Mutations

What is a mutation? Changes in the DNA sequence that affect genetic information.

Gene Mutations Result from changes in a single gene. 3 Types: Substitution Insertion (Frame-shift) Deletion (Frame-shift)

Point Mutations Substitution One nucleotide replaces another. Usually changes one amino acid in the sequence of the protein. Ex: sickle cell anemia

Point Mutation (Substitution)

Frame Shift Mutations Insertion/Deletion Insertion - the addition of a nucleotide. Deletion - the removal of a nucleotide. Bases are still read in groups of three (codons). Changes many amino acids in the sequence of the protein

Frame Shift Mutation (Insertion)

Frame Shift Mutation (Deletion)

Which would you rather have?

What Causes Mutations? May occur spontaneously during cell division/meiosis. X-rays Asbestos Insecticides UV light Radioactive substances

How Are Mutations Passed On? The mutation must happen in a sex cell (gamete).

Chromosomal Mutations Involve changes in whole chromosomes. chromosomal mutations 5 types: 1. Translocation 2. Duplication 3. Deletion 4. Inversion 5. Nondisjunction

Chromosomal Mutations Deletion, Inversion, Translocation, Duplication https://www.youtube.com/watch?v=FgMKGIED4Yo

Chromosomal Mutations https://www.youtube.com/watch?v=FgMKGIED4Yo

Nondisjunction An error that occurs during meiosis in which homologous chromosomes fail to separate properly. One gamete may receive two of the same type of chromosome and another gamete receives no copy. Ex- down syndrome

Down Syndrome (Trisomy 21) Trisomy: having three copies of one chromosome. Down Syndrome is caused by a trisomy on the 21st chromosome. Likelihood of this disorder increases with the increasing age of the mother.

Age of Mother vs. Down Syndrome

Ways to Detect Genetic Disorders Karyotyping- prepared enlarged photograph showing paired homologous chromosomes from a cell. May show chromosomal abnormalities such as an extra or missing chromosome.

Testing for Down Syndrome https://www.youtube.com/watch?v=Ju-q4OnBtNU http://www.bmhvt.org/healthmatters/pros-and-cons-of-genetic-screening-during-pregnancy What are your thoughts on Down Syndrome testing? Would could the mother do?

Medical Genetic Research Generates knowledge used to design ways of diagnosing, preventing, treating, controlling, or curing diseases of plants and animals.

Genetic Counseling Discussions between physician and the family which may include inheritance patterns, prediction of genetic disorders, and family planning. Screening Karyotyping Amniocentesis

Screening Chemical analysis of body fluids such as blood and urine. Analysis may indicate the presence of chemicals associated with genetically-related disorders.

Amniocentesis Involves the removal of amniotic fluid for chemical analysis. This technique can show the chromosome content of the cells of the embryo.

Amniocentesis https://www.youtube.com/watch?v=bZcGpjyOXt0

Genetic Disorders PKU (Phenylketonuria): individuals lack the enzyme that is needed to break down phenylalanine. If a newborn has PKU, phenylalanine may build up in the tissues during the child’s first years of life and cause severe mental retardation. https://www.youtube.com/watch?v=XKSoMi4U-1k

Genetic Disorders: PKU

Genetic Disorders Tay-Sachs Disease: lipid accumulation in the brain cells, mental deficiency, blindness, death in early childhood. https://www.youtube.com/watch?v=RzEpkBU-ITA