1. Chapter 4 Nucleic Acids and the RNA World

2. Key Concepts Nucleotides consist of a sugar, a phosphate group, and a nitrogen-containing base. Ribonucleotides polymerize to form RNA. Deoxyribonucleotides polymerize to form DNA. DNA’s primary structure consists of a sequence of nitrogen-containing bases. Its secondary structure consists of two DNA strands, running in opposite directions, that are held together by complementary base pairing and twisted into a double helix. DNA structure allows organisms to store and replicate the information needed to grow and reproduce.

3. Key Concepts, cont’d RNA’s primary structure consists of a sequence of nitrogen-containing bases. Its secondary structure includes short regions of double helices and structures called hairpins. Because RNA molecules can carry information as well as catalyze chemical reactions, it is likely that RNA was the first self-replicating molecule and a forerunner to the first life-form.

4. DNA Structure http://highered.mcgraw- hill.com/sites/0073383198/student_view0/cha pter2/animation_quiz_-_dna_structure.html

5. RNA Structure & the Origin of Life http://www.nature.com/scitable/content/rna- has-a-primary-and-secondary-structure- 105312 http://exploringorigins.org/rnaworld.html

6. Website Questions (send questions to desparza@episd.org) 1. Describe 3 structural differences between DNA and RNA. 2. Describe 1 functional difference between DNA and RNA. 3. What is a ribozyme? How is it similar AND different than an enzyme? 4. Why do scientists say that RNA was important in the creation of life on earth?