UNIT 2: Mechanisms of Inheritance

Topic: Structure of DNA

Journal Entry• We often see diagrams and models of DNA in

electronic and print media. How do you think scientists determined the structure of DNA?

Introduction to DNA

• DNA: deoxyribonucleic acid

•http://www.khanacademy.org/science/biology/v/dna

History of DNA

• 1871 - Friedrich Miescher isolated nucleic acids from the nuclei of white blood cells.

• 1888 -Walter Sutton and Theodor Boveri suggested that the genetic material of the cell is contained in chromosomes (chromosomal theory of inheritance).

• Chromosome: strand of genes that carry hereditary information (DNA)

• Centromere joins two identical copies of DNA called sister chromatids

• Found in the nucleus of our cells

• 1910 -Phoebus Levene showed that DNA and RNA are distinct nucleic acids, but both are composed of long chains of nucleotides.

• 1910 - Thomas Hunt Morgan et al. showed that genes are linear arrays on chromosomes.

• 1928 - Frederick Griffith performed experiments indicating that DNA is probably the genetic material of the cell.

• 1952 -Alfred Hershey and Martha Chase clearly showed that DNA is the genetic material of the cell.

• 1952 - Edwin Chargaff demonstrated that the number of adenines always equals the numberof thymines, and the number of cytosines always equals the number of guanines.

• Rosalind Franklin and Maurice Wilkins used X-ray crystallography to show the helical structure of DNA.

• James Watson and Francis Crick proposed the double-helix model of the DNA

DNA Model

• http://www.pbs.org/wnet/dna/dna_explorer/index2.html

• Quiz on these scientists Monday!• Matching format