
• Carbon can bond with other carbons, form
straight chains, branched chains and rings
The Chemistry of Carbon
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“organic”: must contain at least one carbon. CH4 = simplest organic molecule
Carbon has 4 valence electrons
Therefore, carbon will always make 4 bonds with other atoms
Ability to form millions of different compounds with other elements
Forms of Pure Carbon
• Diamond, graphite, fullerenes and
nanotubes are four forms of the element
carbon
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https://www.youtube.com/watch?v=heNhJmKAozw
(How diamonds are made)
• Diamond – crystalline form of carbon in
which each carbon atom is bonded strongly
to four other carbon atoms
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Formed from high temps and pressure
Melting point is more than 3500 C
Can be made artificially and are used in industry as cutting tools
Forms of Pure Carbon
• Graphite – each carbon atom is bonded tightly to
three other carbon atoms in flat layers
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Bonds are very weak
“Lead” in pencils is mostly graphite
Used as a lubricant in machines
Forms of Pure Carbon
• Fullerenes – consists of carbon atoms
arranged in the shape of a hollow sphere
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Called buckyballs after an architect
• Nanotube – carbon atoms are arranged in
the shape of a long hollow cylinder
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Tiny, light, flexible and extremely strong
Good conductors of heat and electricity.
Chapter 4 – Carbon Chemistry
Section 2 – Carbon Compounds
Organic Compounds
• Organic compounds – compounds that contain carbon
• Many organic compounds have similar properties in terms of
melting and boiling points, odor, electrical conductivity and
solubility
• Many are gases at room temperature
• Many have a strong odor
• Many do not dissolve in water
Hydrocarbons
• Hydrocarbon – compound that contains
only the elements carbon and hydrogen
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Hydrocarbons mix poorly with water
All hydrocarbons are flammable; CH4 (methane), C2H6 (ethane), C3H8
(propane)
Structure of Hydrocarbons
• The carbon chains in the hydrocarbon may be straight, branched or
ring-shaped
• Structural formula – shows the kind, number and arrangement of
atoms in a molecule
• Isomer – compounds that have the same chemical formula but
different structural formulas which makes them have different
properties
C4H10
Structure of Hydrocarbons
• Saturated hydrocarbons – only single bonds, has maximum
number a hydrogen atoms attached
• Unsaturated hydrocarbons – has double or triple bonds, have
fewer hydrogen than saturated hydrocarbons
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Structure of Hydrocarbons
Substituted hydrocarbon – atoms of other elements replace one or more
hydrogen atoms in a hydrocarbon
Include halogen-containing compounds, alcohols, and organic compounds
Alcohol – a substituted hydrocarbon that contains one or more hydroxyl
groups
• hydroxyl group –OH
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Alcohols dissolve well in water,
have higher boiling points than other
Hydrocarbons with similar numbers of
carbon
• Organic acid – a substituted hydrocarbon that contains
one or more carboxyl groups
• Example: citric acid (lemons) acetic acid (vinegar), malic
acid (apples), butyric acid (butter)
• carboxyl group –COOH
• Ester – compound made by chemically combining an
alcohol and an organic acid
• Have pleasant, fruity smells
• Responsible for smells of pineapple, bananas,
strawberries
Polymers
• Polymer – large molecule made of a chain
of many smaller molecules bonded
together
• Monomer – smaller molecules that make
up polymers
Section 3– Life with Carbon
There are 4 classes of organic compounds required by all living things
called macromolecules.
Foods provide these organic compounds which cells of living things use,
change, and store
These 4 classes are nutrients-substances that provide the energy and
raw materials the body needs to grow, repair worn parts, and function
properly.
The Four Macromolecules of Life
Macromolecule (polymer) made by joining many monomers (single
unit)
Polymerization: chemical rxn which joins monomers to make polymers
The four main classes of biological molecules:
1. Carbohydrates (sugar, starches, cellulose)
2. Lipids (wax, fats, oils, steroids)
3. Proteins (muscle, hair, hormones, enzymes)
4. Nucleic acids (DNA and RNA)
Carbohydrates
• Carbohydrate – an energy-rich organic compound made of
the elements carbon, hydrogen and oxygen
• Simple carbohydrate – the simplest carbs are sugars (glucose
is in your body – C6H12O6)
• Complex carbohydrate – a polymer made of smaller
molecules that are simple carbs bonded to one another
CARBOHYDRATES: Monomer = Monosaccharide
•Contain C, H, and O in a 1:2:1 ratio
•Most end with “ose”
•An animal’s main energy source
•Carbs are burned first in the body
•Monosaccharides: (C6H12O6):
glucose, fructose, galactose
•Disaccharides:
sucrose, lactose, maltose
•Polysaccharides: (complex carbohydrates)
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A) glycogen (carb storage animal liver)
B) starch (carb storage in plants)
C) cellulose (cell walls, cotton) “roughage”
D) chitin (exoskeletons of arthropods)
Proteins
• Proteins – formed from smaller
molecules called amino acids
• Amino acid – a monomer that is a
building block of proteins
• Each amino acid molecule has a
carboxyl group (–COOH) and an amino
group (–NH3)
• The body uses proteins from food to
build and repair body parts and to
regulate cell activities
PROTEINS: Monomer = Amino Acid
• essential to the structures and
activities of life
• Contain C, H, O, N (S, P)
• 50% of your dry weight
• examples of groups of proteins:
1. enzymes (amylase, sucrase,
maltase, lactase)
2. structural (collagen, elastin)
3. contractile (actin, myosin)
4. transport (hemoglobin, protein
channels)
5. hormones (insulin)
AMINO ACID: Structure
Each amino acid has:
•An amino group (-NH2)
•A carboxyl group (COOH)
•An R group, which distinguishes
each of the 20 different amino
acids
* Each amino acid has
specific properties
based on the R-group
* Peptide bonds link
amino acids together 
polypeptide (protein)
Lipids
• Lipids – energy-rich compounds made of carbon, oxygen and
hydrogen
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Lipids include fats, oils, waxes and cholesterol
• Gram for gram, lipids release twice as much energy in your
body as do carbohydrates
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Fatty acids – organic
compound that is a monomer
of a fat or oil
Cholesterol – a waxy lipid in
animal cells
LIPIDS: Monomer = Fatty Acids
* Mostly C and H atoms linked by
nonpolar covalent bonds
* reserve energy-storage molecules
(burned after carbs are gone)
* Insoluble in water (polar)
* Soluble in nonpolar solvents (ether)
* More energy in lipids than in carbs
- 9 cal/g Lipid vs. 4 cal/g Carb
* Examples: triglycerides, phospholipids,
steroids (cholesterol), waxes, oils, fats
* Triglyceride = 3 fatty acids + 1 glycerol
* Saturated Fats: all single bonds in chain
- solid at room temp (ex: butter, lard)
* Unsaturated fats: one or more C=C bond in
chain
- liquid at room temp (ex: all oils)
Nucleic Acids
• Nucleic acids – very large organic molecules made up of
carbon, oxygen, hydrogen, nitrogen and phosphorus
• Two types – DNA and RNA
• Elements that make up all living things…
• C – Carbon
• H – Hydrogen
• N – Nitrogen
• O – Oxygen
• P – Phosphorus
• S – Sulfur
NUCLEIC ACIDS: Monomer = Nucleotide
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Nucleic acids (DNA and RNA) store and transmit genetic information
DNA = Deoxyribonucleic acid
RNA = Ribonucleic acid
Large macromolecules containing C, H, O, N, P
• One nucleotide = 5-carbon sugar, phosphate (PO4-), nitrogenous base
The sugars and phosphates are
the backbone for the nucleic
acid
DNA’s sugar = deoxyribose
RNA’s sugar = ribose
Other Compounds in Foods
• Vitamins-organic compounds that serve as
helper molecules in a variety of chemical
reactions in your body.
• Minerals-elements in the form of ions in your
body.
• Water-makes up most of your body’s fluids.