Name: ______Biochemistry
Date: ______Carbohydrates
Part 1: Carbohydrate Models
There are three different groups of carbohydrates. They are called monosaccharides, disaccharides, and polysaccharides. “Saccharide” means sugar.
Group 1. Monosaccharides (single sugar molecules)
A single molecule sugar is called a monosaccharide. The prefix “mono-“means one. However, the one molecule can have different shapes due to a different arrangement of atoms. Three monosaccharides are glucose, fructose, and galactose.
- Examine the structural formulas of these three sugars (Figure 1) and answer questions 1 to 6.
1)What three chemical elements are present in the three monosaccharides shown? Note the letter “C” stands for carbon, “H” stands for Hydrogen, and “O” stands for oxygen. ______
2)How many atoms of carbon are present in a molecule of
Glucose? ______
Fructose? ______
Galactose? ______
3)Add subscripts to the following to indicate the proper simple formula. Fill in the blanks by counting the total number of carbon, hydrogen and oxygen atoms in each molecule.
Glucose C___H___O____
Fructose C___H___O____
Galactose C___H___O____
4)Are there two times as many hydrogen atoms in a molecule of
Glucose? ______
Fructose? ______
Galactose? ______
5)Are there two times as many hydrogen atoms as oxygen atoms in a molecule of water? ______
- Compare the structural formula of glucose to fructose?
6)Are they exactly the same shape? ______
7)Are they both monosaccharides? ______
Group 2: Disaccharides (double molecule sugars)
Two monosaccharide sugar molecules can join chemically to form a larger carbohydrate molecule called a double sugar, or disaccharide. The prefix “di” means two. By chemically joining a glucose molecule with a fructose molecule, a double sugar called sucrose is produced.
Use the page of paper models given to you by your teacher to complete this section.
1)Cut out a model of one glucose and one fructose molecule. Cut along solid lines only. Attempt to join the two molecules like puzzle pieces.
- Do the glucose and fructose fit together easily to form a sucrose molecule? ______
In order to join the molecules, remove an –OH end from one molecule and an –H end from another. Cut along dotted lines.
2)Removing the –H and the –OH ends can also fit together to form a molecule. This new molecule has a simple formula of ______and is called ______.
3)Write the simple formula for sucrose by adding together the molecular formulas for glucose and fructose and then subtracting water. ______
Different disaccharide molecules can be made by joining other monosaccharides in different combinations. By chemically joining a glucose molecule with another glucose molecule, a double sugar called maltose is formed.
- Cut out and attempt to join the two new glucose model molecules like puzzle pieces.
4)What must be removed from the glucose model molecules so that they easily fit together? ______
5)Write the simple formula for maltose? ______
6)How does the simple formula for sucrose compare to maltose?
- Are there 2 times as many hydrogen atoms as oxygen atoms in a disaccharide? ______
- How many monosaccharide molecules are needed to form one sucrose molecule? ______
- How many monosaccharide molecules are needed to form one maltose molecule? ______
Group 3. Polysaccharides (many molecule sugars)
Just as double sugars were formed from two simple sugar molecules, polysaccharides are formed when many single sugars are joined chemically. The prefix “poly” means many. Starch, glycogen, and cellulose are the three most common polysaccharides in biology. They consist of long chains of glucose molecules joined.
- Construct a starch molecule by joining three glucose molecules. This model will represent only a small part of a starch molecule because starch consists of hundreds of glucose molecules.
1) What must be removed from the glucose model molecules in order to have them easily fit together? ______
The simple formula for a polysaccharide is written as
(C6H10O5) n. The n equals the number of times the C6H10O5 group is repeated. You can see this group as the middle glucose of your model. Remember the –H and –OH ends of the middle molecule are missing.
Name: ______Carbohydrate Answer Sheet
Date: ______
Group 1:
1) ______
2) ______
3) ______
4) ______
5) ______
6) ______
7) ______
Group 2
1) ______
2) ______
3) ______
4) ______
5) ______
6) ______
Group 3
1) ______
Combining Amino Acids to Form Protein
Amino acids are not protein molecules. They are the only the “building blocks” of protein. Several amino acids must be chemically joined in a chain to form a protein molecule. We can show how Aamino acids join by using models.
Use the paper models given to you by your teacher to complete this section.
- Cut out the four amino acid models. Cut along the solid lines only. Attempt to join the amino acids.
7)Can the amino acid models easily join to form a protein molecule?
- Join the molecules by removing as many –OH groups and –H groups as needed from the amino acids. All four amino acid molecules can be joined in this manner to form a protein. Join them in the order valine-threonine-alanine-glycine.
- Join the leftover -H and –H ends.
8)What chemical substance is formed when the –OH’s and –H’s are joined?
9) How many molecules of water are formed when four amino acids join?
10)What chemical compound is formed when the four amino acids are joined?
11)Describe the difference between an amino acid molecule and a protein molecule.
There are thousands of different proteins in living organisms. What makes each protein different is the order, number, kind, and arrangement in space of amino acids joined. You only assembled four amino acids into a protein using a specific order.
12)Construct two proteins different from the one you made above. List the order of amino acids here.
(A)______
(B)______
Combing Glycerol and Fatty Acids to Form Fats
A fat molecule consists of one glycerol molecule and three fatty acid molecules joined.
- Cut out the glycerol and fatty acid model molecules given to you by your teacher. Cut along the solid lines only. Attempt to construct a fat molecule.
13)Will the fat molecule fit together as pieces in a puzzle?
- Remove three –OH ends from the glycerol molecule and three –H ends from the fatty acids. Now join the molecule to form a fat.
14)(a) How many glycerol molecules are needed to form a fat molecule?
(b) How many fatty acid molecules are needed to form a fat molecule?
16) What chemical substance is formed when the –H and –OH ends are joined?______
Production of a fat molecule is a chemical reaction. A chemical shorthand way of expressing the formation of a fat is as follows:
Glycerol + Fatty Acid Molecules- Fat + Water
15)How many water molecules are formed when one fat molecule is produced?
Many fats exist in living things. The wide variety of fats are formed by different combinations of fatty acid molecules.
16)A change in the type of fatty acid results in a different type of a fat molecule. What molecule remains unchanged in all fats? ______
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