LAB: BUILDING CARBOHYDRATES
MONOSACCHARIDES:
SINGLE SUGAR MOLECULES—Ex: glucose, fructose, galactose
1. Examine the structural formulas for these sugars in the diagrams below. What 3
elements are present and common to all?
2. How many carbon atoms are present in each of these?
3. How many hydrogen atoms are present in each of these?
4. How many oxygen atoms are present in each of these?
5. How many times larger is the number of hydrogen atoms than the number of
oxygen atoms in these molecules?
6. How many times larger is the number of hydrogen atoms than the number of
oxygen atoms in the formula for water?
7. Are these numbers the same?
8. Even though these 3 monosaccharides have the same number of atoms of
carbon, hydrogen, and oxygen (meaning the same chemical formula), do all of
them have the same exact structure/structural formula?
9. What common geometrical shape do they all share?
10. Define isomer.
DISACCHARIDES:
DOUBLE SUGAR MOLECULES—Ex: sucrose, maltose
1. Two monosaccharides can chemically join to form larger disaccharides. Cut out
a glucose and fructose paper model in order to form sucrose. Cut along the
SOLID lines ONLY. Attempt to join the pieces together like puzzle pieces without
removing anything. Do they fit together easily yet?
2. In order to join the 2 molecules, remove an OH from one molecules and an H
from another molecule. Now can the molecules fit together easily?
3. What basic molecule/chemical formula did you remove by removing H and OH?
This process is called DEHYDRATION SYNTHESIS.
4. Write the chemical formula for sucrose by adding together the formulas for
glucose and fructose AND then subtracting water from it. What is sucrose’s
formula?
5. Cut out and attempt to join 2 glucose paper models in order to form maltose. Cut
along the SOLID lines ONLY. Do they fit together easily yet?
6. What must be removed in order for them to easily fit together like a puzzle?
7. What would be the chemical formula for maltose?
8. How does the formula for sucrose compare to that of maltose?
POLYSACCHARIDES:
MANY SUGAR MOLECULES: Ex: starch, glycogen, cellulose, chitin
1. Construct a starch molecule by joining 3 glucose paper models. (Starch
actually consists of hundreds of glucose molecules.) What must be removed
from the glucose paper models in order for them to easily fit together?
2. The molecular formula for a polysaccharide is written as (C 6H10O5) n. The n
represents the number of times the basic group is repeated. How many times
larger is the number of hydrogen atoms than oxygen atoms in a
polysaccharide molecule?
3. What is the smallest number of glucose molecules that could form a
polysaccharide?
ANALYSIS/CONCLUSION QUESTIONS:
1.
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7.
Name 3 categories of carbohydrates.
What 3 elements are present in all carbohydrates?
Name 2 monosaccharides.
Name 2 disaccharides.
Name 2 polysaccharides.
What molecules combine to form disaccharides?
What ends of monosaccharides are removed to form disaccharides and
polysaccharides?
8. The word “carbohydrate” is derived from “carbon” and “water”. Explain why
this correctly describes this molecule.