- Nucleotides
- DNA and RNA
- The DNA double helix
1. There are two types of nucleic acids in living things: DNA and RNA. They are both made of nucleotides. However, the nucleotides in DNA differ a little bit from those in RNA. In chapter 2 of your textbook, read the section on nucleic acids, focusing on subsections "DNA" and "RNA." Study lecture notes on DNA and RNA. After you have learned the differences between DNA and RNA, copy the table below in your notebook and try to fill it in without looking at your text or notes. Once you have filled it in, mouse over the word "ANSWER" below the table. If you did not get all the answers correctly, study your text and notes and try it again.
Nucleotides are the monomers that make up nucleic acids. Each nucleotide is made of a nitrogenous base, a 5 carbon sugar (a pentose), and a phosphate.
ANSWER
2. Nucleotides in nucleic acids are connected in a specific way. In order to understand how nucleic acids are replicated and how they perform their function, you need to understand how nucleotides connect to each other. Study the relevant material in your lecture notes and take a look at figure 8.3 in your textbook. Review the section on DNA in chapter 2. Once you have learned the material, you should be able to answer the following questions:
- What is the name of the bond that connects two nucleotides in a nucleic acid?
- What groups from two nucleotides participate in the formation of that bond?
- Where are the groups participating in the formation of the bond attached (to which carbon atoms)?
3. Close your book and on a piece of paper, try to link the following 4 nucleotides to form a single strand of a nucleic acid with the sequence ACAA. Once you have done that, check your diagram by mousing over the word ANSWER below. If you did not get it right, revisit the textbook and your notes and try it again. By the way, can you tell what type of nucleic acid this is (DNA or RNA)?
ANSWER
4. Because of how nucleotides are connected, all nucleic acids have a direction. Review the section on nucleic acid in chapter 2 of the textbook, as well as your lecture notes. You should know the answer to the following questions:
- How do we denote the two ends of a nucleic acid?
- When talking about the two ends of a nucleic acid, what do numbers refer to?
- What is the accepted default direction of a nucleic acid?
- What groups are found at the two ends of a nucleic acid?
- Look at the nucleic acid chain you made (AACA) above. Identify the two ends of that chain and label them.
5. If you feel that you have mastered the concepts on this page, you can move to the next topic, which discusses the detailed structure of DNA.