1. IDENTIFICATION OF DNA AS THE GENETIC MATERIAL
To fulfill its role, the genetic material must meet several criteria
1. Information: It must contain the information necessary to make an entire organism
2. Transmission: It must be passed from parent to offspring
3. Replication: It must be copied
In order to be passed from parent to offspring
4. Variation: It must be capable of changes
To account for the known phenotypic variation in each species
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2. Griffith’s experiment on genetic transformation in S. pneumoniae

3. Avery et al also conducted the following experiments
To further verify that DNA, and not a contaminant (RNA or protein), is the genetic material
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4. Hershey and Chase Experiment with Bacteriophage T2
In 1952, Alfred Hershey and Marsha Chase provided further evidence that DNA is the genetic material
Inside the capsid
They studied the bacteriophage T2
It is relatively simple since its composed of only two macromolecules
DNA and protein
Made up of protein
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5. Protein capsid precariously attached on outside
Life cycle of the T2 bacteriophage
DNA inside of cell

7. Components of individual components of nucleotides

8. These atoms are found within individual nucleotides
However, they are removed when nucleotides join together to make strands of DNA or RNA
A, G, C or T
A, G, C or U
The structure of nucleotides found in (a) DNA and (b) RNA
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9. Structure of the building blocks of nucleic acids, nucleotides
Phosphates are attached here
Base always attached here
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10. The sugar-phosphate backbone
of nucleic acids with the protruding
bases

11. Contribution of Linus Pauling
In the early 1950s, he proposed that regions of protein can fold into a secondary structure
a-helix
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12. Contribution of Rosalind Franklin
She worked in the same laboratory as Maurice Wilkins
She used X-ray diffraction to study wet fibers of DNA
The diffraction pattern is interpreted (using mathematical theory)
This can ultimately provide information concerning the structure of the molecule
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13. Structure of Double stranded DNA
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16. DNA wound around histone proteins
Orders of compaction of DNA
DNA wound around histone proteins

17. Structure of RNA

18. Complementary regions Held together by hydrogen bonds
Secondary structures formed by RNA
Noncomplementary regions
Also called hair-pin
Have bases projecting away from double stranded regions
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19. For example Many factors contribute to the tertiary structure of RNA
Base-pairing and base stacking within the RNA itself
Interactions with ions, small molecules and large proteins
Molecule contains single- and double-stranded regions
These spontaneously interact to produce this 3-D structure
Tertiary structure of a tRNA
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