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PROTEIN SYNTHESIS and Mutations…

PROTEIN SYNTHESIS and Mutations…. DNA. Transcription. mRNA. Ribosome. Translation. Protein. DNA  RNA  Protein. Prokaryotic Cell. DNA  RNA  Protein. So, DNA is like a recipe… RNA is like a copy of the recipe… Protein is what is being made…the cookies!.

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PROTEIN SYNTHESIS and Mutations…

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  1. PROTEIN SYNTHESISand Mutations…

  2. DNA Transcription mRNA Ribosome Translation Protein DNA  RNA Protein Prokaryotic Cell

  3. DNA  RNA Protein So, DNA is like a recipe… RNA is like a copy of the recipe… Protein is what is being made…the cookies!

  4. What if the recipe for Grandma’s famous cookies called for 1 teaspoon of salt… But when I copied the recipe, I wrote 1 cup of salt?

  5. So, if the recipe gets changed…the cookies will get changed. It’s the same with DNA! If the original DNA is changed, the protein may be changed!

  6. Is a change in the recipe, always a bad thing? Some DNA mutations are beneficial! Remember, DNA codes for proteins that determine traits!

  7. What is a MUTATION? A change in DNA

  8. What causes MUTATIONS? They happen all the time when DNA is copied! Thankfully, DNA polymerase proofreads and fixes these changes.

  9. What causes MUTATIONS? Mutagens are things that cause mutation.

  10. Examples of mutagens… • UV light (from sun or tanning beds) • X-ray exposure • Radioactivity • Chemicals (ex: cigarette smoke)

  11. We will look at 3 types of DNA mutation. Remember, mutations are changes to DNA…that can then affect RNA…which can then affect a protein!

  12. Look at the following sentence.

  13. THE CAT ATE THE RAT THE BAT ATE THE RAT Now look at the next sentence…do you see what’s been changed? SHHHH! Don’t tell!

  14. THE CAT ATE THE RAT THE BAT ATE THE RAT

  15. 1. SUBSTITUTION • Change 1 DNA nucleotide • Can change 1 amino acid in the protein • May have no affect

  16. UGU Cysteine UGG DNA: ACA mRNA: AA: DNA: ACC mRNA: AA: DNA: ACT mRNA: AA: DNA: ACG mRNA: AA: Tryptophan UGA Stop UGC Cysteine

  17. What’s the point? • Because of the repitition of the code, sometimes you can make a substitution and it still codes for the same amino acid. Other times, it changes the amino acid. If it changes it to a “stop”, then that’s a pretty big change

  18. Look at the following sentence.

  19. THE CAT ATE THE RAT THE CAT TET HER AT Now look at the next sentence…do you see what’s been changed? SHHHH! Don’t tell!

  20. THE CAT ATE THE RAT THE CAT _TET HER AT

  21. 2. DELETION • Delete 1 or more DNA nucleotides • Shifts the nucleotides = a frameshift mutation • Changes the protein down from the mutation

  22. Look at the following sentence.

  23. THE CAT ATE THE RAT THE CAT TAT ETH ERA T Now look at the next sentence…do you see what’s been changed? SHHHH! Don’t tell!

  24. THE CAT ATE THE RAT THE CAT TAT ETH ERA T

  25. 3. INSERTION • Add 1 or more DNA nucleotides • Shifts the nucleotides = a frameshift mutation • Changes the protein down from the mutation

  26. If I spend a lot of time in the sun and the DNA in one of my skin cells gets a mutation… I may get skin cancer… But would/could I pass this to a child? Only mutations in sex cells (egg or sperm) are passed to offspring!

  27. That’s why when you have x-rays done, the technicians put a lead drape over your “reproductive zone” – they don’t want to mutate your eggs/sperm!!!

  28. Links • Sickle cell anemia: http://www.pbs.org/wgbh/evolution/library/01/2/l_012_02.html • Tay Sacs: http://www.pbs.org/wgbh/nova/programs/ht/qt/2809_qlg_03.html • Cystic Fibrosis: http://www.pbs.org/wgbh/nova/programs/ht/qt/2809_qlg_03.html • http://www.ornl.gov/sci/techresources/Human_Genome/posters/chromosome/cftr.shtml

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