SBI4U: Biochemistry
Molecular Shape and
Function
Functional Groups Activity
In organic chemistry, functional groups are specific groups of atoms within molecules that determine their characteristics and chemical reactivity. Functional groups are attached to the carbon backbone of organic molecules. We are going to identify some key functional groups that occur in biologically important molecules.
Using your molecule model kit, build each of the functional groups listed below. Use the appropriate connectors specified by your teacher to distinguish between single and double bonds.
a. Hydroxyl group - Functional group consisting of an oxygen atom and a hydrogen atom connected by a covalent bond.
–OH
b. Carbonyl Group - Functional Group composed of a carbon atom double bonded to an oxygen atom. If this functional group occurs at the end of a molecule, it is called an aldehyde. If this functional group occurs in the middle of two carbons in a molecule, it is called a ketone.
>C=O (ketone) –COH (aldehyde)
c. Carboxyl Group – Functional Group composed of one carbon atom attached to an oxygen atom by double bond and to a hydroxyl group by a single bond. This functional group donates a proton (H+ ion) in solution, which increases the [H+ ion] and reduces the pH.
–COOH (It doesn’t look like this. Read the description for clues.)
d. Amino Group - Functional Group composed of one atom of nitrogen attached by covalent bonds two atoms of hydrogen, leaving a lone valence electron on the nitrogen, which is available for bonding to another atom. This functional accepts protons (H+ ions) in solution, which decreases the[H+ ion] and increases the pH.
–NH
2
e. Phosphate Group - Functional Group composed of one central phosphorus atom surrounded by four oxygen atoms. This functional group is actually a polyatomic ion, called a phosphate ion.
Phosphates are most commonly found in the form of adenosine phosphates (the energy all living things use) and in DNA and RNA.
What is the phosphate ions charge?
___________________
e. Sulfhydryl Group - Sulfur is found in certain amino acids and proteins in the form of sulfhydryl groups. These groups play an important role in maintaining the 3-D structure of proteins in the body.
Since we do not have a model piece for sulfur in the kit we will not build this functional group.

SBI4U: Biochemistry
Molecular Shape and
Function
–SH
Functional Groups Activity
Organic molecules are molecules that contain the atom carbon. Since carbon has 4 valence electrons, it is the most important molecule because it can bond with up to 4 other elements, it can bond to other carbons to make chains, branches, and rings, and it can have single, double, or triple bonds!
Using your molecule model kit, build each of the simple organic molecules listed below. Use the appropriate connectors specified by your teacher to distinguish between single and double bonds.
1.
Ethanol (C
2
H
6
O; ethyl alcohol). Yeasts carry out ethanol fermentation, breaking down sugars in the absence of oxygen. Ethanol fermentation is responsible for the rising of bread dough, the production of ethanol in alcoholic beverages, and for much of the production of ethanol for use as fuel. a) What type(s) of function group(s) are in this molecule?
____________________________________________________________ b) Is this a polar or a non-polar molecule? Explain.
____________________________________________________________ c) What organism carries out ethanol fermentation?
____________________________________________________________ d) What are two products produced in the ethanol fermentation reactions?
____________________________________________________________
2.
Acetic acid: The sourness of vinegar is due to acetic acid. a) What type(s) of functional group(s) are in this molecule?
______________________________________________________ b) Explain why vinegar tastes acidic.
______________________________________________________ c) Why is one of the carbons is only linked to three other atoms?
______________________________________________________ d) Is this a polar or a non-polar molecule in solution? Explain.
____________________________________________________________
3.
Urea (CH
4
N
2
O). When proteins are digested and burned for energy, the very toxic compound ammonia (NH
3
) is made. Ammonia is converted into urea by the liver. The slightly less poisonous urea is transported into the blood for eventual removal from the body. Urea is composed of a

SBI4U: Biochemistry
Molecular Shape and
Function
Functional Groups Activity central carbon double bound to an oxygen with two amino groups attached. Construct it. a) What type(s) of functional group(s) are in this molecule?
______________________________________________________ b) What does your body do to ammonia? Why?
______________________________________________________
4.
Amino Acids – the building blocks of proteins. There are twenty that commonly occur in nature.
Build the following amino acids: i. Alanine a) What type(s) of functional group(s) are in this molecule? ii. Serine a) What type(s) of functional group(s) are in this molecule?
__________________________________________________________ b) What are two things all amino acids have in common?
____________________________________________________________ c) Are amino acids polar or non-polar molecules? Explain.
____________________________________________________________
5.
Lipids - Lipids or fats are easy to make because they all long chains of carbon and hydrogen. They come in two varieties: saturated and unsaturated. Construct the following two pieces of a fat molecule. i. Saturated Fat ii. Unsaturated Fat a) What type(s) of functional group(s) are in these molecules?
___________________________________________________________________________________ b) How do saturated and unsaturated fats differ?

SBI4U: Biochemistry
Molecular Shape and
Function
Functional Groups Activity
___________________________________________________________________________________
___________________________________________________________________________________
___________________________________________________________________________________
6.
Carbohydrates – Saccharides (sugars) are organic compounds that comprise sugars, starches, and cellulose. They are important sources of energy in living things, supporting tissue in plants and probably the precursors of the fats and proteins. Most carbohydrates are built of units containing
6 carbons, although five-carbon sugars exist. i. Glucose (C
6
H
12
O
6
). The most important simple sugar (monosaccharide) used in cells. Mono means one and saccharide means sugar. Notice the main part of this molecule is a hexagon. a) What type(s) of functional group(s) are in this molecule?
______________________________________________________ ii. Fructose (C
6
H
12
O
6
). Fructose is a monosaccharide found in fruits. a) What type(s) of functional group(s) are in this molecule?
______________________________________________________ d) Are monosaccharides polar or non-polar molecules? Explain.
____________________________________________________________
Compare and contrast glucose and fructose. How are they the same/different? iii. Sucrose (C
12
H
22
O
11
). Sucrose is made up of a Glucose and Fructose molecule bonded together.
Because it is made up of two monosaccharides, it is called a disaccharide. a) Construct a sucrose molecule from your glucose and fructose models. This is a synthesis reaction that will form a basic molecule as another product.

SBI4U: Biochemistry
Molecular Shape and
Function
Functional Groups Activity b) Describe what you did to make your sucrose molecule.