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Transcript of DNA Structure
1. Frederick Griffith
-Genetic information could be transferred from one bacterium to another (transformation).
2. Oswald Avery
-Did same experiment as Griffith but wanted to know what molecule in the heat-killed bacteria was responsible for the transformation. Discovered that DNA was the molecule, not protein.
-Determined that genes are composed of DNA by using radioactive markers.
4. Rosalind Franklin
-Studied the structure of DNA using X-Ray Diffraction. Results showed that the structure was in the form of a helix.
5. Watson and Crick
-First to develop the model of the structure of DNA (Nobel Prize).
Structure of DNA
-Double-Helix (Twisted Ladder).
DNA is made up of Nucleotides.
Nucleotides have three parts:
1. Sugar (Deoxyribose)
3. Nitrogen base
States that DNA from any cell of all organisms should have a 1:1 ratio of purines and pyrimidines.
More specifically the number of Adenine should equal the number of Thymine, and the number Cytosine should equal the number of Guanine.
%A = %T and %G = %C
Example: If 3,000 Thymines are in a sample of DNA,
then there would also be 3,000 Adenines.
The Nucleotide (Building block of DNA)
-Nucleotides are the monomers that build
a DNA molecule.
-Consists of a sugar, phosphate and base.
Purines (Double Ring):
-Adenine & Guanine
Pyrimidines (Single Ring):
-Cytosine & Thymine
DNA Structure &
Purines bond with Pyrimidines
Purines can't bond with other Purines
A always pairs with T, and C always pairs with G
DNA, Chromosomes, and Genes
DNA: The Instructions
Chromosomes: Wound up DNA
Genes: Section of DNA that codes for
the production of a protein.
There are 4 kinds of nitrogenous bases:
The backbone of DNA consists of
alternating sugar and phosphates.
The bases (4) are in the middle.
1. Who first noticed the shape of the DNA molecule?
2. Who got credit for creating the first model of the DNA molecule?
3. What is the shape a DNA molecule makes?
4. What is the monomer called that makes up a DNA molecule?
5. What are the 3 parts of a nucleotide?
5. What are the 4 bases?
6. Which two bases are Pyrimidines? Purines?
7. What type of bond holds the two strands together?
8. What is the difference between deoxyribose and ribose sugar?
9. The backbone of DNA consists of?
10. True or False: The number of thymines must equal the number of adenines.
11. True or False: Purines will bond with other Purines.