What are Mutations? Why and How are they Studies?

A mutation is a change in DNA  Mutations are common  Most mutations have no effect  Most mutations in animals are in somatic cells, not the germline.  Mutations with an effect are most likely to be harmful to the organism (~%70).  Most mutations change a single base.  Beneficial mutations drive evolution. Mutations

Types of Mutations  Single nucleotide changes are most common.  DNA of any length can be deleted, inserted, replaced or inverted.  Deletions and insertions can cause shift of reading frames.  DNA can be translocated (moved) between chromosomes, or even organisms. Mutations

Substitution CGGATAACC T GCCTATTGG A CGGATCACCT GCCTAGTGGA CGGATAACC T GCCTATTGG A CGGATACCT GCCTATGGA Deletion THE FAT CAT SAT HEF ATC ATS AT... Frameshift (analogy) Translocation DeletionInversion Mutations

Somatic Mutation Mutations that occur in cells of the body, in organisms that sexually reproduce, these traits are not passed on to offspring. Mutations

Germline Mutation Photo credit: Son Yong Karst, et al.

Most DNA Damage is Repaired Mutations

Why Study Mutations? What are your ideas? Mutations

Why Study Mutations?  To better understand normal functioning.  To learn about genetic disorders.  To understand genetic differences. DAVID SCHARF/SCIENCE PHOTO LIBRARY Fruit fly Drosophila melanogaster with legs where antennas should be. OAK RIDGE NATIONAL LABORATORY/US DEPARTMENT OF ENERGY/SCIENCE PHOTO LIBRARY Mouse iwh obesity mutation, compared to normal lab mouse. Dr Frank Gaillard/ a.org/cases/huntington-s- disease Mutations

What are model organisms? Have you ever heard this phrase? What does it make you think of? What do you think model organisms are in science? Model Organisms

Organisms used in science when human studies are impossible, unethical or impractical are referred to as “model organisms.” You will be asked to answer this question: What is to be gained by learning about an organism you could easily go your whole life without seeing? Give it some thought! Model Organisms

Caenorhabditis elegans is a nearly microscopic nematode (also known as roundworms) that is widely used for experimentation in genetics, developmental biology, cell biology and related fields. Model Organisms

Why use C. elegans for Science ? Like humans, multicellular, eukaryotic, reproduces sexually. Rapid life cycle for genetic and developmental studies. Small number of cells allows detailed study of development. Small genome simplifies linking genes to phenotypes. Small size means many individuals can be observed, and they use little food, space or other resources. Hardy, prolific, easy to keep alive. Adapted from Wormbook Model Organisms