The term gene was
first coined by the scientist Johannson in the year
1909. Gene is defined as the unit of recombination, mutation and self
reproduction. Chemically, it is found that genes are made up of DNA.
In the year 1928, Frederick Griffith observed the phenomenon, which is now
called bacterial transformation. In 1944, Avery, Mac Leod
and Mc Carty reported the repetition of bacterial
transformation in vitro only.
Friedrich Miescher, in the year 1871, was the first
person to report the presence of nucleic acids from the nuclei of pus cells.
DNA was noticed for the first time by Feulgen in
the year 1924 with his Fuchsin staining technique.
James Watson and Francis Crick, in the year 1953, were the first to propose
the helical structure of DNA. They were also awarded the Nobel Prize for this
The various forms of DNA are a) A-DNA b) B-DNA c) C-DNA d) D-DNA e) Z-DNA
The two functions of DNA are:
a) Autocatalytic - it forms a duplicate copy of itself
b) Heterocatalytic - it directs the formation of
chemical substances other than itself.
Kornberg was awarded the Nobel Prize for the
discovery of the enzyme DNA polymerase.
Heterogeneous nuclear RNA (hn RNA):
Eukaryotic genes are interrupted by non-coding DNA segments. These
intervening sequences are known as introns.
In these places, the eukaryotic cell transcribes a precursor RNA longer than
the mRNA. This is known as Heterogeneous nuclear RNA (hn
American scientists H. Temin and D. Baltimore
demonstrated the synthesis of DNA and RNA template in RNA tumour