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 TT T A = valine G U A = asparagine A A U

Read from this side first! Read from the top second. Then read from this side third.

2A. Point Mutations Substitution –O–One nitrogenous base is replaced with a different one – CTAGGA – GAUC A U GAU = ? / CAU = ? / CCU = ? –A–Aspartate / Histidine / Proline

2B. Frameshift Mutations Insertion –O–One or more bases are added to a gene – TAGCCT – A G UCGGA AGU = ? / AUC = ? / CGG = ? –S–Serine / Isoleucine / Arginine

2B. Frameshift Mutations Deletion –O–One or more bases are deleted from a gene – CGATAG – _– __CUAUC GCU = ? / AUC = ? –A–Alanine / Isoleucine CUA = ? / UC = ? –L–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 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 disease Recessive Causes infants’ nervous systems to break down –Death in early childhood

Cystic Fibrosis Recessive Causes for the overproduction of mucus Mucus clogs organs, especially lungs making breathing difficult

Hemophilia Sex-linked recessive Blood clotting disorder

Huntington’s disease Dominant Causes brain to gradually deteriorate Usually goes unnoticed until adulthood