The Structure and Function of DNA: A Comprehensive Guide

1. Who Discovered the Genetic Material?

Frederick Griffith

2. When Was the Genetic Material Discovered?

1928

3. What Did Frederick Griffith Do With His Major Experiment?

He studied two strains of the bacteria Streptococcus pneumoniae which causes pneumonia. He found that one strain could be transformed, or changed into the other form.

4. What Did Avery and Colleagues Identify?

They identified the molecule that transformed the R strain of bacteria into the S strain.

5. What Did Hershey and Chase Publish in 1952?

They published results of experiments that provided definitive evidence that DNA was the transforming factor.

6. How Does a Virus Replicate?

Viruses cannot replicate themselves; they must inject their genetic material into a living cell to reproduce.

7. Explain Radioactive Labeling

It is used to trace the fate of the DNA and protein as the bacteriophage infected and reproduced.

8. What is the Tracking DNA?

The viral DNA was injected into the cell and provided the genetic information needed to produce new viruses. This experiment provided powerful evidence that DNA, not protein, was the genetic material that could be passed from generation to generation in viruses.

9. What Is the Name of the Biochemist Who Determined the Basic Structure of Nucleotides?

P.A. Levene

10. What Are Nucleotides?

Nucleotides are the subunits of nucleic acids and consist of a five-carbon sugar, a phosphate group, and a nitrogenous base.

11. What Are the Two Nucleic Acids Found in Living Cells?

DNA and RNA

12. What Do DNA Nucleotides Contain?

They contain the sugar deoxyribose, a phosphate, and one of four nitrogenous bases: adenine, guanine, cytosine, or thymine.

13. What Do RNA Nucleotides Contain?

They contain the sugar ribose, a phosphate, and one of four nitrogenous bases: adenine, guanine, cytosine, or uracil.

14. What Did Erwin Chargaff Analyze?

He analyzed the amounts of adenine, guanine, cytosine, and thymine in DNA.

15. What Did Chargaff's Data Show?

Data showed that though base composition varies from species to species, within a species, the amount of adenine equals the amount of thymine, and the amount of cytosine equals the amount of guanine.

16. What Is Chargaff's Rule?

C=G and T=A

17. What Is X-Ray Diffraction?

A technique that involved aiming X-rays at the DNA molecule.

18. What Did Photo 51 Indicate?

It indicated that DNA was a double helix, or twisted ladder shape, formed by two strands of nucleotides twisted around each other.

19. What Is DNA?

DNA is the genetic material of all organisms, composed of two complementary, precisely paired strands of nucleotides wound in a double helix.

20. What Are the Features That Watson and Crick's Model Has?

• Two outside strands consist of alternating deoxyribose and phosphate.
• Cytosine and guanine bases pair to each other by three hydrogen bonds.
• Thymine and adenine bases pair to each other by two hydrogen bonds.

21. Describe DNA

DNA often is compared to a twisted ladder represented by the alternating deoxyribose and phosphate.

22. What Are Pyrimidines?

Cytosine and thymine

23. What Are Purines?

Adenine and guanine

24. What Is Orientation?

Another unique feature of DNA molecules is the direction, or orientation, of the two strands.