Modeling Lab – Simple Biological Molecules
Background Information – read carefully
In biology the four (4) most important elements found in living things
are:
C – carbon which can make up to 4 bonds with other atoms
H – hydrogen which can make one bond with another atom
O – oxygen which can make up to 2 bonds with other atoms
N – nitrogen which can make up to 3 bonds with other atoms
P – phosphorus which can make up to 3 bonds with other atoms
S – sulfur which can make up to 2 bonds with other atoms
Of these six (6) elements, carbon is the dominant player because it
can:
 bond with up to 4 other elements,
 bond to other carbons to make chains, rings and branched
structures, and
 support single, double or triple bonds.
Carbon in found in almost every molecule in living things. These
carbon rich molecules come in a variety of shapes and these shapes
with their “hot spots” i.e. functional groups, are what enable life
processes (chemical reactions) and life’s structures to exist. So shape
matters!!!
The huge molecules in living things are collections of smaller building
blocks are that coupled together in very specific ways to create very
specific shapes. It is the specific shape and the functional groups in
the molecules that make life possible.
Today you will use molecular modeling kits to build a variety of these
simpler molecules and important functional groups.
Lab Objectives:
 build basic structures of simple molecules.
 identify the five (5) major functional groups in biomolecules
 visualize the three dimensional structure of these molecules
and sketch them.
Part I – A Quick Review
1. Complete the table before starting
Element
Hydrogen
Oxygen
Model color
Nitrogen
Carbon
Chemical
symbol
Number of
single
bonds
possible
2. Draw the structural formulas for each of the following simple
compounds:
Molecule
Formula Shape
Check
Methane
CH4
Water
H2 O
Carbon dioxide
CO2
Ammonia
NH3
3. Now build each of these molecules using your model kit. For
double bonds use the long, thin, flexible connectors. When you
have finished the four molecules, have your teacher initial the
table above.
Part II – Functional Groups
1. There are five major functional groups in the molecules of living
things.
a. hydroxyl group – a hydrogen and an oxygen atom are
connected by a single covalent bond
b. carbonyl group – a carbon atom double bonded to an
oxygen atom
c. carboxyl group – a carbon atom double bonded to an
oxygen atom and to a hydroxyl group
d. amino group – a nitrogen atom attached to tweo hydrogen
atoms by single covalent bonds
e. phosphate group - a phosphorus atom double bonded to
one oxygen atom and singly bonded to three other oxygen
atoms
2. Build the structural models for each of the following functional
groups and then make a sketch in the last column:
Functional Group
Formula
Shape
(Notes)
Check
Hydroxyl group
-OH
Carbonyl group
C=O
Carboxyl group
-COOH
Amino group
-NH2
Phosphate group
-PO4
Part III – Building Simple Biomolecules
Name
Carbon
Dioxide
CO2
1. Using your molecular model kit, build each of the simple
molecules in the table below.
Formula
Description
shape
Functional
groups
present
O=C=O
One of the main
products of cellular
respiration and one
of the main
reactants of
photosynthesis
Water
H2O
O
/ \
H H
One of the main
products of cellular
respiration and one
of the main
reactants of
photosynthesis
Ammonia
NH3
N
/ | \
H H H
Main source of
nitrogen for living
things. Bacteria
capture nitrogen
from the air
through a chemical
reaction that
produces ammonia
Phosphoric
Acid
H3PO4
Ethanol
C2H6O
O
||
H-O-P-O-H
|
O-H
H H
 
H—C—C—O—H
 
H H
Impacts bone
density; found in
sodas
yeasts carry out
ethanol
fermentation ,
breaking down
sugar in the
absence of oxygen
to make ethanol.
this reaction causes
bread dough to rise
and beer to ferment
Check
Acetic Acid
C2H5O2
H O
 
H—C—C—O—H
 
H H
The sourness of
vinegar comes from
the acetic acid it
contains
Urea
CN2H4O
O

H—N—C—N—H


H
H
When proteins are
digested and burned
for energy,
ammonia (toxic) is
created. Ammonia
is converted to less
toxic urea in the
liver
Questions (to be answered after completing the lab.)

What types of functional groups are found in ethanol, acetic acid?

How are acetic acid and ethanol alike? Different?

What are the functional groups in urea?