1. Mutations in DNA

2. Mutations Mutations: changes in the DNA nucleotide sequence
Occurs when:
Errors are made during DNA replication (copying)
Errors are made during transcription
DNA is exposed to mutagens
Source of variation in living things

3. How do mutations affect the cell?
Fact 1: Sequence of DNA codes for the sequence of amino acids
Fact 2: Sequence of amino acids determines the shape of the protein
Fact 3: Shape of a protein determines the proteins functions (capabilities).
Question: What’s the problem with mutations?
Answer: Mutations can create nonfunctioning or malfunctioning proteins

4. thesunwashotbuttheoldmandidnotgethishat
Unit 4, Topics 3 and 4 - Gene Expression and Control of Gene Expression
OBJ 15
thesunwashotbuttheoldmandidnotgethishat
the sun was hot but the old man did not get his hat
the sun was hot but the ol’ man did not get his hat
the sun was hot but the old man did not get his cat
the sun was hot but the old . an did not get his hat
the dsu nwa sho tbu tth eol dma ndi dno tge thi sha t

5. Is mutation a bad word? Sometimes, yes! Many times, no!
Mutations create variation in populations
Variations can give individuals a greater chance for survival (blubber in a whale, fighting off an infection because of a newly shaped immune system protein)
Some mutations are “silent” in that they do not affect protein shape and/or function

6. If I have a mutation in a gene thats important for survival, will I die?
Depends on severity of mutation (how badly it alters the protein)
Remember– we have TWO copies of each gene (one from mom, one from dad).
If one “normal copy” of a gene compensates for a “broken copy”, the mutation is called recessive
If one broken copy is enough to do damage, called a dominant mutation

7. Sickle Cell Point Mutation

9. Sickle vs. normal RBC

10. Phenylketonuria (PKU)
Caused by a recessive mutation in the gene that codes for an enzyme (PAH) that converts phenylalanine, an amino acid, to tyrosine, another amino acid
Build up of phenylalanine byproduct causes mental retardation

11. Albinism
Caused by a recessive mutation in a gene that codes for an enzyme that makes melanin
Melanin gives hair, skin, and eyes pigmentation, so a lack causes paleness
Problems: sunburn, skin cancer, retina damage

14. Tay-Sachs
Recessive mutation in a gene that codes for a protein that prevents lipid build up in brain cells.
Lipid build up destroys brain cells
Death occurs in early childhood
More common in Ashkenazi Jewish populations

15. Cystic Fibrosis (CF) and Huntington Disease (HD)
CF: Recessive mutation that causes damage to the lungs and pancreas
HD: Dominant mutation that causes progressive breakdown of brain cells.
Occurs in middle age.