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2.3 Carbon-Based Molecules
KEY CONCEPT
Carbon-based molecules are the foundation of life.
2.3 Carbon-Based Molecules
Carbon atoms have unique bonding properties.
• Carbon forms covalent bonds with up to four other atoms,
including other carbon atoms.
• Carbon-based molecules have three general types of
structures.
– straight chain
– branched chain
– ring
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The Importance of the Carbon Backbone
• The carbon backbone allows large molecules to form,
which make up life!
– Organisms use these molecules to build their bodies.
– Carbon atoms can bind to each other or to other
atoms in an endless variety of shapes.
– The different shapes that carbon can create are the
molecules necessary for life
- Shape determines function!
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Macromolecules
• Carbohydrates, lipids, proteins, and
nucleic acids are referred to as
macromolecules because of their large
size.
– Also called polymers
- They are made up of monomers.
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• Macromolecules are made of many small
subunits bonded together.
– Monomers are the individual subunits.
– Polymers are made of many monomers.
How are
polymers
formed??
13.1 Ecologists Study Relationships
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Four main types of carbon-based molecules are found in
living things.
• Carbohydrates are made of carbon,
hydrogen, and oxygen.
Simple carbs =
sweet- tasting
sugars
Complex carbs =
starch, cellulose,
chitin
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Four main types of carbon-based molecules are found in
living things.
• Carbohydrates’ function is to provide a quick source of
energy for living things
Classification:
A. Monosaccharides
– simple sugars
– glucose, fructose,
galactose, ribose,
deoxyribose
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B. Disaccharides
- Two monosaccharides chemically bonded together by
dehydration synthesis
- Maltose, sucrose, lactose.
C. Polysaccharides
- Complex carbohydrates
- polymers of monosaccharides formed by dehydration
synthesis
- starch, glycogen, cellulose, chitin
13.1 Ecologists Study Relationships
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• Carbohydrates can be broken down to provide
energy for cells.
• Some carbohydrates are part of cell structure.
Polymer (starch)
Starch is a polymer of
glucose monomers that
often has a branched
structure.
Polymer (cellulose)
monomer
Cellulose is a polymer
of glucose monomers
that has a straight, rigid
structure
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Plants and animals each have different carbohydrates
used for energy storage and structure
Carb. used to store
energy:
Carb. used for
structure:
Found in
Plants:
Starch
Cellulose
Found in
Animals:
Glycogen
Chitin
(insects and
crustaceans)
13.1 Ecologists Study Relationships
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• Why is cellulose nondigestible in humans?
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Lipids
• Lipids are nonpolar molecules that include
fats, oils, and cholesterol.
• Insoluble in water due to hydrocarbon chains.
Classification:
• Fats and Oils (Triglycerides)
– Contain glycerol and fatty acids
- Glycerol- Contains three OH- groups.
- Fatty acid- consists of long hydrocarbon chain.
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– Fats and oils contain fatty acids bonded to glycerol.
Triglyceride
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• Fats and oils contain different types of fatty
acids.
– saturated fatty acids
– unsaturated fatty acids
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Types of Fats and Fatty Acids
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Coronary Arteries and Plaque
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• Phospholipids
– Polar phosphate “head” (hydrophilic)
– Nonpolar fatty acid “tails” (hydrophobic)
Phospholipid
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Phospholipids
Cell membranes
are made of
phospholipids
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Lipids
• Steroids
– Have skeletons of four fused carbon rings.
- Cholesterol, testosterone, estrogen
• Waxes
– Long-chain fatty acid bonds with a long-chain
alcohol.
-
High melting point
Waterproof
Resistant to degradation
Made by insects
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• Lipids have several different functions.
– Long-term energy storage
– broken down as a source of energy
– make up cell membranes
– used to make hormones
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Proteins
• Functions
– Support
– Enzymes
– Transport
– Defense
– Hormones
– Motion
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• Proteins
– are polymers of amino acid monomers.
– Twenty different amino acids are used to build proteins
in organisms.
One
amino
acid
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• Proteins are polymers of amino acid monomers.
– Twenty different amino acids are used to build proteins
in organisms.
– Amino acids differ in side groups, or R groups.
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• Proteins are polymers of amino acid monomers.
– Amino acids are linked by peptide bonds.
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Proteins
• Protein Structure
– Primary - Sequence of amino acids.
– Secondary - Polypeptide coils or folds in a particular
fashion.
– Tertiary - Folding and twisting that results in final
three-dimensional shape of a polypeptide.
– Quaternary - Consists of more than one polypeptide.
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• Proteins differ in the number and order of amino acids.
– Amino acids interact to give a protein its shape.
Hemoglobin
hydrogen bond
– Incorrect amino acids change a protein’s structure
and function.
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DEOXYRIBONUCLEIC
ACID
RIBONUCLEIC ACID
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• Nucleic acids are polymers of monomers called
nucleotides.
– Nucleotides are made of a sugar, phosphate
group, and a nitrogen base.
A phosphate group
nitrogen-containing molecule,
called a base
A
G
C
or
deoxyribose (sugar)
T
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• Nucleic acids are polymers of monomers called
nucleotides.
– Nucleotides are made of a sugar, phosphate
group, and a nitrogen base.
– DNA stores genetic DNA
information.
– RNA builds proteins. RNA
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DNA
Complementary base-pairing
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ATP: Adenosine triphosphate
•A special nucleotide that
contains A LOT of chemical
energy
•Energy is stored in the
phosphate bonds
•It is the “energy currency” for all
living things