Download DNA`s Discovery and Structure

The Secret Code of Life
Codes and Ciphers:
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The Pigpen code - knows the key
Codes were made as :
a means of sending information
easily such as the Morse code,
or to send secret information – short
and secret
A code replaces words, phrases or
sentences with numbers or letters
while a cipher rearranges the letters
to further disguise the message
Can you decipher this? Can you decode
this message?
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There are no secrets better
kept than the secrets that
everybody guesses."
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This is the pigpen cipher, an
original French cipher, that was
used by groups such as
Napolean’s spies to send secret
messages
Why does the human body need a
code?
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The nucleus has an amazing
design of sending information
quickly to the rest of the cell
(function is to control the cells
functions)
The stored information in the
DNA needs to transfer it’s
information quickly and reliably
into a product.
The information is stored in
packets or “files” called genes.
Genes are places or locations on
a chromosome that contain a
specific piece of information for
the creation of a protein. The
transfer of this information is
called PROTEIN SYNTHESIS.
The Central Dogma
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The central dogma or “idea” of the
transmission of information in the cell is
Transcription Translation
 DNA  RNA  PROTEIN
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Where, DNA is read and transfers the
information of the blueprint of the protein
to RNA, and RNA transfers this
information to be created in the
cytoplasm
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Transcription + Translation = Protein
Synthesis
The Genetic Code
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The DNA has a triplet code using only the 4 nucleotides, A,C,G and
T. Only 3 nucleotides form a triplet which, when in a gene, codes for
a part of a protein.
There are 34 total different triplets that can be created but only 20
different amino acids. (Would a doublet code work just as well?? i.e.
only 2 nucleotides to represent 20 amino acids. Why are there a lot
of codes that mean the same amino acid?)
Many triplets in a specific order will generate a specific protein (this
is based on the order of the bases in the DNA)
The bottom line is that the genes we have in our DNA create
PROTEINS which we need.
These proteins are made up of amino acids joined together in a
specific manner to create the protein needed.
There are 3 stop codons which tell the machinery not to continue the
protein synthesis process.
Example
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TAC GCT TAA CGG ACT TTA
ATG CGA ATT GCC TGA AAT
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AUG CGA AUU GCC UGA
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Met – Arg – Ile – Ala – stop
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DNA STRANDS
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mRNA
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Protein
MUTATIONS – When the code is
changed!
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A mutation is a change in the DNA from its
original form (mutatio = change, alteration in
Latin)
When just one base is changed in the DNA, it
is considered a mutation. It would also create
a new allele for the gene. Not all mutations
are harmful.
Types of Mutations
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i) Insertion: 1 or 2 bases are added
to DNA at one place (not in
multiples of 3 – why is that?)
i)TAC GCT AGG ATG
TAC GGC TAG GAT G
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ii) Deletion: 1 or 2 bases are added
to DNA at one place (not in
multiples of 3 – why is that?)
ii) TAC GCT AGG ATG
TAC CTA GGA TG
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Iii) Substitution: of 1 base for
another base e.g. A  T or G  C
iii)TAC GCT AGG ATG
TAC ACT AGG ATG
Effects of mutations on Proteins
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Positive – causes the protein
to be have an even better
function
Negative – causes the
protein to have little or no
function OR disrupts another
protein’s function e.g. Sickle
cell anemia
Neutral – causes the protein
to have no significant change
in function
Effects of DNA changes on Proteins
A. Normal protein
B. Neutral mutation
No change in
the active site
C. Negative mutation
No
active
sites
D. Positive mutation
2 active sites
now, more
effective
protein