LAB: Modeling Life’s Important Compounds

As you study the important molecules of living things, it is helpful to be able to visualize how they look.

Today you will be building models of these various molecules. You will also model the processes by which these molecules are formed.

Each group will pick up two bags each of the following model components:

Carbon atoms: black 4 pronged piece

Hydrogen atoms: white 1 pronged piece

Oxygen atoms: red 2 pronged piece

Nitrogen atoms: blue 3 pronged piece

Chemical bonds: white rubber straws

You will be making a series of molecules. As you build the molecules your teacher will need to look over them and initial the boxes indicating successful completion. If you have to wait for her to get to your station, be patient and keep building the next one until she gets there.

A single bond is made by inserting one white rubber straw into a prong on one of the atoms. A double bond is made by connecting two white rubber straws between two atoms which are able to double bond to each other.

NUCLEIC ACIDS

Nucleic acids are the most important of the macromolecules, as they are the molecules responsible for storing and transmitting hereditary information from cell to cell. There are two types of nucleic acids: DNA (deoxyribonucleic acid) and RNA (ribonucleic acid). Nucleic acids are long chain polymers made up of nucleotides. A nucleotide is composed of three parts: a 5 or 6 carbon sugar, a nitrogen base and a phosphate group.

The nitrogen bases in DNA and RNA fall into two categories: purines and pyrimidines. Purines contain two carbon rings fused to one another. Pyrimidines are constructed of a single carbon ring. The nitrogen bases are named as follows:

Nucleic Acid / Purines / Pyrimidines
DNA / guanine, adenine / cytosine, thymine
RNA / guanine, adenine / cytosine, uracil

Note that in RNA, there is no thymine, and uracil takes its place.


Construct the following nitrogen bases:

Guanine:
/ Thymine:

There are also two different sugars that make up each nucleic acid: deoxyribose and ribose. Each is a five-carbon sugar; however, deoxyribose has one fewer oxygen atom than ribose does.

Construct the sugars shown below:

Deoxyribose:
/ Ribose:


Analysis Questions

1.  Give a biological function for each of the following molecules:

  1. Proteins: ______
  2. Carbohydrates: ______
  3. Lipids: ______
  4. Nucleic Acids: ______

2.  What are the monomers that make up the following molecules:

  1. Proteins: ______
  2. Carbohydrates: ______
  3. Lipids: ______
  4. Nucleic Acids: ______

3.  Describe the structure of a saturated fatty acid. How does putting a double bond in the carbon chain affect the structure of the fatty acid? ______

4.  Describe the process by which macromolecules are formed and name the specific reaction. ______

______

5.  Describe the process by which macromolecules are broken down into their monomers and name the

specific reaction. ______

______
______

6. What are functional groups, and which two are found in all amino acids? ______

______

______

7. Describe the structural differences between saturated and unsaturated fatty acids, and explain how such differences contribute to the physical properties of each molecule.______

______

______

Mills 2010 Modeling Life's Important Compounds-IB

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