Transcript Mutations and gene regulation
Mutations and gene regulation lecture 12-4, 12-5 What are Mutations? Changes in the genetic material. 12-4 Mutations Copyright Pearson Prentice Hall Kinds of Mutations • Substitutions usually affect no more than a single amino acid. Copyright Pearson Prentice Hall Insertion • An extra base is inserted into a base sequence. Copyright Pearson Prentice Hall Deletion • A single base is deleted and the reading frame is shifted. Copyright Pearson Prentice Hall Chromosome Mutations: changes to the whole chromosome • Deletions Copyright Pearson Prentice Hall • Inversions reverse the direction of parts of chromosomes. Copyright Pearson Prentice Hall • Translocations : part of one chromosome breaks off and attaches to another. Copyright Pearson Prentice Hall Significance • Many mutations are neutral. • Some can cause genetic diseases. • Some can be helpful, like resistance to HIV, or polyploidy in plants. How does DNA make different cells? • All cells have a full set of DNA • Not all the DNA is expressed in each one • Promoters and repressors allow only certain genes to be expressed (make protein) Nerve, cardiac, muscle, white blood cells Gene expression • Cells turn their genes on and off as needed. • Repressor proteins stop expression of a gene. • The gene is activated when the repressor is removed. The gene that breaks down lactose is repressed • When lactose is added, it binds to the repressor protein. When lactose binds to the repressor, it moves away, allowing the protein to be made. Hox genes • Hox genes control the basic structure of many animals. • They are inherited from the genes of our common ancestors.