Origins of Molecular Biology &
Biotechnology
In principle:
Genetics taught for 50 years [Nobel Prize ]
What inferences can be made about heredity from crosses
?
without
knowledge of hereditary molecule or its structure
'Elementen' follow Mendelian Laws
No chromosomes, no chemical basis
Molecular Biology arises with recognition of DNA
structure & function
& elucidation of molecular
mechanisms
"Forward"
vs "Reverse" genetics
Biotechnology applies
mechanisms to manipulate Genes
to produce "Goods & Services"
Bioinformatics applies
computational science
to extract information from large
data sets
Two
candidates: protein versus nucleic acid
Cells contain H20,
lipids, carbohydrates, and
...
(1838) - Discovery of protein
Abundant,
water-soluble, nitrogenous
Hydrolysis of protein 
amino
acids (~20
kinds)
(1868) -
Discovery of nucleic acid [nuclein]
Found in cell nucleus, acidic, rich
in PO4,
Lacks
S (characteristic of protein)
(1910) - Tetranucleotide hypothesis
nucleic
acid repetitive
polymer of four bases
in approximate ratio 1:1:1:1
Structure too simple to carry information
(1928) - transforming principle
Killed
virulent viruses 'transform' live avirulent
viruses (HOMEWORK):
avirulent
viruses become virulent,
Transformation is inherited
Hereditary makeup of organisms can be altered
,
, &
(1944) -
Chemical characterization of 'transforming principle'
Transformation
survives protease treatment,
destroyed
by nuclease
treatment (HOMEWORK)
It's
chemically pure deoxyribonucleic acid (DNA)
& (1952) - 'Blender Experiment'
Bacteriophage grown in
radioactive medium
Proteins labeled with
35S
DNA
labeled with 32P
When bacteriophage infect E. coli,
32P
goes in, 35S stays out
DNA
is transforming principle
&
DNA structure (1953)
(1945) "What is Life?":
Are
there "Other laws of physics?"
, , & ' X-ray crystallography
DNA is a helix:
two or three strands? Bases inside or
outside?
: Chargaff's Rules: Bases occur
in specific ratios
[A] = [T] &
[C] = [G] (Table)
Model building:
Two strands, bases inside
Key recognition :
The
Watson -
Crick "Double Helix" structure for DNA [
1962, w/ ]
double-stranded helix
Two sugar-phosphate backbones
outside
Nitrogenous
bases inside
H-bonds hold
strands held together
Molecular Biology
replaces Genetics
[Nobel Prizes in & ]
Bacteriophage
Genetics
[Nobel
1969]
"Cracking"
the Genetic Code
[Nobel
]
Transposable elements - "Jumping
Genes"
[]
Intron / Exon "split gene"
structure
[ ]
Genetic
Engineering: laboratory
manipulation of DNA
What does a particular region
of DNA do?
Isolation & manipulation of recombinant
DNA []
in vivo / in vitro "cloning" of genes
[]
analysis
& expression of
cloned genes
Restriction
enzymes
[]
DNA
sequencing
[ ]
Automated DNA sequencing
HuGO: the
"Next Generation Sequencing"
(NGS)
Polymerase Chain Reaction (PCR)
[]
qPCR - quantitative PCR
Biotechnology
- "The use of biological systems to produce
goods & services"
Genetically
Modified Organisms ()
:
bovine-sourced insulin replaced by cloned human
insulin (1983)
: first GMO food, engineered for longer
shelf line (1994)
: beta-carotene enhanced rice
cures Vitamin A deficiency (2004)
"genetic scissors"
[
2020]
Therapy for Sickle-Cell Anemia
Resurrecting ancient DNA
(aDNA)
[]
mRNA vaccine
for COVID-19
[
2023]
DNA Forensics
Environmental DNA
(eDNA)
et sequelae
For
further reading:
HF Judson (1996). The Eighth Day of Creation (25th
Anniversary Ed). Simon &
Schuster.
[A general history of molecular biology.
See especially material on the context of ].
JD Watson (2003). . Knopf
[A narrative history of genetics & molecular
biology in the 20th century,
written for the 50th anniversary of the
discovery of the DNA structure].
JD Watson (2012) The
Annotated and Illustrated Double Helix. Simon &
Schuster].
S
Mukherjee (2016). The Gene: An Intimate History.
Scribner
[An extension of
Judson into the 21st Century].
[A discussion of
's theory of with respect to life sciences].
[The
transformation of molecular biology from individual labs
to Big Science].
All text material © 2025 by Steven M. Carr