Carbon-Based Molecules Part 1
Biochemistry
Objectives
• SWBAT describe the bonding properties of
carbon atoms.
• SWBAT compare carbohydrates, lipids,
proteins, and nucleic acids.
Starter
• We have talked about carbon based molecules
in other units. I want you to take a couple of
minutes and make a list of the carbon based
compounds we have touched on in this class
or you have heard about in other places.
– You may work in groups.
Vocabulary for Unit 2.3 (P. 44)
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Monomer
Polymer
Carbohydrate
Monosaccharide
Polysaccharide
Starch
Cellulose
glycogen
Lipid
Fatty acid
Protein
Amino acid
Nucleic acid
Carbon: Building Blocks of Life
• Carbon atoms are the basis of most molecules
making up living things.
– They form the structure of living things.
– Carry out most of the processes that keep
organisms alive.
– Carbon atoms have special bonding properties,
due to its atomic structure, which are unique
among elements.
Carbon: Building Blocks of Life
– Carbon atom has four unpaired electrons in its
outer energy level – allowing it to form covalent
bonds with up to four other atoms (including
other carbon atoms).
Carbon: Building Blocks of Life
• Because Carbon can form four other covalent
bonds, it can form large molecules (long
chains and rings).
Hydrocarbons are classified based on
how many carbons strung together
How Cleanly a hydrocarbon burns is based on the length of the
carbon chain. Fewer carbons equals cleaner burning.
Quick Question
• Why is methane considered clean burning?
• When it burns, what does it produce?
Carbon Chains and Rings
• Carbon-based molecules have 3 fundamental
structures (creating a lot of flexibility):
1. Straight chains (Pentene)
2. Branched chains (Iso-butane)
Carbon Chains and Rings
– Rings (Vanillin and Hexane ring)
• To reiterate, the bonding flexibility is due to
the carbon’s ability to enter into up to 4
covalent bonds at the same time – forming
large molecules
Links in a chain
• Large carbon molecules are made out of many smaller ones
linked together.
Links are called monomers, the chains are
polymers.
• Each link, a smaller molecule, is known as a
monomer (mono means one).
• Monomers linked together form a polymer (a
molecule that contains many monomers bonded
together.
Links are called monomers, the chains are
polymers.
Question to check understanding
• What is the difference between a monomer
and a polymer?
Carbohydrates
• The word carbohydrate literally means
“watered carbon.”
• Do you remember the chemical formula for
glucose? How does that remind us of the
formula for water?
• C6H12O6
Carbohydrate Definition
• Molecules composed of carbon, hydrogen, and
oxygen.
– They include sugars and starches.
• Carbohydrates can be broken down to provide a
source of usable chemical energy for cells.
• They are a major part of plant cell structure (our
producers).
Glucose – simple sugar
• The most basic carbohydrates are simple
sugars.
– Glucose is a simple sugar (it contains six carbons
and is called a monosaccharide).
– Fructose, found in fruit, is another six carbon
monosaccharide.
Simple sugars can be bonded together
• Quick Test: When is glucose made?
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Answer - photosynthesis
• Simple sugars can be bonded to one another
to make larger carbohydrates called
polysaccharides.
This is glucose
linked as
polysaccharides.
Connecting a concept
• Glucose is a monosaccharide – this makes it a
what?
• Answer – a monomer
• A chain of glucose is a polysaccharide – so, a
chain of glucose monomers makes a . . .
• Polymer – a polymer is known as a
macromolecule.
So . . .
• Multiple monosaccharides (monomers) linked
together form polysaccharides (polymers).
• Examples:
Starch (storage
This is a disaccharide
known as table sugar
and source of
energy in plants),
glycogen (storage
and energy
source in animals,
and cellulose
(plant structure),
are
polysaccharides
Cellulose, Starch, and Glycogen
• Cellulose is a rigid, straight polymer which makes
up the cell walls of plants.
– it is tough and fibrous (a good source of your fiber).
• Starch – made and stored by plants and can be
broken down for energy by both plants and
animals.
• Glycogen – made and stored in animals is highly
branched but essentially does the same thing in
animals that starch does in plants.
Interesting Fact
• Few animals have enzymes that allow them to
hydrolyze cellulose.
• Primary consumers (cows, pigs, goats, deer,
termites, etc.), however, are able to use
cellulose for nutrients because of protists and
bacteria living in their guts.
• Cellulose is the most abundant organic
molecule on Earth.