Chapter 5: Molecules of Life
VOCABULARY
Organic Molecules – Molecules that contain 2 or more carbon atoms.
Example: C6H12O6 – glucose, fructose, galactose
C5H10O5 – deoxyribose, ribose
Inorganic Molecules – DO NOT contain carbon (ex: water, H2SO4,
contain only ONE carbon atom (ex: CO, CO2)
HCl, NaCl) OR
Monomers – Small organic molecules that bond together to form large, complex molecules
called polymers.
Polymers – large, complex organic molecules; Ex: carbohydrates, lipids, proteins, nucleic acids
Dehydration / Condensation Reactions – chemical reaction in which 2 molecules are bonded together and a
molecule of water is removed.
Hydrolysis Reactions – chemical reactions which break large molecules/polymers back down into their
original monomers by adding water to the molecule.
DID YOU KNOW THAT:



73% of your body is made of water; 26% of your body is made of organic molecules; 1% of your
body is made of minerals.
Our body uses water during digestion to break down the plant and animal polymers that we ingest into
monomers; hydrolysis reactions. The monomers are used by our cells to build new human polymers;
dehydration reactions.
SIX IMPORTANT BIOLOGICAL ELEMENTS ARE: C, H, N, O, P, S
CARBON, HYDROGEN & OXYGEN are 3 elements that form ALL organic molecules.

4 Groups of Organic Molecules Required by Cells

1. Carbohydrates (aka: carbs) – provide cells with energy; Ex: sugars, starch, cellulose,
glycogen and chitin.
2. Lipids- store energy for cells; form cell membranes; Ex: fats, oils, waxes, phospholipids,
steroids.
3. Proteins – building material: forms cell membranes, forms chromosomes, allow chemical
reactions to occur; Ex: hemoglobin, collagen, actin & myosin, enzymes
4. Nucleic Acids – involved in heredity (form our chromosomes), help make proteins (protein
synthesis); Ex: DNA and RNA
Carbohydrates
Function: Provide cells with energy.
Composed of the following elements: carbon, hydrogen, oxygen (C, H, O) in a 1:2:1
ratio.
Monomers: monosaccharides (simple sugars)
Note: Carbohydrates USUALLY end in the suffix -OSE.
Types of Carbohydrates:
1. Monosaccharides: simple sugars; usually contain 3 – 6 carbon atoms.
Examples:

Pentose sugars – contain 5 carbons
Ribose, deoxyribose, ribulose – C5H10O5

Hexose sugars – contain 6 carbons
Glucose, fructose, galactose - C6H12O6
2. Disaccharides: complex sugars formed by bonding 2 monosaccharides
together and removing a molecule of water (dehydration
reaction).
C6H12O6 +
C6H12O6

C12H22O11 + H2O
Examples:

Glucose + Fructose 

Glucose + Glucose
Sucrose
+
(table sugar)

Maltose
+
H2O
H2O
(grain sugar)

Glucose + Galactose 
Lactose
+
H2O
(milk sugar)
3. Polysaccharides: complex carbohydrates made by joining many glucose
monomers together via dehydration reactions.
a. Storage Polysaccharides – energy storing molecules
 Starch – formed by plants from excess glucose; stores energy
for winter.

Glycogen – formed by humans/animals & stored in our liver
and muscle cells; provides our cells with energy when we skip
meals.
b. Structural Polysaccharides – building molecules
 Cellulose – formed by plants to build cell walls.
 Chitin – formed by insects to build their exoskeleton.
Lipids
Functions: Store energy, build cell membranes, insulation, form hormones.
Composed of the following elements: carbon, hydrogen, oxygen (C, H, O)
Monomers:
Glycerol + 3 Fatty Acid molecules
Formation of a Lipid/Fat Molecule
Glycerol + 3 Fatty Acids 
Fat/Lipid Molecule + 3H2O
Types of Lipids:
1. Fats – butter, lard, animal grease/drippings
 Mainly produced by animals
 Usually solid at room temperature
 Made of glycerol + 3 saturated fatty acids
 Too much in diet may lead to clogged arteries (aka:arteriosclerosis)
2. Oils – corn, olive, sunflower, peanut, and vegetable oil
 Mainly produced by plants
 Usually liquid at room temperature
 Made of glycerol + 3 unsaturated fatty acids
 Better for you than fats, but in moderation
3. Waxes – Examples:
 On the skin of fruits; i.e.: apples
 On surface of leaves to prevent water loss
 Ear wax protects ear canal
 Bees wax forms the honeycomb
4. Steroids – Ex: Cholesterol
 Part of animal cell membranes
 Forms female sex hormone estrogen
 Forms male sex hormone testosterone
Proteins
Functions: Build cell membranes, form our chromosomes, act as enzymes which
cause chemical reactions to occur in cells
Composed of the following elements: C, H, O,
N
Monomers: 20 Amino Acids (Can be combined in an infinite number of
combinations to make an infinite number of proteins; just like the 26
letters of our alphabet)
Types of Proteins:
1. Actin and Myosin – proteins that cause our muscles to contract & relax
2. Hemoglobin – in our red blood cells/erythrocytes; transports oxygen to
cells, tissues, organs
3. Antibodies – produced by our immune system; fight infection
4. Collagen – helps form skin, bone, tendons, and ligaments
Nucleic Acids
Functions: DNA forms our chromosomes & gives us our hereditary traits;
RNA helps cells make proteins & forms ribosomes
Composed of the following elements: C, H, O, N,
P
Monomers: Nucleotides (made of 5-carbon sugar, phosphate group, nitrogen base)
Types of Nucleic Acids:
1. DNA – deoxyribonucleic acid
 Forms chromosomes (along with protein)
 Carries heredity information (aka: genes)
2. RNA – ribonucleic acid
 Involved in making proteins during protein synthesis
CARBOHYDRATES
Elements They
Contain
_____________________
Ratio:
LIPIDS
___________________
Ratio: 1:2 of carbon to hydrogen, with very
little oxygen.
________________ + ________________  fat +3H2O
Monomers
(building blocks)
Functions in
Cells/Body
Types of:
(and function)
1._______________________ simple/single sugars containing 3-6
carbon atoms.
1. _________ - these lipids are solid at room
temperature & are formed by animals.
Examples:

Examples:
Name 2 pentose sugars:
a.___________________
_______________________________________

Saturated Fats – mainly animal fats.
Should be consumed in limited
amounts, as they can lead to heart
disease/clogged arteries.
b. __________________
c. Chemical formula for a pentose
sugar _______________
d. Penta means ___________

2. __________ - these lipids are liquid at
room temperature & are formed by plants.
Examples:
Name 3 hexose sugars:
a. __________________
b. __________________
_______________________________________

Unsaturated Fats – mainly plant oils.
Better to eat than saturated fats, but
also in limited amounts.
c. __________________
d. Chemical formula for a hexose
sugar
_______________

Hydrogenated Fats – are made by
adding hydrogen atoms to oils/
unsaturated fats, which makes them
solid at room temperature. Should
also be consumed in moderation.
e. Hexa means ___________
NOTE:
One gram of lipid contains
twice as much energy as the same amount
of carbohydrate or protein.
Types of:
(Carbohydrates – continued)
(Lipids – continued)
2. _____________________complex sugars containing 12 carbon
atoms.
Identify some foods that contain lipids.
(and function)

Examples:
Name 3 disaccharides
a. glucose + glucose  _________________ + H2O
1.
2.
3.
b. glucose + fructose  _________________ +
H2O
c. glucose + galactose  ________________ + H2O
3. _____________________________ complex carbohydrates formed from
hundreds of glucose monomers.

Examples:
Storage Polysaccharides:
a. _________________ - produced
by plants from excess glucose;
will be used for energy in
winter.
b. _________________ - produced by
animals from excess glucose; stored
in liver & muscle cells.

Structural Polysaccharides:
a. _________________ - produced
by plants from excess glucose;
used to build cell walls.
b. ______________ - produced by
insects from excess glucose; used
to form exoskeletons of insects.
Miscellaneous
Define the following terms:
mono - ___________
poly - __________
di - ___________
saccharide - ______________
Identify at least 3 foods that contain complex
carbohydrates.
_____________, _____________, ____________
NOTE:
One gram of lipids contains
twice as much energy as the same amount
of carbohydrate or protein.
PROTEINS
NUCLEIC ACIDS
Elements They
Contain
Monomers
(building blocks)
1.
1.
Functions in
Cells/Body
2.
2.
3.
1.
1.
Types of:
(and function)
2.
2.
3.
4.

Miscellaneous
All living things use the same 20
amino acids to build their
proteins. There is no limit to the
number of different protein
molecules that can be made.
(Just like using the letters in our
alphabet to form new words –
the possibilities are endless.)

All living things use the same 4
nucleotides to build their DNA &
RNA. There is not limit to the way
these nucleotides can be arranged to
form different types of DNA & RNA.
That’s why no 2 organisms look
exactly alike, unless they are identical
twins, triplets, etc.

Nucleic acids DNA & RNA are found
in the nucleus of all cells.