Download 8.7 Mutations - Cloudfront.net

8.5 Translation
•Set up Cornell Notes on
pg. 11
•Topic: 8.7 Mutations
•Essential Question:
1. Explain why a
frameshift mutation
has a greater effect
than do point
mutations.
8.7 Mutations
2.1 Atoms, Ions,
and Molecules
1. Explain why a frameshift mutation
has a greater effect than do point
mutations.
KEY CONCEPT
Mutations are changes in
DNA that may or may not
affect phenotype
8.5 Translation
• P.10
Points to Ponder
Point Mutation
Frameshift Mutation
8.7 Mutations
Points to Ponder (Top of p. 10)
• What do you think of when you
hear the word “mutation”?
–Are they always bad?
–Give me an example
8.7 Mutations
Mutations?
8.7 Mutations
Mutations
(1m13s)
8.7 Mutations
KEY CONCEPT
Mutations are changes in DNA that may or may not
affect phenotype.
8.7 Mutations
• Not all mutations are bad, but
most do have negative
effects
What mutations do you notice here? Why might these be
problematic?
8.7 Mutations
•
A mutation is a change in an organism’s DNA.
– Many kinds of mutations can occur, especially during
replication.
8.7 Mutations
GENE MUTATIONS
1) A point mutation substitutes one nucleotide for
another.
GAT
CTC
GAT
CAC
Draw a picture: middle of p. 10
8.7 Mutations
Example of a point mutation
• Sickle cell anemia
8.7 Mutations
2) A frameshift mutation inserts or deletes a nucleotide in
the DNA sequence.
THE CAT ATE THE RAT
THC ATA TET HER AT….
Draw a picture: bottom of p. 10
8.7 Mutations
• Example of a frame shift mutation:
• Tay–Sachs disease
– Develops @ around 6 months of age
– Nerves start deteriorating
– Child becomes blind, deaf, and unable to swallow
– Death usually occurs before the 4th year
8.7 Mutations
Chromosomal mutations
– affect many genes
– may occur during crossing over
8.7 Mutations
Mutations may or may not affect phenotype (looks).
• Chromosomal mutations tend to have a big effect.
• Some gene mutations change phenotype.
Ex: down
syndrome
8.7 Mutations
• Some gene mutations do not affect phenotype.
– A mutation may be silent.
Ex: Cystic Fibrosis- caused by a
deletion
blockage
no blockage
8.7 Mutations
• Mutations in body cells do not affect offspring.
Ex:
Lung cancer
Skin cancer
8.7 Mutations
• Mutations in sex cells can be harmful or beneficial to
offspring.
• Natural selection often removes mutant alleles from a
population
8.7 Mutations
Beneficial mutations
Mutations that cause resistance to
antibiotics
CCR5
32 is a deletion
thought to resist the
bubonic and pneumonic
plague as well as HIV
8.7 Mutations
Conjoined Twins
•
•
•
•
Chang and Eng Bunker
Born in 1811
Married sisters
Had 21 children between
them
• In modern times, they
could have easily been
separated
• Died on the same day in
1874
• Chang contracted
Pneumonia and died in
his sleep- Eng refused to
be separated from his
dead twin and died
several hours later.
8.7 Mutations
Mutations caused by Mutagens
• Radiation
8.7 Mutations
Mutations 2
(5m37s)