| DNA Structure and Function
Chapter 8 (McDougal- Littell) Activity #1: Identifying DNA as the Genetic Material Insert notes here from DNA Timeline (PBS) and text pg. 226 What did we know about genetics before 1945? Mendel? Miescher? Griffith? Avery? What did we know about genetics from 1945 to 1966? Pauling? Chargaff? Hershey & Chase? Watkins & Franklin? Watson & Crick? What did we know about genetics from 1966 to 1985? Nirenberg et al? Berg? Mullis? What did we know about genetics from 1985 to 2003? Collins & Tsai? 1) Explain Griffith�s �transforming� investigation. What did he do? What did his results show? 2) Explain what Avery did. What did his experiment show? 3) What did Hershey and Chase confirm? 4) Thinking Question: What two processes in meiosis lead to genetic variation? 5) What were Rosalind Franklin�s main accomplishments (in relation to DNA structure)? Pg. 231 textbook. You are going to see in this chapter how a few simple molecules can lead to the formation of diverse complex molecules. Activity #2: The Structure of DNA The fundamental unit of a nucleic acid is a nucleotide. The structure of a nucleotide is shown to the right: 1) Please copy down the basic-structure of a nucleotide and label the three major portions: the phosphate group, the 5-carbon sugar, and the nitrogen base. 2) By chemical means, hundreds upon hundreds of nucleotides may join to form a strand of nucleic acid. DNA occurs as a �ladder�- like double strands of nucleotides (page 233, fig 8.7) Please sketch the pairings of nucleotides showing me a �ladder� with nitrogen bases as the �rungs� of a ladder. 3) If the ladder is twisted as in fig. 8.7, it forms a double helix. It is the sequence or order of the groups of nitrogen bases, which make up the instructions to the cell. 4) Please answer the reviewing the main ideas questions 1-5 pg. 233. Activity #3: Nitrogen Bases and Hydrogen Bonds 1) What are the 4 types of Nucleotides found in DNA? Please sketch them and label each one. 2) How are Adenine and Guanine similar? 3) How are Thymine and Cytosine similar? 4) Take a look at Adenine (Fig. 8.7). How many hydrogen bonds will form with Thymine? 5) Take a look at Guanine. How many H- bonds will form with Cytosine? A and T are complimentary pairs�C and G are complimentary pairs. Activity #4: Base Pairings (You try it!) 1) Draw the DNA structure for this strand 5� � CCGAATTGC� 3� First, figure out the complimentary strand. Next, align the complimentary base pairs by drawing the phosphate groups, the sugar, and then the nitrogen base. 2) Make sure I see the correct number of hydrogen bonds! Activity #5: Genes and the DNA Code Last unit, we learned that genes carry information about inherited traits. 1) Using reasoning, which of the 3 parts of a nucleotide (sugar, phosphate, or nitrogen base) would carry the genetic code? 2) It is estimated that there are about 6 billion �rungs� in the DNA molecule of a human chromosome. If the average gene consists of about 200 base pairs (rungs), how many genes would there be in a DNA molecule with 6 billion rungs? Show me your calculations! 3) Now that you have studied the structure of DNA, how would one gene differ chemically from another gene? |