2. Milestone in molecular biology
• The molecularization of biology since the middle of the 20th century has
had a huge impact on research as well as on everyday applications. It
consists of a synthesis of many biological, biochemical and medical
disciplines. Whether in the diagnosis of diseases, the production of
detergents, chemical basic materials or foodstuffs, biotechnological
processes determine modern everyday life.
• The advancement of knowledge made possible by the development of
molecular biology has enriched the knowledge about the function of cells
and of the whole organism in a revolutionary manner, and one begins to
understand the complexity and diversity of the regulatory processes at the
molecular level and to recognize the molecular structures involved.
3. 1911-20 TIME OF WAR
• The second decade of 20th century was the time of
great international tension that erupted into a war.
• Many researchers diverted their work from pure
science to war effort
• In 1914 henry hallet dale isolated acetylcholine
involved in sending nerve impulses.
4. In 1915
• Frederick twort english bacteriologist describes
bactriophages
• D herelle identified bacteriophage and coined the
term.
• In worldwide epidemic influenza killed more than
25 million people as a result of world war.
7. Three basic laws of Inheritance
– Theory of Segregation
– Theory of Independent Assortment
– Incomplete Dominance
8. Johann Friedrich Miescher(1869)
• Extraction of DNA. • - At first, Miescher focused on the
various types of proteins that make up the leucocytes
• Miescher noticed that a substance precipitated from the
solution when acid was added and dissolved again when
alkali was added
• He had, for the first time, obtained a crude precipitate of
DNA. Miescher stated that “According to known
histochemical facts, I had to ascribe such material to the
nuclei and he decided to examine the cells’ nuclei more
closely.”
9. Walther Flemming(1882)
• Flemming investigated the process of cell division and
the distribution of chromosomes to the daughter
nuclei, a process he called mitosis from the Greek word
for thread.
• However, he did not see the splitting into identical
halves, the daughter chromatids.
• He studied mitosis both in vivo and in stained
preparations, using as the source of biological material
the fins and gills of salamanders.
10. Boveri-Sutton(1902)
• It correctly explains the mechanism underlying the
laws of Mendelian inheritance by identifying
chromosomes with the paired factors (particles)
required by Mendel's laws.
• It also states that chromosomes are linear
structures with genes located at specific sites called
loci along them.
11. • It states simply that chromosomes, which are seen
in all dividing cells and pass from one generation to
the next, are the basis for all genetic inheritance.
• The demonstration of the chromosomal basis of
inheritance gave rise to the modern science of
genetics.
12.
13. Herman Muller(1927)
• Best known for his successful induction of
mutations of genes in the fruit fly by the use of X
rays. •
• He is known also for his dire warnings concerning
the effects of nuclear radiation on human genes.
19. 3. The purines and pyrimidines were
identified via their ultraviolet absorption
spectra. Chargaff tested the method on
several mixtures of purines and pyrimidines
and reported his encouraging results in the
Classic.
20. • Insights of the composition of DNA with the scientific
community
- Amount of Adenine relative to Guanine differs from one
species to the next.
• - The Amount of Adenine in DNA always equals that of
Thymine and the amount of guanine always equals to
Cytosine. • Thus, • A = T and G = C
21.
22.
23. Francis Crick James Watson(1953)
• Crick determined that DNA was a double helix made of
two polynucleotide strands
• They looked at the photo taken by Rosalind Franklin
closer and found that DNA was a double helix and that
it was made of two polynucleotide strands.
• Crick determined that DNA was a double helix made of
two polynucleotide strands • They looked at the photo
taken by Rosalind Franklin closer and found that DNA
was a double helix and that it was made of two
polynucleotide strands.
24.
25. Marshall Nirenberg(1961)
• The Genetic code was discovered; scientists are
now able to predict characteristics by studying DNA
• This leads to genetic engineering, genetic
counseling.
26.
27. Paul Berg(1972)
• Creates first recombinant DNA molecules.
• He was the first to combine deoxyribonucleic acid
(DNA) molecules from different organisms, creating
a hybrid known as recombinant DNA.
28. He selected the genes of simian virus 40 (SV40), a monkey
virus known to cause cancer in human cells and in laboratory
cultures
First, he combined the DNA molecule of SV40 with the
DNA of a bacterial virus called lambda.
He then planned to insert this hybrid molecule into the
bacterium Escherichia coli, where the lambda virus
would then attack the bacteria.
29. • Berg surmised that when the virus entered the baterial
cell, it would inject its own
DNA-The recombined SV40-lambda molecule. The bacteria
would then multiply, causing the alien gene to replicate
itself in large quantities.
• His genetic-engineering technique is used to manufacture
specific human proteins like interferon, and has created the
potential for curing genetic defects.
30.
31. Goal of HGP
• Through a process known as sequencing, the
Human Genome Project has identified nearly all of
the estimated 20,000 to 25,000 genes (the basic
units of heredity) in the nucleus of a human cell.
• The project has also mapped the location of these
genes on the 23 pairs of human chromosomes, the
structures containing the genes in the cell’s nucleus
