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/biolog
y/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 number
of 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/i
ndex2.html
• Quiz on these scientists Monday!
• Matching format