Summary Chapter 9 - Molecular Structure of DNA and RNA

Chapter 9 Molecular structure of DNA and RNA

9.1 Identification of DNA as the genetic material

Genetic material must meet four criteria:
1. Information
2. Transmission: The DNA must be passed to offspring
3. Replication: DNA must be copied, in order to be passed on.
4. Variation

Experiments that suggested that DNA is genetic material:
Frederick Griffith (1928):
- Showed that genetic material from type S bacteria could transform type R bacteria
into type S.
- Griffith called the process transformation.
- See figure 9.1

Avery, MacLeod and McCarty:
- They tried to identify the transforming principle.
- They found out that the transforming material was the DNA of the bacteria.
- See figure 9.2

Hershey and Chase (1952):
- Used bacteriophage to find out what the genetic material in the virus T2 was.
- Came to the conclusion that this genetic material was also DNA.

9.2 Overview of DNA and RNA structure

DNA and RNA are known as nucleic acids. This term is derived by Friedrich Miescher in
1869. He identified a novel phosphorus-containing substance that was isolated from the
nuclei of white blood cells. When the structure of DNA became better understood, it was
determined that they are acid molecules, which means they release hydrogen ions.

The complexity of DNA:
1. Nucleotides
2. Strand of DNA (multiple nucleotides linked together)
3. Double helix (two strands of DNA)
4. Three-dimensional structure of DNA




9.3 Nucleotide structure