Mutations

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Mutations
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• A mutation is a mistake in the cells DNA.
• GTTACG ? GGTACG

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• DNA contains the information on how to make
  proteins.
• Codons of the mRNA will code for a specific amino
  acid.

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• The order and length of the amino acid chain
  determine how it is folded and shaped.
• If any of the amino acids are changed or the
  length is changed, the shape is different.
• The proteins function may change or not work at
  all.

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• Mutations are only passed on to your offspring if
  they occur in your gametes (egg or sperm)
• Mutations that occur in your body cells may cause
  cancer.

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Types of Mutations

• Substitution
• (point mutation change in one nucleotide)

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Examples

• Cystic fibrosis
• Sickle Cell Disease
• GAG glu
• GTG val
• One amino acid in the protein hemoglobin changes
  the shape of the cell

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Silent Mutation
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Insertion

• This causes a frameshift mutation. All the
  previous codons are now changed into different
  codons and therefore, different amino acids.
• (also known as missense mutation)

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• Multiple insertions.
• A gene may be duplicated.

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Deletion

• A nitrogen base is deleted and a frameshift
  mutation occurs.

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• A gene may be deleted.

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Inversion

• The order of nitrogen bases can be switched
  around. A few amino acids may change.
• Genes may switch places. May not be expressed
  properly.

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What causes mutations?

• Induced mutations Toxic chemicals and radiation

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Examples of plants that were produced via mutation breeding are given in the table below.
Crop Cultivar Name Method Used to Induce Mutation
rice Calrose 76 gamma rays
wheat Above sodium azide
wheat Lewis thermal neutrons
oats Alamo-X X-rays
grapefruit Rio Red thermal neutrons
grapefruit Star Ruby thermal neutrons
burmuda grass Tifeagle gamma rays
burmuda grass Tifgreen II gamma rays
burmuda grass Tift 94 gamma rays
burmuda grass Tifway II gamma rays
lettuce Ice Cube ethyl methanesulphonate
lettuce Mini-Green ethyl methanesulphonate
common bean Seafarer X-rays
common bean Seaway X-rays
lilac Prairie Petite thermal neutrons
St. Augustine grass TXSA 8202 gamma rays
St. Augustine grass TXSA 8212 gamma rays
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Spontaneous mutations

• Mistakes in DNA replication.
• Your DNA contains 3 billion base pairs. These
  are copied every time you make a new skin cell,
  liver cell, stomach cell.
• Enzymes check the DNA to make sure there are no
  mistakes in the copying process.

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• But. No process is 100 accurate.
• About one in every 50 million nucleotides has a
  mutation occur.
• This means every new cell contains about 120 new
  mutations!

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Worried?

• Dont be
• As much as 97 of your DNA doesnt code for
  proteins.
• We dont know what this DNA is for.
• Also, Silent Mutations occur which dont change
  the protein.

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Are all mutations bad?

• No, some are good.
• Antibiotic resistance in bacteria
• Sickle cell resistance to Malaria

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• Resistance to artherosclerosis
• Immunity to HIV
• Lactose tolerance

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Blue Skin (diaphorase deficiency)
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Werewolf syndrome (congenital generalized
hypertrichosis)