GENETIC MUTATIONS What is this picture depicting?

What is a Genetic Mutation?  A mutation is a change in the nucleotide sequence of DNA  Bases can be accidentally deleted, added, inverted (flipped), or replaced with different bases  Mutations can occur in the DNA in any of our cells, but only mutations in our sex cells (gametes) will be passed on to our offspring  Amoeba Sisters- Mutations Amoeba Sisters- Mutations

Substitution Mutation One single DNA base is changed Three Types: Silent, Nonsense, and Missense Silent: One DNA base is changed but it does not change the amino acid produced

Nonsense Mutations  Nonsense Mutation  DNA base that is substituted, accidentally codes for a STOP codon

Missense Mutation  Missense Mutation  DNA base that is substituted codes for a different amino acid

Insertion Mutation  One or more bases are inserted into the original DNA base sequence  This is sometimes called a frameshift mutation because it shifts the codon reading frame

Deletion Mutation  One or more bases are deleted  This is also caused a frameshift mutation

What Causes Mutations? 1. Can occur randomly during the process of DNA replication 2. Radiation (ultraviolet rays, x- rays) 3. Chemicals (asbestos, tobacco)

Genetic Disorders  Mutations in DNA can result in many different diseases and disorders  Diseases occur because a gene now codes for an abnormal protein or enzyme  It could cause a wrong amino acid to be produced, and as a result the protein may not fold correctly  If this protein or enzyme is very important for the functioning of our body, serious complications can result

Sickle-Cell Anemia  Recessive Inherited disorder  Red blood cells have an abnormal sickle shape  This shape makes it difficult for them to carry oxygen and causes them to clump together  Caused by a change in a single base of the gene that codes for hemoglobin

Sickle-Cell Anemia

Sickle-Cell Inheritance

Tay-Sachs Disease  Recessive Inherited Disorder  Babies lack the enzyme that breaks down lipids in the brain  Without the enzyme, lipids build up and kill brain cells  Disease is fatal and death occurs when a child is several years old

Cystic Fibrosis  Most common fatal genetic disorder  Caused by a recessive allele on chromosome 7  Causes glands to produce a thick mucus that clogs and damages lungs

Down Syndrome  Also called “trisomy 21” because individuals have an extra chromosome 21  Occurs when chromosomes do not divide correctly during meiosis  Characterized by developmental delay and physical abnormalities

Hemophilia  Blood disorder in which individuals are unable to make a certain blood protein that aids in the clotting process  Disorder is caused for a recessive gene that is carried on the x chromosome  Since males only have one x chromosome, hemophilia typically occurs in males Hemophilia and the Royal Family

Hemophilia in the Royal Family  Females are only carriers  Males are the only affected individuals because they only have one x chromosome  50% of the male offspring created by a female carrier will have the disease

Hemophilia in the Royal Family