1. 12-4 & 5 Mutations

2. Gene Mutations Changes in one or a few nucleotides – point mutations
Occur at a single point in the DNA sequence.
Substitutions – one base changed to another.
Insertions
Deletions
Bases are inserted or removed.

3. Frameshift Mutations: insertions and deletions that shift every codon
Frameshift Mutations: insertions and deletions that shift every codon. Shift the “reading frame” of the genetic message. May change every amino acid that follows that point of the mutation.

4. Chromosomal Mutations
Changes in the number or structure of chromosomes.
May change the location of genes on chromosome.
May change the number of copies of some genes.
Deletion
Duplication
Inversion
Translocation

5. Significance of Mutations
Polyploidy – organism has extra sets of chromosomes.
When a complete set of chromosomes fails to separate during meiosis, the gametes that result may produce triploid or tetraploid organisms.
Polyploid plants are often larger and stronger than diploid plants.
Ex. Bananas, citrus fruits.

6. 12-5 Gene Regulation
How does an organism “know” whether to turn a gene on or off?
Operon – a group of genes that operate together.
Turned on to express a gene.
In e.coli – lac operon ares genes enables the bacterium to use sugar.