Nucleic Acid Directions
1. Read the background information below about carbohydrates and use it to answer the
accompying questions.
Nucleic Acids are the primary genetic molecule for all living things. All living things have both
types of nucleic acid polymers, which work together to define what they are. Deoxyribose Nucleic
Acid (DNA) is the primary genetic code holder. In prokaryotes it is found in the cytoplasm of the
cell and in Eukaryotes it is housed in the Nucleus. We will focus more on the exact structure of
DNA in later units. For now you need to know that segments of DNA make up codes, called
genes. Each gene is responsible for making a protein. The proteins that the genes make
determine the traits of an organism.
Ribose Nucleic Acid (RNA) is the other Nucleic Acid. RNA is a little different from DNA and there
are many types that we will learn about in later units. The main basic function of RNA is to
convert the DNA code (gene) into a protein. RNA works as an intermediate between the DNA and
the ribosome to help make the protein. This will be discussed further in later units.
Even though RNA and DNA have some differences they are still each Nucleic Acids. Therefore,
they still contain similar monomers. The monomers of DNA and RNA are called nucleotides. This
is easy to remember because Nucleic Acids, nucleotides, nucleus, DNA, and RNA all have “Nuc”
in the word. Since RNA and DNA are polymers they are made of millions of nucleotides put
together. We are going to just concentrate on identifying the parts of the nucleotides and how the
nucleotide are put together in this exercise.
2. Answer questions 1-6
3. Take the Nucleotide piece shown below.
4. First we are going to identify the parts of a nucleotide.
5. Look at the circle/oval shape at the top left part of the nucleotide. Sketch just this part in number
7. Make sure to include the elements present.
6. This part is called the phosphate group. We will always show this part of the nucleotide as a
circle. The phosphate group helps to form the backbone of the nucleic acid, because when all the
nucleotides are put together the phosphates are one part on the outside of the molecule.
7. Answer question 8.
8. Look at the pentagon around the letter D on the nucleotide. Sketch just the pentagon in number
10. Make sure to include the elements present.
9. This part that you sketched in number is called the sugar. Since you are working with DNA the
sugar is called deoxyribose. Notice how the ring structure is very similar to what you were
drawing when you sketched your carbohydrates. We will always show this part as a pentagon (a
house looking shape). This sugar also makes up the backbone of the nucleic acid along with the
phosphate, because it is on the outside of the molecule.
10. Answer question1 10-11.
11. Finally look at the third part in the upper right hand corner of the nucleotide, attached to the sugar.
Notice how you can remove this piece. This piece will either have the letter G, C, A, or T on it.
Now find the other pieces that have the other letters on your table.
12. The four parts you sketched above are called the bases. There are four different bases. A stands
for adenine, T stand for thymine, C stands for cytosine, and G stands for guanine. That bases are
key part of DNA. If a bunch of nucleotides were put together the bases can be arranged in
numerous ways. It is the sequence (order) of these bases that determines our genes. For
example, ATC sequence will code for a different protein than ACG. We will discuss this further in
later units.
13. Answer questions 12.
14. Now move just your bases around and try to connect them to each other using the side with the
squigglies on them.
15. Answer question 13.
16. Now that we discovered the parts of the nucleotides you will create a polymer (DNA).
17. Put a base onto a sugar. You just made a nucleotide. Sketch the nucleotide in number 14. On
the nucleotide label the phosphate, sugar, and base.