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