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Chapter 3
Biochemistry
I. Carbon Compounds
 Inorganic vs.
Organic
 Inorganic
compounds do not
contain carbon
atoms
 Organic
compounds contain
carbon atoms
Carbon Bonding
 Carbon has 4 electrons in its
outer shell
 It wants to gain 4 more to
become stable with 8
 Carbon readily forms four
covalent bonds with atoms of
other elements
 Carbon is unique from other
elements because it can bond
with other carbon atoms
 Because of all the preceding,
carbon is able to form an
enormous variety of organic
bonds
 Single Bond-sharing one pair
of electrons
 Double Bond-sharing two pair
of electrons
 Triple Bond-sharing three pair
of electrons
Functional Groups
 Clusters of atoms that
influence the properties or
characteristics of the
molecule
Large Carbon Molecules
 Monomers- a simple molecule, smallest subunit
 Polymers- made of repeating monomers
 Macromolecules- made up of large polymers
You Down with ATP?
 Cells run on energy in the form of
ATP
 Adenosine triphosphate
 Phosphate groups attached by
covalent bonds, which store high
amounts of energy
II. Molecules of Life
 Carbohydrates
 Lipids
 Proteins
 Nucleic Acids
Carbohydrates
 Composed of carbon, hydrogen, and
oxygen in a ratio of 1C:2H:1O, Serve as a
source of energy or used for structural
materials
 Monosaccharides- a monomer of a
carbohydrate (glucose, fructose and
galactose)
 Disaccharides- two monosaccharides or a
double sugar (glucose + fructose = sucrose)
 Polysaccharides- three or more
monosaccharides
 Animals store glucose in the form of the polysaccharide
glycogen
 Plants store glucose as the polysaccharide starch
 Strength and rigidity in plants is caused by the structure of the
polysaccharide cellulose
Proteins
 Composed mainly of carbon,
hydrogen, oxygen, and nitrogen,
provide structure for cells
 Amino acids-monomers of protein
(building blocks)
 Dipeptides-two amino acids held
together by a peptide bond
 Polypeptides- three or more amino
acids, held together by peptide
bonds
Amino Acids
 20 different amino acids
 All contain
 Central carbon
 Amino group
 A carboxyl group (COOH)
 A single hydrogen
 R group (the only thing different between
the 20 amino acids) influences the
properties of the amino acid
Peptide Bond
 Covalent bond linking two amino acids
 A condensation reaction (water is formed and
released)
 Long chains of amino acids has positive and negative
regions which fold to give protein molecules unique
shapes
 The shapes can be denatured when heated
Enzymes
RNA or protein
molecules that
act as
biological
catalysts
Depend on the
fit between
Substrate
Enzymes active
site
Lipids
 Long chains of carbon with many hydrogens
 Function is to store energy
 Include: fatty acids, triglycerides, phospholipids,
waxes, steroids
Fatty Acids
 Unbranched carbon chains that
make up most lipids
 Long chain of carbon with a carboxyl
group at one end
 Carboxyl end is polar and therefore
hydrophilic
 Hydrocarbon end is nonpolar and
therefore hydrophobic
 Fatty acids include triglycerides,
phospholipids, and waxes
Saturated Fatty Acids
Carbon atoms fully saturated with hydrogens
Unsaturated Fatty Acids
Carbon atoms with double bonds
Triglycerides
 3 molecules of a fatty
acid joined to one
molecule of the alcohol
glycerol
 Saturated triglycerides
have high melting
points and are hard at
room temp (butter and
fats in red meat)
 Unsaturated are usually
soft or liquid at room
temp and found in
plant seeds (olive oil)
Phospholipids
 Two fatty acids attached to a molecule of
glycerol and a phosphate group attached to
the third carbon of the glycerol
 Help make up the cell membrane
 Lipid bilayer
 Hydrophobic head
 Hydrophilic tail
Waxes
A long fatty acid
chain connected
to a long alcohol
chain
Waterproof
Help form
protective coating
in plants and
animals (earwax)
Steroids
Four fused carbon
rings with various
functional groups
Hormones
Cholesterol
Nucleic Acids
DNA
Contains information that determines the
characteristics of an organism and directs cell
activities
RNA
Stores and transfer information of DNA to
make proteins
Composed of nucleotides
Sugar
Phosphate
Base
Review
 What do all organic compounds contain?
 Carbon
How many electrons are
shared in a double bond?
 4 electrons (aka 2 pair)
How many
electrons does
carbon want to
gain?
 4 electrons
What is the
smallest subunit
 Monomer
 What is the monomer of
carbohydrates?
 monosaccharides
 What is the monomer of
proteins?
 Amino acid
 How do animals store
glucose?
 Glycogen
 How do plants store
glucose?
 Starch
 What are the polymers
of carbohydrates
 polysaccharides
 What are the polymers
of protein?
 Polypeptides
 What are the only two
macromolecules that
contain nitrogen?
 Proteins
 Nucleic Acids
 Which macromolecule
is nonpolar?
 Lipids