Question

1. Use the following information to complete the chart below:

Element	Atomic mass
Carbon	12
Oxygen	16
Hydrogen	1
Nitrogen	14
Phosphorous	31

	Molecule	Molecular weight
a	H2O
b	C6H12O6
c	CO2
d	C12H22O11
e	C9H18O2
f	C4H3O2N3

2. Which of the molecules in question #1 are macromolecules? Give a reason for your

answer.

3. Which of the molecules in question #1 are carbohydrates? Explain
4. Which of the molecules in question #1 could be a lipid molecule? Explain
5. Which of the molecules in question #1 could be a part of a part of a protein molecule? Explain

Answer 1

Formula for Molecular Weight of any molecule

M.W. = Sum of (Number of atoms of an element x Atomic weight of element)

where M.W. = Molecular Weight of Compound

Calculation of M.W. of molecules :

a. M.W of H2O = 2 x 1 + 1 x 16 = 2 + 16 = 18 Da

b. M.W. of C6H12O6 = 6 x 12 + 12 x 1 + 6 x 16 = 72 + 12 + 96 = 180 Da

c. M.W. of CO2 = 1 x 12 + 2 x 16 = 12 + 32 = 44 Da

d. M.W. of C12H22O11 = 12 x 12 + 22 x 1 + 11 x 16 = 144 + 22 + 176 = 342 Da

e. M.W. of C9H18O2 = 9 x 12 + 18 x 1 + 2 x 16 = 108 + 18 + 32 = 158 Da

f. M.W. of C4H3O2N3 = 4 x 12 + 3 x 1 + 2 x 16 + 14 x 3 = 48 + 3 + 32 + 42 = 125 Da

	Molecule	Molecular weight
a	H2O	18 Da
b	C6H12O6	180 Da
c	CO2	44 Da
d	C12H22O11	342 Da
e	C9H18O2	158 Da
f	C4H3O2N3	125 Da

1. Macromolecules are called so because they contain a large number of number of atoms and are composed of several small fundamental subunits called monomers. These monomers fuse to form a complex macromolecule. In biology , we generally encounter four such macromolecules - Protein, Carbohydrate, Lipid and Nuclei Acid.

Here Molecule b, d e and f are glucose, sucrose, ethyl-hepatanoic acid and a part of protein respectively. These molecules are contain a large number of carbon,hydrogen , oxygen and nitrogen . These compounds also form the fundamental subunits of macromolecules.

2. Here Molelcule b and d are carbohydrates.

Explanation :

Carbohydrates are biomolecules which are composed of carbon , hydrogen and oxygen. They are polyhydroxy aldehydes or polyhydroxy ketones. In carbohydrates, Hydrogen and Oxygen atoms are present in a ratio of 2 :1 as in water. This is why they are called hydrates of carbon or Carbohydrates. In case of molecule b and d we can see that the ratio of hydrogen to oxygen atoms is 2 : 1. Thus they are carbohydrates.

3. Molecule e is a lipid molecule.

Explanation :

It is so because it has a long chain of methyl groups with a carbon atom to hydrogen atom ratio of 1:2. In addition it appears to have a carboxyl terminal.

4. Molecule f could be a protein molecule.

Explanation :

Proteins are composed of amino acids . Amino acids are compounds containing carbon , hydrogen , oxygen and most importantly nitrogen. Since they contain nitrogen, they are called amino acids. Since proteins contain amino acids, they are called nitrogenous compounds. Here molecule f is the only molecule containing a nitrogen. Thus it can be a part of protein molecule.