This document summarizes gene regulation and mutation. It explains that gene regulation allows organisms to control which genes are transcribed in response to the environment, using operons in prokaryotes. Mutation is a change in the DNA sequence that can cause changes in proteins. There are two main types of mutations: point mutations which substitute a single nucleotide, and frameshift mutations which insert or delete nucleotides, affecting all subsequent amino acids. Mutations can be caused by environmental factors like radiation or chemicals and may be passed to offspring.

1. 12.4 Gene Regulation & Mutation- Pgs.342-349

2. Gene Regulation- ability of an organism to control which genes are transcribed in response to the environment. Prokaryotes use operons. Operons- section of DNA that contains genes for the proteins needed for a specific pathway. Ex: trp operon- tryptophan lac operon- lactose

3. Gene Regulation is crucial during development of Eukaryotes. Homeobox (Hox) genes determines the body plan of an organism.

4. Mutation- mistake or change in the DNA sequence (gene) It causes a change in the protein it codes for See table 12.3, p. 346 for a complete list.

5. Gene Mutations Point mutations – mistake with 1 nucleotide Substitution of the wrong nucleotide in place of correct one Frameshift mutations – occur when a nucleotide is either inserted or deleted , altering the codon sequence More severe than point mutations because it affects all of the amino acids in the protein

8. Causes of Mutations Mutagen – any agent that causes a change in DNA DNA polymerase sometimes adds wrong nucleotides (only 1/100,000) and goes unfixed in 1/1 billion

9. Environmental Factors x-rays ultraviolet light radioactive substances certain chemicals (asbestos, formaldehyde, benzene) high temperatures

10. Mutations in sex cells Passed on to offspring & will be present in every cell of the offspring Could result in a new trait or in a protein that does not function properly

11. Mutations in body cells Impairs the function of that cell As that cell divides, the mutation will be passed on to the new cells If it affects the genes that control division, cells can multiply rapidly-resulting in cancer

13. QUIZ Identify the following processes as transcription, replication, translation, or mutation.

14. Name the process below. mutation

15. Name the process below. DNA replication

16. Name the process below. Transcription

17. Name the process below. Translation