Mutations – random Replication errors Don’t necessarily lead to harm, but some do Permanent change in sequence – If in gamates (sex cells), passed to offspring Occur 1/100,000 base pairs With proofreading, 1/billion base pairs Caused by environmental factors – Most fixed, but some not – Smoking, UV radiation

1. Substitution Change in a single base in a DNA sequence A point mutation

Point mutation example Sickle cell anemia – changes hemoglobin protein – Sickle shape – Doesn’t carry oxygen well – Clogs capillaries – On chromosome 11 – Inherited disorder

Point Mutation

Ex. Point mutation - substitution Fatal Familial Insomnia Point Mutation Dominant inherited disease Can’t sleep so die 10 minute Jon Stossel clip on FFI

2. Frameshift mutations Change in nucleotide sequence that causes each nucleotide to slide down one position Significantly changes amino acid sequence.

3. Insertion Adding a nucleotide – Shifts entire frame Can be one nucleotide or larger segments A

Gene vs. Chromosomal Mutation Gene Changes DNA sequence of short segment of DNA that encodes for specific protein Chromosomal Mutation Changes the number or structure of entire chromosomes

4. Deletion Single nucleotide or fragment breaks off Lost when cell divides New cell lacks this set of genes - 70% of all cystic fibrosis caused by deletion

Cystic fibrosis - info A defective gene and its protein product – body produces unusually thick, sticky mucus – clogs the lungs – leads to life-threatening lung infections Also obstructs the pancreas – stops natural enzymes from helping the body break down and absorb food. YouTube - What is Cystic Fibrosis?

Life with CF No cure for CF – treatments include: dietary enzymes supplements various methods medications, such as antibiotics and inhaled steroids, to clear the airway and improve lung function Average life span: 37 years

Video Point and frameshift mutations Point (substitution) and Frameshift insertion and deletions) mutations Point (substitution) and Frameshift insertion and deletions) mutations

5. duplication Extra copy of gene sequence on same chromosmome Huntington’s – Degenerative brain disorder – Symptoms appear years – Lose ability to walk, think, talk, reason 6. inversion Fragment reattaches in reverse order hemophilia

7. translocation Fragment of chromosome join different chromosome YouTube - Translocation

Video of Mutations video on types of mutations

Silent Mutations Changes in nucleotide sequence that does not effect the protein’s function – Does not change the amino acid sequence – May occur in “non-coding” region of DNA, introns

Beneficial mutations mutations may have a positive effects. a specific 32 base pair deletion in human may give some HIV resistance and delays AIDS onset more common in those of European descent. Maybe because… European population conferred resistance to the bubonic plague in mid-14th century Europe. People who had this mutation were able to survive infection; thus, its frequency in the population increased. It could also explain why this mutation is not found in Africa where the bubonic plague never reached.bubonic plague New theory states smallpox

More positives of mutations Mutations provide the necessary genetic variation for species to be able to change over time EVOLUTION

Harmful mutations Changes in DNA caused by mutation can cause errors in amino acid sequence, creating partially or completely non-functional proteins. Can be detrimental to organism.