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Genetic Mutations
Unit 2-2 Notes
Mr. Hefti – Pulaski Biology
1. Genetic Mutations
“a change in the DNA of a gene”
–Mutations in gametes can be passed on to offspring
–Mutations in body cells affect only the individual in which they occur
2. Categories
• Point Mutations– Change in one or just a few bases in a gene
• Frameshift Mutations– Cause genes to be read in the wrong three-
nucleotide sequence
Three nucleotide sequences are called “codons”
See if you can find the amino acid that these DNA sequences code for using the Universal Codon Chart…
New rule: when referring to the amino acids that DNA codes for, T still goes with A, but now A goes to U (which stands for Uracil).
C A T T T A
= valineG U A = asparagineA A U
Read from this side first!
Read from the top second.
Then read from this side third.
2A. Point Mutations• Substitution
– One nitrogenous base is replaced with a different one
– C T A G G A – G A U C A U
• GAU = ? / CAU = ? / CCU = ?–Aspartate / Histidine / Proline
2B. Frameshift Mutations• Insertion
– One or more bases are added to a gene
– T A G C C T
– A G U C G G A• AGU = ? / AUC = ? / CGG = ?
–Serine / Isoleucine / Arginine
2B. Frameshift Mutations• Deletion
– One or more bases are deleted from a gene
– C G A T A G– __C U A U C
• GCU = ? / AUC = ?–Alanine / Isoleucine
• CUA = ? / UC = ?–Leucine / “Nothing”
3. Sources of Mutations
• X-rays• UV rays• Radiation• Asbestos• Alcohol• LSD• Marijuana• Benzene• Formaldehyde
4. Genetic Diseases
• Some genetic diseases are caused by inherited mutations
– Sickle cell anemia– Tay-Sach’s disease– Cystic fibrosis– Hemophilia– Huntington’s disease
Sickle cell anemiaSickle cell anemia
• Recessive
• Causes for the abnormal development of rbc’s
• Sickle shape causes cells to break apart or get jammed in blood vessels
Tay-Sach’s diseaseTay-Sach’s disease
• Recessive
• Causes infants’ nervous systems to break down– Death in early childhood
Cystic FibrosisCystic Fibrosis
• Recessive
• Causes for the overproduction of mucus
• Mucus clogs organs, especially lungs making breathing difficult
HemophiliaHemophilia
• Sex-linked recessive
• Blood clotting disorder
Huntington’s diseaseHuntington’s disease
• Dominant
• Causes brain to gradually deteriorate
• Usually goes unnoticed until adulthood
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