1. The Structure of DNA What is genetic material composed of?
What experiments helped identify the role of DNA?
What is the shape of a DNA molecule?
How is information organized in a DNA molecule?
What scientific investigations led to the discovery of DNA’s
structure?

2. DNA: The Genetic Material
DNA is the primary material that causes recognizable, inheritable characteristics in related groups of organisms.

3. Searching for the Genetic Material
Three major experiments led to the conclusion that DNA is the genetic material in cells.
These experiments were performed by Griffith, Avery, Hershey, and Chase.

4. Griffith
Griffith’s experiments led to the conclusion that genetic material could be transferred between cells.
But no one knew that this material was DNA.

5. Avery
Avery concluded that DNA is responsible for transformation of genetic material

6. Alfred Hershey and Martha Chase -1952
There finding indicated that rather than proteins, DNA is the hereditary material.

7. The Shape of DNA- James Watson and Francis Crick – mid fifties
A Winding Staircase V A DNA molecule is shaped like a spiral staircase and is composed of two parallel strands of linked subunits

8. Parts of the Nucleotide Subunits
Each nucleotide is made up of three parts:
a phosphate group,
a five-carbon sugar molecule,
and a nitrogen-containing base

9. phosphate groups
The phosphate groups and the sugar molecules of nucleotides link together to form a “backbone” for a DNA strand.

10. five-carbon sugar
The five-carbon sugar in DNA is called deoxyribose

11. nitrogen-containing base
The bases of nucleotides pair together to connect the two strands.

12. The Information in DNA
The information in DNA is contained in the order of the bases, while the base-pairing structure allows the information to be copied.

13. Nitrogenous Bases
The four kinds of bases, shown in are adenine (A), guanine (G), thymine (T), and cytosine (C).
Bases A and G are classified as purines.
Bases T and C are pyrimidines.

14. Base-Pairing Rules Adenine forms two hydrogen bonds with thymine
Cytosine forms three hydrogen bonds with guanine.

15. Complementary Sides
If the sequence of nitrogen bases on one strand is TATGAGAGT
sequence of bases on the other strand must be ATACTCTCA.