Mutations and gene regulation lecture 12-4, 12-5
Copyright Pearson Prentice Hall 12-4 Mutations What are Mutations? Changes in the genetic material.
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.
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.