Name:
Carbohydrate Models
Part A: WATER
1.
Name the two ELEMENTS that make up water : _________________________ and
_______________________________
2. How many HYDROGEN atoms are in a water molecule? _______________
3. How many OXYGEN atoms are in a molecule of water? _______________
4. Draw the STRUCTURAL formula for water
5. What do the lines between the O and H in the structural formula of water represent?
___________________________
Part B: CARBOHYDRATES
Carbohydrates make up a large group of chemical compounds found in cells. Carbohydrates are
produced mostly by plants for the purpose of making cell parts and as an ENERGY source. Animals
are dependent on the carbohydrate produced by plants as an energy source.
Carbohydrates contain three different elements: CARBON, HYDROGEN, and OXYGEN.
There are three basic types of carbohydrates: MONOSACCHARIDES, DISACCHARIDES, &
POLYSACCHARIDES.
Group 1: MONOSACCHARIDES
Three examples of monosaccharides are glucose, galactose, and fructose.
Find the structural formulas for these three simple sugars on page 55 of your textbook, then answer
the following questions.
1. What three elements are present in glucose, fructose, and galactose? _________________________,
___________________________, __________________________
2. How many atoms of CARBON are present in a molecule of
Glucose:___________
Fructose: __________
Galactose: _________
3. Use the diagrams in the book to find the molecular formula for each molecule. Fill in the
formula for each sugar below.
Glucose C H O
Fructose C H O
Galactose C H O
4. How many times larger is the number of hydrogen atoms than oxygen atoms in all of the
sugar molecules above? _______________________________
5. How many times larger is the number of hydrogen atoms than oxygen atoms in a molecule
of water? __________________________________
6. Why are the sugar molecules above called “carbo” “hydrates”?
7. Compare the STRUCTURAL formulas for glucose, fructose, and galactose. Are all three the
same in shape? ____________________________________________________
Group 2: DISACCHARIDES (Double sugar molecules)
Two monosaccharide sugar molecules can join together by a process called “dehydration
synthesis.” The resulting molecule is called a disaccharide. The prefix “di” means two. For
example, the disaccharide SUCROSE (table sugar) is produced by joining a glucose molecule to a
fructose molecule. Sugarcane plants and sugar beet plants are very good at this producing sucrose.
Cut and Paste!
1. Cut out a glucose and a fructose from the back page. CUT ALONG THE SOLID LINES ONLY!
Will the two molecules fit together like pieces of a puzzle? ___________
2. In order to join the molecules you have to remove a hydroxyl group from one sugar and a –
H from the other molecule. Cut along the dotted lines.
3. Does removing the –H & -OH ends now allow the molecules to fit easily together?
_____________
4. The –H & -OH ends that were removed can also fit together with each other to form a
molecule. This new molecule has a molecular formula of _______________________ and is called
_______________________.
5. Glue the molecule of glucose to the fructose molecule. Put the water molecule over the
bond between the two sugar molecules.
6. Write the molecular formula for sucrose by adding together the molecular formulas for
glucose & fructose and then subtract water.
7. Why do you think the process for creating a disaccharide is called a dehydration synthesis?
Make a molecule of maltose by joining two glucose molecules. Glue the water that is formed over
the bond that joins the sugars together. Be sure to label the sugars you have produced.
Group 3: POLYSACCHARIDES
Polysaccharides are formed when three or more simple sugars are joined together by dehydration
synthesis. The prefix “poly” means many. Starch, glycogen and cellulose are the three most
common polysaccharides studied in biology. They consist of long chains of glucose molecules
joined together.
Construct part of a starch molecule by joining three glucose molecules together by dehydration
synthesis. Glue the sugars together and paste the water molecules over the bonds where the sugars
are joined.
REVIEW
1. What must be removed from the glucose model molecules in order to have them fit easily
together? _________________
2. What is the smallest number of glucose molecules needed to form a polysaccharide?
____________________
3. Name the three categories of carbohydrates studied in this investigation.
____________________________________________________________________________________________
4. What are the three ELEMENTS that are present in carbohydrates?
________________________________________________________