CK-12 Physical Science Concepts - For Middle School

3.40. Nucleic Acid Classification http://www.ck12.org

Summary

1. Nucleic acids are one of four classes of biochemical molecules. Nucleic acids include RNA (ribonucleic acid)
   and DNA (deoxyribonucleic acid).


2. Nucleic acids consist of chains of small molecules called nucleotides, which are held together by covalent
   bonds.


3. RNA is made of one nucleotide chain, and DNA is made of two. The two chains of DNA are held together by
   hydrogen bonds in the shape of a double helix.


4. DNA contains the genetic code, which instructs cells how to make proteins. RNA copies the genetic code in
   DNA and helps synthesize proteins based on the code.

Vocabulary

• nucleic acid: Biochemical compound (either DNA or RNA) that contains oxygen, nitrogen, and phosphorus
  in addition to carbon and hydrogen; consists of one or two long chains of smaller molecules called nucleotides.

Explore More

Watch the video about DNA at the following URL, and then answer the questions below.

http://www.hhmi.org/biointeractive/paired-dna-strands

1. What are the complementary bases in DNA?


2. Assume that one of the nucleotide chains in a DNA molecule has the following sequence of bases: ATCGGC-
   TAAC. What is the sequence of bases on the other nucleotide chain of the molecule?

Review

1. What are nucleic acids? What are the two types of nucleic acids?


2. Describe the structure of a nucleotide.


3. What holds nucleotides together in a nucleic acid?


4. Compare and contrast the structure and functions of DNA and RNA.