1. Mutations

2. Mutations A mutations area change in the sequence of bases in DNA or RNA Mutations are essential for evolution to occur Mutations are the ultimate source of all new genetic material within a species Most have no effect at all Some are beneficial Some are harmful

3. Causes Some happen spontaneously Due to mistakes in DNA replication or in the process of transcription Others are caused by environmental factors These factors are called mutagens Germline mutations Occur in gametes Can be transmitted to offspring and will be in every cell in the offspring

4. Causes Somatic mutations Occur in other cells of the body Have little effect because these are confined to one cell and its daughter cells Can't be passed on to the offspring

5. Mutagens

6. Chromosomal Alterations Changes in the structure of the chromosome(s)

7. Chromosomal Alterations These tend to be very serious Often result in the death of the organism in which they occur If the organism survives it may be affected in multiple ways Human example - Down Syndrome A duplication mutation 3 #21 chromosomes

8. Point Mutations

9. Frameshift Mutations A deletion or insertion of one or more nucleotides that changes the reading frame of the base sequence Deletions take away nucleotides Insertions add nucleotides AUG-AAU-ACG-GUU = Start-Asp-Thre-Ala AUG-AAA-UAC-GGU-U = Start - Lys-Tyr-Gly

10. Effects of Mutations May be positive, negative, or neutral Cells also have repair mechanisms to fix errors If the damage is permanent it can't be fixed Beneficial Mutations Essential for evolution to occur Increase chances of surviving or reproducing Antibiotic resistance in bacteria Town in Italy protects from atherosclerosis

11. Harmful Mutations Proteins that don't function properly May cause genetic disorder or cancer Genetic disorder in one or a few genes Cystic fibrosis in a single gene Cancer - uncontrolled cell growth Some cancer genes can be inherited

12. Regulation of Gene Expression Not all cells make or need the same proteins Using a gene to make a protein is called gene expression This needs to be regulated When, Where and How much We will look at regulation during transcription Controlled by regulatory proteins Bind to the DNA at places called regulatory elements, which are near regions called promoters

13. Regulation of Gene Expression Regulatory proteins bind to these elements Activators or Repressors Interact with RNA polymerase which transcribes DNA into mRNA Activators promote transcription Repressors prevent or inhibit transcription

14. Regulation of Initiation

15. Prokaryotic Gene Expression It is much simpler Regulation involves something called operons A region of DNA that consists of one or more genes that encode the proteins needed for a specific function The operator is the region of the operon where regulatory proteins bind http://www.youtube.com/watch?v=oBwtxdI1zvk

16. Eukaryotic Gene Expression Very complicated Many regulatory proteins and regulatory elements involved Involved enhancers Regions of DNA that can loop back and interact with a gene's promoter

17. The TATA Box Some patterns of regulatory elements are present in all genes The TATA box is part of the promoter of most eukaryotic genes Regulatory proteins bind here When they are done binding RNA polymerase recognized the complex and goes to work transcribing the gene

18. Regulation during Development Regulation is very important when an organism is developing Genes need to be turned on and off in just the right sequence and time Homeobox genes are examples of genes that regulate development The switch on whole series of major developmental genes In insects the hox genes insure that body parts develop in the right place.

19. Homeobox Genes http://www.youtube.com/watch?v=LFG-aLidT8s

20. Gene Expression and Cancer Mutations that cause cancer generally occur in two types of regulatory genes Tumor-suppressor genes Proto-Oncogenes These genes produce regulatory proteins that control the cell cycle When these genes mutate - cells with mutations divide rapidly and without limits

21. How Cancer Develops Mutation inactivates Tumor suppressor Cells proliferate Mutation inactivates DNA repair gene Mutation of proto-oncogene creates an oncogene Mutation inactivates several more tumor suppressor genes Cancer