Part 3: Expression and Regulation of Genetic Information
The Genetic Code and Transcription
is composed of triplets
that make up
, each of which specifies one amino acid.
The triplet nature of the code was first revealed by
The genetic code was first cracked by using artificial
translation system to synthesize
were used to discover the base composition of more
was used to determine other specific codon assignments.
were used to complete the construction of the genetic code.
, and exhibits
at the third codon position.
The genetic code is nearly universal, with minor
such as those found in
In some viruses, different initiation points lead to
Studies with bacteriophage
provided initial evidence that
serves as the intermediate molecule between DNA and proteins.
Transcription begins with template binding by
at an site upstream to the gene called the
Eukaryotes possess three forms of
each of which transcribes different types of genes.
The initial transcript in eukaryotes is a
that must be
by splicing together the
to produce the mature
Introns are removed by splicing together the
and II) or by
The size of the mature
is usually much smaller than that of the initial RNA
can now be
using electron microscopy.
Nov 11, 2008