The Secret Code of Life:

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The Secret Code of Life

• The Cellville Cipher

?Genome British Columbia, 2004
www.genomicseducation.ca
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Codes and Ciphers

• The Pigpen code will work to encode secret
  messages only if the other person receiving the
  message 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

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Can you decipher this? Can you decode this
message?

• There are no secrets better kept than the secrets
  that everybody guesses."
• This is the pigpen cipher, an original French
  cipher, that was used by groups such as
  Napoleans spies to send secret messages

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Why does the human body need a code?

• The nucleus has an amazing design of sending
  information quickly to the rest of the cell
  (function is to control the cells functions)
• The nucleus houses the DNA which owns the genetic
  code.
• The stored information in the DNA needs to
  transfer its 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.

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The Central Dogma

• The central dogma or idea of the transmission
  of information in the cell is
• Transcription Translation
• DNA ? RNA ? PROTEIN
• 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
• Transcription Translation Protein Synthesis
• On your worksheets, which represents the RNA?
  Which represents the protein?

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The Genetic Code

• 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.

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Example

• TAC GCT TAA CGG ACT TTA
• ATG CGA ATT GCC TGA AAT
• AUG CGA AUU GCC UGA
• Met Arg Ile Ala stop

• DNA STRANDS
• mRNA
• Protein

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MUTATIONS When the code is changed!

• 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.

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Types of Mutations

• A. Chromosomal Mutations
• Aneuploidy or a loss or gain of a whole
  chromosome occurs when mitosis or meiosis
  doesnt function correctly and causes a cell to
  have 46 /or- 1 or 2 chromosomes e.g. X0
  Turners syndrome
• Polyploidy or a loss or gain of a whole set of
  chromosomes instead of having 46 chromosomes, an
  additional 23 chromosomes are added or 23 are
  lost! (not found in humans but can occur in
  plants!!)
• Loss of a part of an arm of a chromosome
  translocation. This occurs when the arm of one
  chromosome is attached to a different chromosome.
  (Could be reciprocal where both arms are
  attached to the other recipient chromosome)
• Inversions where a portion of a chromosome
  rearranges the order of the DNA inside the arm
• Deletions a large piece of DNA is taken out of
  the chromosome
• Duplication a large segment of DNA is copied and
  inserted beside its original sequence.
• Insertion a large piece of DNA coming from one
  chromosome and put into another

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Types of Mutations

• B. Point Mutations
• i) Insertion 1 or 2 bases are added to DNA at
  one place (not in multiples of 3 why is that?)
• These mutations can cause serious effects if it
  occurs within a gene as the triplet sequence will
  be disrupted
• ii) Deletion 1 or 2 bases are added to DNA at
  one place (not in multiples of 3 why is that?)
• These mutations can cause serious effects as well
  if it occurs within a gene as the triplet
  sequence is disrupted
• Iii) Substitution of 1 base for another base
  e.g. A ? T or G ? C
• These mutations may or may not be harmful
  depending on where the change in the gene occurs
  and the effect of this change on the resulting
  amino acid that it is changed to.

• i)TAC GCT AGG ATG
• TAC GGC TAG GAT G
• ii) TAC GCT AGG ATG
• TAC CTA GGA TG
• iii)TAC GCT AGG ATG
• TAC ACT AGG ATG

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Effects of mutations on Proteins

• Positive causes the protein to be have an even
  better function/ does its job better (this will
  allow for natural selection and evolution)
• Negative causes the protein to have little or
  no function OR disrupts another proteins
  function e.g. Sickle cell anemia
• Neutral causes the protein to have no
  significant change in function (many are in this
  category such that we never see disease from
  these mutations)

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Effects of DNA changes on Proteins
A. Normal protein
B. Neutral mutation
No change in the active site
D. Positive mutation
C. Negative mutation
No active sites
2 active sites now, more effective protein
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Bibliography and Credits

• http//www.nationalarchives.gov.uk/online/spies/co
  demaster/default.asp
• http//www.accessexcellence.org/AB/GG/mutation2.ht
  ml
• http//www.people.virginia.edu/rjh9u/code.html
• http//www.nationalarchives.gov.uk/online/spies/co
  demaster/default.asp
• http//www.accessexcellence.org/AB/GG/dna2.html
• http//www.accessexcellence.org/AB/GG/mRNA.html

?Genome British Columbia, 2004
www.genomicseducation.ca