1. 12.1 The Genetic Material Objective:
6(A) Identify components of DNA, and describe how information for specifying the traits of an organism is carried in the DNA

2. 6(A) Identify components of DNA, and describe how information for specifying the traits of an organism is carried in the DNA.
1(A) Demonstrate safe practices during laboratory and field investigations.
2(C) know scientific theories are based on natural and physical phenomena and are capable of being tested by multiple independent researchers. Unlike hypotheses, scientific theories are well-established and highly-reliable explanations, but they may be subject to change as new areas of science and new technologies are developed
3(A) In all fields of science, analyze, evaluate, and critique scientific explanations by using empirical evidence, logical reasoning, and experimental and observational testing, including examining all sides of scientific evidence of those scientific explanations, so as to encourage critical thinking by the student.
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DNA: The Genetic Material

3. 4(A) Compare and contrast prokaryotic and eukaryotic cells.
3(E) Evaluate models according to their limitations in representing biological objects or events.
3(F) Research and describe the history of biology and contributions of scientists
4(A) Compare and contrast prokaryotic and eukaryotic cells.
6(B) Recognize that components that make up the genetic code are common to all organisms.
9(D) Analyze and evaluate the evidence regarding formation of simple organic molecules and their organization into long complex molecules having information such as the DNA molecule for self-replicating life.
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DNA: The Genetic Material

4. Essential Questions
Which experiments led to the discovery of DNA as the genetic material?
What is the basic structure of DNA?
What is the basic structure of eukaryotic chromosomes?
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DNA: The Genetic Material

5. Vocabulary Review New nucleic acid double helix nucleosome
DNA: The Genetic Material
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6. Discovery of the Genetic Material
After the rediscovery of Mendel’s work, scientist began to look for the molecule involved in inheritance.
For many years, scientists struggled to determine if DNA or protein was the source of genetic information.
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DNA: The Genetic Material

7. Discovery of the Genetic Material
Griffith’s Experiment
First major experiment searching for the genetic material.
Involved transformation between two forms of S. pneumoniae
Set the stage for the search to identify the transforming substance
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DNA: The Genetic Material

8. Discovery of the Genetic Material
Avery’s Work
Identified the molecule that transformed the R strain of S. pneumoniae into the S strain
Concluded that when the S cells were killed, DNA was released
R bacteria incorporated this DNA into their cells and changed into S cells
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DNA: The Genetic Material

9. Discovery of the Genetic Material
Hershey and Chase’s Experiments
Used radioactive labeling to trace bacteriophage DNA and protein.
Concluded that the bacteriophage DNA was injected into the cell and provided the genetic information needed to produce new viruses.
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DNA: The Genetic Material

10. DNA Structure Nucleotides
Nucleotides are the subunits of nucleic acids, and consist of
5-carbon sugar
Phosphate group
Nitrogenous base
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DNA: The Genetic Material

11. DNA Structure Chargaff
Analyzed the amount of A, G, T, and C in the DNA of various species
Chargaff’s rule: C = G and T = A
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DNA: The Genetic Material

12. DNA Structure The structure question
Search for the structure of DNA was lead by four scientists:
Rosalind Franklin, British chemist
Maurice Wilkins, British physicist
Francis Crick, British physicist
James Watson , American biologist
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DNA: The Genetic Material

13. DNA Structure X-ray diffraction
X-ray diffraction techniques indicated that DNA was a double helix, or twisted ladder shape.
The double helix shape was formed by two strands of nucleotides twisted around each other.
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DNA: The Genetic Material

14. DNA Structure Watson and Crick
Using Franklin and Chargaff’s data, Watson and Crick measured the width of the helix and the spacing of the bases.
They built a model that conformed the Franklin and Chargaff’s data.
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DNA: The Genetic Material

15. DNA Structure DNA structure DNA often is compared to a twisted ladder.
Rails of the ladder are represented by the alternating deoxyribose and phosphate.
The pairs of bases (cytosine-guanine or thymine-adenine) form the steps.
Purine base always binds to a pyrimidine base
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DNA: The Genetic Material

16. DNA Structure Orientation
DNA molecules have specific orientations of the two strands
On the top rail, the strand is said to be oriented 5’ to 3’.
The strand on the bottom runs in the opposite direction and is oriented 3’ to 5’.
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DNA: The Genetic Material

17. Chromosome Structure
In prokaryotes, DNA molecules are contained in the cytoplasm, and consist mainly of a ring of DNA and associated proteins.
In eukaryotes, DNA is organized into individual chromosomes.
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DNA: The Genetic Material

18. Chromosome Structure
To fit into a cell, DNA coils around a group of beadlike proteins called histones.
DNA + histones form a nucleosome, which group together into chromatin fibers, which supercoil to form a chromosome.
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DNA: The Genetic Material

19. Review Essential Questions Vocabulary
Which experiments led to the discovery of DNA as the genetic material?
What is the basic structure of DNA?
What is the basic structure of eukaryotic chromosomes?
Vocabulary
double helix
nucleosome
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DNA: The Genetic Material