Four Types of
Organic Molecules
Made by cells
Contains carbon
Importance of Carbon
Although cells are 70-95% water, the rest
are composed mainly of carbon
compounds.
Proteins, carbohydrates, DNA, and other
molecules are compounds of carbon
bonded to other elements.
Carbon often bonds to H, O, N, S, and P in
organic compounds.
Properties of Carbon
Has four valence electrons; can form
covalent bonds with four other atoms
Carbon can form single, double, or triple
bonds with other atoms.
Carbon chains form the backbone of most
organic molecules.
Chains can be straight, branched, or
arranged in closed rings.
Hydrocarbons contain carbon and
hydrogen only, and are hydrophobic. H—C
and C—C bonds are nonpolar.
Hydrocarbons make up fossil fuels, and
parts of cellular organic molecules such as
fats and phospholipids.
Organic Molecules are made by cells and
contain carbon
4 Types of Organic Molecules:
1. Carbohydrates- used as fuel and building
material
2. Lipids-energy storage
3. Proteins-structure, movement, enzymes
4. Nucleic acids-store and transmit hereditary
information.
They are macromolecules because of their
large size.
The largest
Macromolecules
are called polymers
Created by linking
smaller subunits
called monomers.
Condensation (Dehydration)
Monomers are linked together to form polymers
through dehydration reactions, which remove
water
This process is called dehydration because water is
removed
Monomers are linked together by covalent bonds
Short polymer
Dehydration
reaction
Longer polymer
Unlinked
monomer
Dehydration is the mechanism
for Anabolic pathways
Anabolic pathway – metabolic pathway
that consumes energy (in the form of ATP)
to synthesize a complex molecule for a
simpler molecule

Exs. Amino acids building to proteins,
nucleotides building to DNA,
monosaccharides building to polysaccharides
“Anabolic steroids” work to stimulate protein
synthesis and muscle growth
Hydrolysis
Polymers are broken apart by hydrolysis, the
addition of water
Hydro means water and lysis means to rupture or
break apart. You break apart molecules by adding
water.
Breaks covalent bonds between monomers
Hydrolysis
Hydrolysis is the mechanism for
catabolic pathways
Catabolic pathway – A metabolic pathway
that releases energy by breaking down
complex molecules to simpler compounds

Exs. The reverse of all anabolic reactions,
Digestion of all food would be a catabolic pathway
that releases energy for the body to use in cellular
respiraiton
Cellular respiration = making of ATP
ATP
ATP is a high energy molecule used to power
cellular work
Structure: 1) sugar robse with the nitrogenous
base adenine, 2) chain of 3 phosphates

The 3 phosphates are all negatively charges. Thus,
they repel one another and lead to very unstable
bonds. The breaking of the 3rd phosphate (to create
ADP) is an exergonic (releases free energy - G)
reaction that can then be used by the cell
ATP continued
The bond broken between the second and third phosphates
on ATP creates ADP + P.
The released phosphate can “phosphorylate” another
compound making it more unstable (and thus more likely
to undergo the desired reaction)
Exergonic reaction – net release of free energy (- G)
Because these reactions release energy, they occur
spontaneously
Endergonic reaction – one that absorbed free energy from its
surroundings (+ G)
Because these reactions stores free energy, it is not spontaneous
Energy coupling: the use of an exergonic process to drive an
endergonic one
Reactions that require energy input (have a positive free-energy
change) can occur because they are coupled by the hydrolysis of ATP
Hydrocarbons
Compounds made of
only carbon and
hydrogen.
Found in a variety
of structures.
1. Length
2. Branching
3. Double bonds
4. Rings
Isomer – same molecular
formula, different structure.
Length.
Carbon skeletons vary in length.
Branching.
Skeletons may be unbranched or branched.
Skeletons may have double bonds,
which can vary in location.
Rings.
Skeletons may be arranged in rings.
functional group determine the
properties of organic compounds
Compounds containing functional groups
are hydrophilic (water-loving)
6 Functional groups
–
–
–
–
–
–
Hydroxyl group —a hydrogen bonded to an
oxygen
Carbonyl group — a carbon linked by a
double bond to an oxygen atom
Carboxyl group —a carbon double-bonded
to both an oxygen and a hydroxyl group
Amino group —a nitrogen bonded to two
hydrogen atoms and the carbon skeleton
Phosphate group —a phosphorus atom
bonded to four oxygen atoms
Methyl group – a carbon bonded to three
hydrogens.
4 different types of Organic
Molecules
1. Carbohydrates (monomer =
monosaccharide)
Function: Most carbohydrates are used for energy, but
some of them are used for structure
 All carbs are in a 1:2:1 ratio of C:H:O
•
The common name for carbohydrates is “sugars”
•
Most carbohydrates (but not all) end in the letters “ose”.
•
Carbohydrates occur in the form of 1 (mono), 2 (di), or
more (poly) rings
There are 3 different types of carbohydrates:
1.
2.
3.
Monosaccharide
Disaccharide
Polysaccharide
3 different types of
carbohydrates
monosaccharides – simple (one) ring sugars
Chemical Formula: C6H12O6
• Monosaccharides give energy quickly because
they can be broken down easily by the body.
Even so, this energy does not last for long because it
is used up very quickly.
Types:
a. Glucose – 6 carbon sugar found in blood
b. Fructose – 6 carbon sugar found in fruit
c. Galactose – 6 carbon sugar found in peas
•
Monosaccharides
Monosaccharides
Diabetes
Disease characterized by high levels of
blood glucose resulting from defects in
insulin production
Monitored with blood glucose device.
2. Disaccharides – 2 ring sugar
• Made by joining 2 monosaccharides by process of dehydration
• These sugars give energy that lasts a little longer than
monosaccharides because the glycosidic bond (a covalent bond
between two monosaccharides) must be broken before the sugar
can be used for energy
Examples
Sucrose = table sugar (made by Glucose + fructose)
Lactose = milk sugar (made by Glucose + galactose)
Maltose = malt sugar (made by glucose + glucose)
Remember dehydration reaction!
(Makes a glycosidic linkage – O binds 2
monosaccharides)
What kind of bond would this linkage be?
Glucose
Glucose
Maltose
Lactose intolerant
If the enzyme lactase is not present, the body is unable to
break down lactose. Allowing it to reach the large intestines.
Normally, sugars do not reach the large intestine. This is what
causes a stomach ache!
3. Polysaccharides – many ringed sugar (repeating
units of monosaccharides)
Usage: energy storage and as structural components.
Examples:
Energy


starch (plants produce for a storage molecule.)
glycogen (storage molecule in muscle and liver cells.)
Structural (only 2 carbs we’ll talk about that aren’t used for
energy)

cellulose (plants produce for cell wall construction.)
indigestible because we lack enzymes to break it down.

chitin (used by insects and crustaceans to build an
exoskeleton.)
Starch, Cellulose & Glycogen
All the sugars
are oriented in
the same
direction
Branched or
"forked"
Every other
sugar molecule
is "upside-down
Monosaccharides
Cellulose
Review Q:
Polymers of carbohydrates are all
synthesized from monomers by
A) the joining of disaccharides.
B) hydrolysis.
C) dehydration synthesis.
D) ionic bonding between monomers
E) cohesion.
2. Protein Made of a long chain of amino acids
linked by dehydration reaction
Proteins, cont.
Proteins make up 50% of cellular dry
weight.
Each type has a unique 3-D shape.
Vary in structure and function, but all are
made from the same 20 amino acids.
Amino acids (monomer for
protein)
Have an amino group and a carboxyl group
Also a chemical group symbolized by R
Amino
group
Carboxyl
group
–
Dehydration reaction links the carboxyl group
of one amino acid to the amino group of the
next amino acid
– The covalent linkage resulting is called a peptide
bond
Carboxyl
group
Amino
group
Dehydration
reaction
Peptide
bond
Dipeptide
Amino acid
Amino acid
Peptide bonds
Peptide bonds are covalent bonds formed by
a condensation reaction that links the
carboxyl group of one amino acid to the
amino group of another.
Has polarity with an amino group one end (Nterminus) and a carboxyl group on the other
(C-terminus).
Has a backbone of repeating N-C-C-N-C-C
Polypeptide chains range in length from a few
monomers to more than a thousand, and a
unique linear sequence of amino acids.
The R group determines if the amino acid
is hydrophobic or hydrophilic.
Hydrophobic
Leucine (Leu)
Hydrophilic
Serine (Ser)
Aspartic acid (Asp)
A protein’s specific shape
determines its function
A polypeptide chain contains hundreds or
thousands of amino acids linked by
peptide bonds
–
–
The amino acid sequence causes the
polypeptide to assume a particular shape
The shape of a protein determines its specific
function
A.A. sequence = shape = function!
Proteins have many functions
Structural proteins (support)


keratin for hair and nails
collagen for bones, ligaments, tendons, skin
Proteins function as…
Contractile

Found in muscle cells, enables them to move.
Proteins function as…
Enzymes - proteins that promote chemical
conversions, as well as speeds up
reactions.
Example: Amylase is an enzyme in saliva
that breaks starch into glucose monomers.
Saliva
Saliva Identification - Amylase
Proteins function as…
Transport across cell membranes

Ex. Hemoglobin
Defense from infection

Antibodies
Signal

hormones
Insulin
Insulin is a hormone
that helps your body
use glucose.
Proteins function as…
Storage

Source of food for developing embryos.
Albumin (egg whites)

experiences heat coagulation (denaturation)
Protein in seeds.
Receptor

Built in cell membrane. Transmits signals to
the inside of the cell.
Proteins: Cellular function
(Review)
Structural support
Storage of amino acids
Transport, such as hemoglobin
Signaling, chemical messengers
Cellular response to chemical stimuli (receptor
proteins)
Movement (contractile proteins)
Defense (antibodies)
Catalysis of biochemical reactions (enzymes)
Groups of Amino Acids
Amino acids are put into groups based on the
side chains the molecule contains, and its
properties.
Nonpolar, hydrophobic side groups make amino
acids less soluble in water.
Polar, hydrophilic side groups make amino acids
soluble in water. These can be uncharged polar
side groups, or charged (acidic or basic) groups.
NONPOLAR AMINO ACIDS
POLAR AMINO ACIDS
Protein conformation: 3-D structure
Each protein molecule has a unique native
conformation (shape of the protein under
normal biological conditions) that reflect its
function.
Enables a protein to recognize and bind
specifically to another molecule
(enzyme/substrate, hormone/receptor,
antibody/antigen)
3-D structure, cont.
A protein’s shape is produced when a
newly formed polypeptide chain coils and
folds spontaneously, mostly in response to
hydrophobic interactions.
Is stabilized by chemical bonds and weak
forces between neighboring regions of the
folded protein.
Overview of Protein Structure
Four levels of protein structure
Primary- amino acid sequence
Secondary- regular repeated coiling and folding
of a protein’s amino acid chain
Tertiary- 3-dimensional shape of a protein due to
bonding between side chains
Quaternary- results from interactions between
several polypeptide chain (protein has subunits,
like hemoglobin and collagen)
Primary
Structure
Secondary Structure
Coiling and folding of the polypeptide backbone
Stabilized by hydrogen bonds between peptide
linkages in the amino acid chain
Two major types:
Alpha helix- helical coil stabilized by hydrogen
bonds between every 4th peptide bond. Found in
fibrous proteins such as collagen.
Beta pleated sheet- antiparallel chains fold into
accordian-like pleats, held by hydrogen bonds. Form
the dense core of globular proteins (lysozyme) and
some fibrous proteins (silk)
Secondary
Structure:
Alpha helix or
Beta-pleated sheet
Tertiary structure
3-D shape of a protein due to bonding between side
chains, and interactions with the aqueous environment.
Protein shape is stabilized by:
Weak interactions such as hydrogen bonding between
side chains, ionic bonds between charged side chains,
and hydrophobic interactions between nonpolar side
chains
Covalent linkages such as disulfide bridges between
two cysteine monomers brought together by protein
folding
Quaternary structure
Occurs in proteins made up of two or more
polypeptides, resulting from the interactions
between them.
Collagen is a fibrous protein with three helical
polypeptides supercoiled into a triple helix;
makes it very strong connective tissue in
animals
Hemoglobin is a globular protein with four
subunits that fit together.
Protein conformation
Protein’s 3-D shape is a consequence of
the interactions responsible for secondary
and tertiary structure.
Protein conformation is influenced by the
physical and chemical environment
If a protein’s environment is changed, it
may become denatured and lose its
shape.
Denature
Protein structure is key to their function
Denature – a protein loses its shape (and
consequently its function) when it is taken
out of its natural range for factors such as
temperature, pH, or salinity
Denaturation
Process that changes a protein’s structure,
therefore affecting its biological function. Can
be caused by:
1) Heat- disrupts weak interactions
2) Chemical agents that disrupt H-bonds, ionic
bonds, and disulfide bridges (pH for example)
3) Transfer to an organic solvent causes
hydrophobic chains to move toward the
outside, while the hydrophilic side chains turn
toward the interior.
Review Q:
The linkage between the monomers of
proteins are identified as
A) Peptide bonds
B) Glycosidic linkages
C) Ionic bonds
D) Covalent bonds
E) Ester linkages
Review Q:
Which two functional groups are always
found in amino acids?
A) Amine and sulfhydryl
B) Carbonyl and carboxyl
C) Carboxyl and amine
D) Alcohol and aldehyde
E) Ketone and amine
3. Nucleic Acids
Function: Hereditary material and
instructions for making proteins
Two types:
DNA
(deoxyribonucleic acid)

RNA
(ribonucleic acid)

Nucleic Acids: Informational Polymers
Nucleic acids store and transmit hereditary
information.
DNA stores information for the synthesis
of specific proteins.
RNA, specifically mRNA, carries this
genetic information to the protein
synthesizing machinery (ribosomes).
Nucleic acids, cont.
Nucleic acids are polymers of nucleotides.
Each nucleotide monomer consists of a
pentose (5-C sugar) covalently bonded to a
phosphate group and to one of four
nitrogenous bases (A,G,C, T or U).
In making a chain, nucleotides join to form a
sugar-phosphate backbone from which the
nitrogenous bases project.
The sequence of bases along a gene
specifies the amino acid sequence of a
particular protein.
Nucleotides are the building
blocks of Nucleic acids.
Have 3 parts:
* 5 carbon sugar
* phosphate group
* nitrogenous base group
4 base pairs
DNA nitrogenous bases are




adenine (A)
thymine (T)
cytosine (C)
guanine (G)
RNA also has A, C, and G, but instead of
T, it has uracil (U)
Double helix
Two DNA strands wrap around each other
to form a double helix
–
–
–
The two strands are connected by a
hydrogen bond between the base pairs.
A pairs with T
C pairs with G
RNA is usually a single strand
Genes are enough DNA to code for the
sequence of amino acids for 1 protein
(primary structure of proteins).
Genes do not use DNA to code directly.
Genes use an intermediary (RNA).
The DNA is transcribed into RNA, which is
then translated into the amino acid
sequence.
Flow of information:
DNA  RNA  Proteins
Review Q:
Which list of components characterizes
RNA?
A) A phosphate group, deoxyribose, and
uracil
B) A phosphate group, ribose, and uracil
C) A phosphate group, ribose and thymine
D) A phosphate group, deoxyribose, and
adenine
4. Lipids
Functions:
1. Energy storage- fats store twice as many calories/gram as
carbs.
2. Protection of vital organs and insulation in humans and other
mammals.
3. Phospholipids make up cell membranes.
4. Steroids are often in cell membranes (cholesterol) and make
up some hormones (estrogen and testosterone)
Monomer:
No single monomer for lipids (each type of lipid has its own
monomers)
Lipids are Hydrophobic – Will not mix with water
Types of Lipids
1. Fats
Risk factors to Saturated fats


Atherosclerosis
Heart Disease
Types of Lipids:
2. Phospholipids - form cell membranes
Hydrophilic
head
Hydrophobic
tails
The polar heads are
towards the water,
the nonpolar tails are
on the inside of the
cell.
Phospholipids
Where fats have a third fatty acid linked to
glycerol, phospholipids have a negatively
charged phosphate group.
This makes the “head” of the phospholipid
hydrophilic; the hydrocarbon “tails” are
hydrophobic.
Phospholipids are the major components of cell
membranes. In a cell membrane, the
hydrophobic tails are orientated inward, while
the hydrophilic head face outward.
 3. Steroids cell messengers
 examples: testosterone, estrogen (estradiol)
 Steroids have a basic structure of four fused rings
of carbon atoms.
 4. Waxes protection & waterproofing
Review Q:
Which macromolecule is the main
component of cell membranes?
A) Glucose
B) Steroids
C) Carbohydrates
D) Phospholipids
E) DNA
Review Q:
Which of the following macromolecules below
could be structural parts of the cell, enzymes,
or involved in cell movement or
communication?
A) Nucleic acids
B) Proteins
C) Lipids
D) Carbohydrates
E) Minerals