Biology – The Continuity
of Life

Objective 1
– Describe and model the structure of
DNA
DNA
Stands for:
Deoxyribonucleic Acid
Function:
Stores genetic information
Structure:
Monomers (individual units)
are called: Nucleotides
DNA

Nucleotides Three Parts:
1. 5 Carbon Sugar
Deoxyribose
2. Phosphate Group
3. Nitrogen Base
Adenine
Thymine
Guanine
Cytosine
Scientists

Griffith
– Observed a “Transforming” factor could be
passed between bacteria

Avery
– DNA stores and transmits genetic info

Hershey & Chase
– Concluded that genetic material is DNA and
not a protein
Scientists (continued)

Chargaff
– Found that the amount of A = T and the
amounts of C = G

Franklin and Wilkins
– Studied DNA’s structure using X-ray
diffraction
James Watson and
Francis Crick




Used the existing information to put
together the “Double Helix” structure
of DNA.
DNA is double stranded
Phosphate & sugar on outside
Nitrogen Bases on the inside
Watson-Crick Model of DNA Structure
Hydrogen bonds form
between
complementary bases
DNA is a double helix Complementary base
of two nucleotide
pairs hold the two DNA
strands
strands together