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2.3 Carbon-Based Molecules
KEY CONCEPT
Organic molecules are the foundation of life.
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2.3 Carbon-Based Molecules
Objectives
• Identify what makes an organic molecule “organic”
• Identify/Recognize carbon skeletons & functional groups
in organic molecules
• Relate monomers to polymers
• Describe the processes of building and breaking
polymers (2 reactions involved)
• Describe the basic structure and function of
carbohydrates, lipids, proteins, and nucleic acids
2.3 Carbon-Based Molecules
Introduction to Organic
Biomolecules!!!!
Directions: While you watch this video, please answer the
questions on the worksheet.
• Biological Molecules - You Are What You Eat: Crash
Course Biology #3 - YouTube
2.3 Carbon-Based Molecules
Organic Molecules
• Organic Molecules
– Carbon-based molecules
– Carbon forms covalent bonds with up to four other
atoms, including other carbon atoms as it tries to fill its
outermost energy level.
• Hydrocarbons
– Organic molecules made of only carbons and
hydrogens (example CH4)
• Inorganic Molecules
– Non-carbon based molecules
– Examples: H20, NH3, O2
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2.3 Carbon-Based Molecules
Carbon atoms have unique bonding properties.
• Carbon-based molecules have three general types of
structures.
1. straight chain
2. branched chain
3. ring
2.3 Carbon-Based Molecules
Functional Groups on Organic molecules
Functional Group – group of atoms within a molecule that
interact in predicable ways with other molecules.
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2.3 Carbon-Based Molecules
Polymers vs Monomers
• Many carbon-based molecules are made of many small
subunits/peices bonded together.
– Monomers are the individual subunits/pieces
– Polymers are made of many monomers.
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2.3 Carbon-Based Molecules
Monomers bond together to build Polymers
• Each time a monomer is added to a chain a water
molecule is released (dehydration reaction)
• Each time a monomer is broken from a chain a water
molecule is added (hydrolysis reaction)
Dehydration Rxn
Hydrolysis Rxn
2.3 Carbon-Based Molecules
Dehydration Reaction (Lose Water) when adding
monomers to the polymer
2.3 Carbon-Based Molecules
Hydrolysis Reaction (add water) when breaking
polymers
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2.3 Carbon-Based Molecules
Four main types of organic molecules are found in living
things
1. Carbohydrates (5.2)
2. Lipids (5.3)
3. Proteins (5.4 & 5.5)
4. Nucleic Acids
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2.3 Carbon-Based Molecules
Carbohydrates
• Carbohydrates are made of carbon, hydrogen, and
oxygen (Ratio= 1C:2H:1O)
• Are made up of monomers of simple sugar molecules
• The building blocks (simple sugar monomers) of
carbohydrates are ring-shaped.
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2.3 Carbon-Based Molecules
Three Types of Carbohydrates
Monosaccharide
Disaccharide
Polysaccharides
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2.3 Carbon-Based Molecules
– Carbohydrates include
1. Sugars
2. starches.
– Monosaccharides are simple
sugars. (ex: glucose)
– Disaccharides are made up of two
monosaccharides (ex: sucrose)
– Polysaccharides include starches,
cellulose, and glycogen. (ex: found
in pasta & potatoes)
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2.3 Carbon-Based Molecules
Functions of Carbohydrates:
1. Carbohydrates can be broken down to provide
energy for cells ( this requires water: Hydrolysis Rxn)
2. Some carbohydrates are part of cell structure
(provide support)
Starch is a
Polymer (starch)
Polymer (cellulose)
monomer
polymer of
glucose
monomers that
often has a
branched
structure.
Cellulose is a
polymer of
glucose
monomers that
has a straight,
rigid structure
2.3 Carbon-Based Molecules
Warm-Up
1. What are the monomers of Carbohydrates?
2. List the 3 different types of carbohydrates and give an
example of each.
3. Which carbohydrate is found in plant cells?
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2.3 Carbon-Based Molecules
Lipids are nonpolar molecules that include fats, oils, and
cholesterol.
– Lipids are Hydrophobic molecules “water fearing”
– Example (oil and water don’t mix)
– Many contain carbon chains called fatty acids.
– Fats and oils contain:
– fatty acids bonded to glycerol.
2.3 Carbon-Based Molecules
Lipids
Structure Close-Up:
- Glycerol
- fatty acid chains
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2.3 Carbon-Based Molecules
• Fats and oils have different types of fatty acids.
– saturated fatty acids (bad for you)
– unsaturated fatty acids
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2.3 Carbon-Based Molecules
• Lipids have several different functions.
– broken down as a source of energy
– make up cell membranes (phospholipids)
– used to make hormones
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2.3 Carbon-Based Molecules
• Phospholipids make up all cell membranes.
– Polar phosphate “head”
– Nonpolar fatty acid “tails”
Phospholipid
Hydrophillic
Hydrophobic
2.3 Carbon-Based Molecules
A closer look at phospholipid orientation in cell
membranes:
2.3 Carbon-Based Molecules
Steroids
• Steroids are lipid molecules that form 4-Ring structures
• Function: Act as chemical signals in our bodies
– Example: Testosterone & Estrogen sex hormones
– Example: Cholesterol (in cell membranes)
2.3 Carbon-Based Molecules
Warm - Up
Lipids are hydrophobic and nonpolar. What do
those words mean?
Hydrophobic = fear of water
Nonpolar = no charged areas
• What is the name of the lipids that make up cell
membranes?
phospholipids
• What is the general structure of steroids?
4 connected Closed-Rings
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2.3 Carbon-Based Molecules
• Proteins are polymers of amino acid monomers.
– Twenty different amino acids are used to build proteins
in organisms.
Parts of an amino acid:
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2.3 Carbon-Based Molecules
• 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.
2.3 Carbon-Based Molecules
Building a Protein Polymer
• How would you put these amino acid monomers together
to form a protein polymer?
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2.3 Carbon-Based Molecules
• 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.
– Amino acids are linked by peptide bonds.
2.3 Carbon-Based Molecules
Polypeptides
• Polypeptides are the result of joining many amino acid
monomers
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2.3 Carbon-Based Molecules
• Proteins differ in the number and order of amino acids.
– Amino acids interact to give a protein its shape.
Hemoglo
bin
hydrogen bond
– Incorrect amino acids change a protein’s structure
and function.
– Denaturation – proteins loose their shape in
unfavorable conditions (temperature or pH)
2.3 Carbon-Based Molecules
Warm-Up: Organic Molecules Review
• List the 4 types of organic molecules
• Monomers of carbohydrates?
• Two main functions of carbohydrates?
• Examples of Carbohydrates?
• Lipid that makes up cell membranes?
• Two types of Fatty Acids in lipids?
2.3 Carbon-Based Molecules
Warm-Up
• What are the building blocks of Proteins?
• What are the 4 main parts of an amino acid?
• What part of an amino acid give it it’s identity?
• What reaction puts amino acids together? What happens
during that reaction?
• What special type of bond links amino acids?
2.3 Carbon-Based Molecules
Enzymes
• Many chemical reactions occur inside cells
Reactants  products
• Enzymes are protein catalysts that speed up reactions
by lowering the activation energy needed to start a
reaction.
• Activation Energy -The energy needed to start up a
reaction
• Catalyst – any compound that speeds up a reaction by
lowering the activation energy
2.3 Carbon-Based Molecules
Enzymes are never ‘used up’
• Enzymes are reaction specific
• Substrate – reactant
• Active site – groove area where substrates attach to
enzyme
• Enzymes always pick up another substrate when the
active site is unoccupied!!
• Enzyme
Animation YouTube
2.3 Carbon-Based Molecules
Enzymes Speed Up Chemical Reactions
• They are able to do this by LOWERING the activation
energy of a reaction.
2.3 Carbon-Based Molecules
A reaction utilizing an enzyme = catalytic reaction
Activation Energy is
lowered!
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2.3 Carbon-Based Molecules
• Nucleic acids are polymers of monomers called
nucleotides.
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2.3 Carbon-Based Molecules
• Nucleic acids are polymers of monomers called
nucleotides.
– Nucleotides are made of a:
- sugar
- phosphate group
- nitrogen base
A phosphate group
deoxyribose (sugar)
nitrogen-containing molecule,
called a base
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2.3 Carbon-Based Molecules
• Nucleic acids are polymers of monomers called
nucleotides.
– Nucleotides are made of a sugar, phosphate
group, and a nitrogen base.
– DNA stores genetic
information.
DNA
RNA
– RNA builds proteins.