Transcript Topic: Genetic Mutations

Topic: Genetic Changes
Aim: How can genetic information
be altered?
Thought Questions
• How is reading the DNA like a recipe?
• What happens when recipes go wrong?
• How does a wrong recipe relate to having
the wrong “DNA” recipe?
What is a mutation?
• A genetic change/alteration that occurs on or
within DNA.
• Results in a different transcription and
translation message ultimately a different
protein
– Consequences: the protein may be the wrong protein
that the cell needs
• Passed on through sex cells ONLY, not somatic cells
• Mutations can be harmful when expressed, but can be
hidden
Agents that Cause Mutations:
• Environment
– Mutagens: factors in the environment that can
cause a mutation
– Long term radiation exposure ( UV from the sun,
radioactivity) cancer related
– Chemical exposure ( formaldehyde, benzene, cigarette
smoke)
– pH, physical manipulation, temp Example: Temp.
influenced : Himalyan Rabbit expresses genes in the
winter( low temps) to make black fur for warmth.
*** Environment can
influence genetic expression
Temperature Influences Trait
Rabbit expresses genes for a dark coat on particular parts of its body.
When an ice pack is placed on its back, it too turns black
WHY DID THIS HAPPEN?
Types of Mutations
A- Chromosomal Mutations: changes that
occur on sections of the chromosome or
the complete chromosome structure.
Ex: Inversion and Translocation
B- Gene (Point) Mutations: changes that
occur on individual base(s) of the
nucleotides
Ex: Substitution, Addition, Deletion, Point
Inversions
Types of Chromosomal
Mutations- Inversion
• Segment of the chromosome breaks off
and reinserted in the same place but in the
reverse direction relative to the rest of the
chromosome
Types of Chromosomal
Mutations- Translocation
Information from one of two homologous
chromosomes breaks and binds to the
other. Known as “jumping genes”
Gene Mutations- Substitution
Substitution (point) mutation = when
one base is replaced with another
Results in transcription and translation
of a different amino acid than expected.
Sickle Cell Anemia  disease where
substitution occurs on one base
Sickle Cell Anemia
• Disease where an individuals red blood
cells are sickle in shape due to a
substitution mutation that occurs in the
DNA sequence of their red blood cell.
Valine is substituted for glutamic acid
Results of sickle cell anemia
Gene Mutation- Addition
• Addition (point) mutation = when bases
are added to the DNA sequence
• Results in the frame shift (bases move
down) from the nucleotide sequences.
Different (sometimes wrong or unwanted)
amino acids are created into proteins
Gene Mutations- Deletion
• Deletion= nucleotides are deleted, which
affects the coding of proteins that use this
DNA sequence
Results of Addition & Deletion
Mutations
Addition and Deletion mutations cause the
DNA sequence to be read incorrectly
Frameshift Mutation
RESULTS OF ALL TYPES OF
MUTATIONS
• Overexpression of protein instruction
• No expression of protein instruction
• Expression of wrong protein instruction
Human Diseases Caused By
Mutations
1) Sickle Cell Anemia - substitution
mutation
2) Huntington’s Disease - addition
mutation
3) Tay-Sachs Disease - deletion
mutation
4) PKU- phenylketonuriachromosomal mutation
PKU-phenylketonuria
• Missing enzyme that helps to breakdown
phenylalanine. Genes are not expresses
to make the enzyme phenylalanine
hydroxylase
Recipe for a Ham & Cheese
Sandwich (Normal)
1) Take 2 pieces of ham and place it on one slice
of bread.
2) Add one slice of cheese on top of the ham.
3) Place one piece of lettuce on top of the
cheese.
4) Place mayo on the second piece of bread.
5) Close the sandwich with the mayo on the
inside.
Enjoy!
Name the mutation
1) Takke 2 pieces of hham and place it on one
slice of bread.
2) Add one sliccce of cheese on top of the ham.
3) Ppplace one piece of leettuce on top of the
cheese.
4) Place mayyyo on the seccond pieeece of
bread.
5) Clossse the sandwich with the mayo on the
inside.
Enjoyyyyyyy!
Name the mutation
1) Place mayo on the.
2) Take 2 pieces of ham and on top of the ham.
place it on one slice of bread.
3) Add one slice of cheese
4) Place one piece of lettuce on top of the
cheese.
5) second piece of bread Close the sandwich with
the mayo on the inside.
Enjoy!
Name the mutation
1) Take 2 pieces of ham and place it on one slice
of bread.
2) Place mayo on the second piece of bread.
3) Close the sandwich with the mayo on the
inside.
Enjoy!