Genetic
Code
Genetic
Code -
A
recapitulation
of
the
relationship
between
genes
and
proteins
is
desirable
for
an
understanding
of
the
genetic
code.
1.
All
metabolic
reactions
are
catalysed
by
specific
enzymes.
All
enzymes
are
proteins
2.
The
action
of
an
enzyme
depends
upon
the
sequence
of
amino
acids
constituting
it
3.
The
one
gene
one
enzyme
hypothesis
proposed
by
Beadle
and
Tatum
in
1940s
states
that
the
synthesis
of
an
enzyme
is
controlled
by
a
particular
gene
4.
The
gene;
which
is
almost
always
a
segment
of
a
DNA
strand,
transcribes
an
mRNA
strand,
which
in
turn
translates
a
polypeptide
chain.
5)
Messenger
RNA
thus
acts
as
an
intermediate
in
conveying
information
from
the
sequence
of
nucleotides
in
DNA
to
the
sequence
of
amino
acids
in
the
polypeptide
chain
(Sequence
Hypothesis)
6.
Each
amino
acid
is
specified
by
a
sequence
of
three
bases
(the
codon)
on
mRNA
7.
Each
tRNA
molecule
has
a
sequence
of
three
bases
(the
anticodon)
which
reads
a
codon
of
mRNA.
Transfer
RNA
molecules
thus
serve
as
adaptors
in
proteins
synthesis
by
reading
mRNA
co
dons
in
a
sequence
(Crick's
Adaptor
Hypothesis)
8.
The
relationship
between
the
sequence
of
bases
in
DNA
|
RNA
and
the
sequence
of
amino
acids
in
a
polypeptide
chain
is
called
the
genetic
code.
The
code
indicates
which
codons
specify
which
amino
acids.
|