Mutations

1
Mutations

• HW
• Read p188-200

2
Change

• Last class we looked at mRNA translation. You
  saw how difficult it can be to translate codons
  into their amino acid counterparts.
• A mutation is a random change in the sequence of
  nucleotides in DNA.
• Some mutations are lethal, some are not. It
  depends on the affected genes and the number of
  mutations.
• Mutations are not all bad. Variation is a result
  of mutations and can actually improve a
  populations survivability. (Darwin Survival
  of the Fittest?)

3
Types of mutation

• Deletion This occurs when a piece of the
  chromosome breaks off and is lost.
• Duplication A section of chromosome joins into a
  homologous chromosome already containing the same
  section.
• Translocation A section of chromosome joins to a
  different chromosome.

4
Other forms

• Did you notice the previous slide focused on
  sections of chromosomes mutating?
• How about individual nucleotides?
• Think about our translation activity from last
  class. What happens if you misread codons or
  skip a few?

5
More mutations

• Frameshift mutation A deletion or addition of
  nucleotides that disrupts codons. If the
  addition/deletion is 3 bases long, the rest of
  the sequence could continue normally.

6
More mutations

• Point mutation A change in a single base-pair.
  This is the least disruptive form of mutation
  because 30 of the time it doesnt even affect
  the codon.

7
Cancer

• Some mutations cause changes in cell growth or
  specialization.
• When a cell has uncontrolled or abnormal growth,
  it is considered cancerous.
• Oncogenes are genes that cause cells to become
  cancerous.

8
Oncogene Causes

• There are 3 possible ways to mutate a gene into
  an oncogene
• Nucleotide mutation that creates a more-potent
  form of a protein
• Duplication mutation that creates multiple copies
  of a protein
• Translocation mutation that moves behind a
  promoting gene, causing greater output.

9
Environmental factors

• Weve all heard things like smoking causes
  cancer but what does that mean?
• Mutagens are environmental factors that can
  affect DNA. Some examples are
• Radiation
• Carcinogens (tars in cigarettes, drugs, hair
  dyes)
• UV radiation

10
Group Presentations

• Research the following
• Symptoms/Signs
• What gene(s) are affected?
• How often does it occur?
• Fatal?
• Well-known cases/ History
• Other facts?
• Pictures/Diagrams