Chapter
17
Animations
Art
Unit 3: Genetics
From Gene to Protein
Review
A major function of DNA is to direct the synthesis of
in two
steps:
and
; this flow of information is known as the central
.
In
prokaryotes,
transcription and translation take place
. In eukaryotes, an intermediate
step
of RNA
is needed due to the presence of the
.
Transcription
has three stages:
Initiation
occurs at the
promoter
sequence on the DNA.
Elongation
is performed by RNA
.
Termination
In eukaryotes, the transcript is a
and needs to be processed before it can be used in translation.
The 5
'
end receives a modified nucleotide
, and the 3
'
end gets a
tail.
are removed from the
pre-mRNA
and its
are
spliced
together by
.
The mature mRNA exits the nucleus, and translation takes
place
on
, together with
RNA (tRNA).
The genetic information on mRNA is encoded as a sequence of RNA
triplets,
or
. The
possible codons constitute the genetic
code.
The
on the
transfer
RNA (
tRNA
) binds with the mRNA
to add a specific amino acid to the polypeptide chain.
Translation
also has three stages:
Initiation
occurs when the ribosome reads a
codon.
Elongation
produces a
by the formation of
bonds between amino acids.
Termination
occurs when the ribosome reads a
codon.
Central dogma
summary.
are changes in the DNA of a cell which may lead to an abnormal
. Point
mutations
are changes in one pair of nucleotides.
A base-pair
mutation may result in a
mutation,
a
mutation,
or a
mutation.
Insertions and
of nucleotide pairs may produce
mutations.
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