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8.7 Mutations SPONGE 6 What do you think of when you hear the word “mutation”? –Are they always bad? –Give me an example.

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Presentation on theme: "8.7 Mutations SPONGE 6 What do you think of when you hear the word “mutation”? –Are they always bad? –Give me an example."— Presentation transcript:

1 8.7 Mutations SPONGE 6 What do you think of when you hear the word “mutation”? –Are they always bad? –Give me an example

2 8.7 Mutations Mutations?

3 8.7 Mutations Not all mutations are bad Most do have negative effects

4 8.7 Mutations KEY CONCEPT Mutations are changes in DNA that may or may not affect phenotype.

5 8.7 Mutations A mutation is a change in an organism’s DNA. Many kinds of mutations can occur, especially during replication.

6 8.7 Mutations GENE MUTATIONS 1)A point mutation substitutes one nucleotide for another. GAT CTC GAT CAC mutated base

7 8.7 Mutations Example of a point mutation Sickle cell anemia

8 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….

9 8.7 Mutations Example of a frame shift mutation: Tay–Sachs disease around 6 months of age –Nerves start deteriorating –Child becomes blind, deaf, and unable to swallow –Death usually occurs before the 4 th year

10 8.7 Mutations Chromosomal mutations –affect many genes. –may occur during crossing over

11 8.7 Mutations 1) Gene duplication results from unequal crossing over.

12 8.7 Mutations 2) Translocation results from the exchange of DNA segments between nonhomologous chromosomes.

13 8.7 Mutations Mutations may or may not affect phenotype (looks). Chromosomal mutations tend to have a big effect. Some gene mutations change phenotype. –may cause a premature stop codon. –may change protein shape or the activation site. –may change gene regulation. Ex: down syndrome

14 8.7 Mutations Some gene mutations do not affect phenotype. –A mutation may be silent. –A mutation may occur in a noncoding region. –A mutation may not affect protein folding or the active site. blockage no blockage Ex: Cystic Fibrosis- caused by a deletion

15 8.7 Mutations Mutations in body cells do not affect offspring. Mutations in sex cells can be harmful or beneficial to offspring. Natural selection often removes mutant alleles from a population

16 8.7 Mutations Beneficial mutations CCR5 32 is a deletion thought to resist the bubonic and pneumonic plague as well as HIV Mutations that cause resistance to antibiotics

17 8.7 Mutations 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. Conjoined Twins

18 8.7 Mutations Mutations caused by Mutagens Radiation


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