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Your “Do Now” 2/22

Your “Do Now” 2/22. Get out your lab from yesterday Prepare to answer questions on the back side (Make sure they are filled-in) Ask for yours back if you turned it in Going over this in 5 minutes. Your “Do Now” 2/23. Write down our 2 new learning targets:

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Your “Do Now” 2/22

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  1. Your “Do Now” 2/22 • Get out your lab from yesterday • Prepare to answer questions on the back side • (Make sure they are filled-in) • Ask for yours back if you turned it in • Going over this in 5 minutes

  2. Your “Do Now” 2/23 • Write down our 2 new learning targets: LT #2. I can explain the process of DNA replication LT #3. I can explain the causes and effects of mutations on an organism

  3. Agenda 2/23 • Notes on DNA replication • Replication activity • Get missing work in!!! • Test retakes today too

  4. Ch 12 Notes # 2 DNA Replication • DNA replication: DNA making a copy of itself • The process happens inside the cell’s nucleus

  5. Why replicate DNA? • DNA needs to replicate before cells divide. So each cell can have an exact copy of the DNA • Happens before mitosis/meiosis • Remember: 4 reasons for organisms’ cells to divide: • Growth 3. Reproduction • Healing/Repairing 4. Replacing

  6. DNA Replication: Basic Facts • We call each side of DNA a strand • DNA is double-stranded (there are 2 sides of it) • It needs to be opened before it can be replicated!

  7. DNA Replication: Basic Facts • One side of a DNA molecule will become a template for making a new strand • Template = model to copy

  8. Steps of Replication • Enzymes (chemicals) break the hydrogen bonds between bases, splitting the DNA in two (“unzipping” it)

  9. 2) Replication enzymes bring in complementary nucleotides (The matching base pair + sugar + phosphate)

  10. 3) Now there are 2 exact copies of the DNA -1/2 original strand -1/2 complementary strand

  11. We started with ____ molecule of DNA and ended with ____ • Each one is made of ____ strand of the original DNA molecule and ____ new strand

  12. Video • http://www.youtube.com/watch?v=zdDkiRw1PdU&feature=related

  13. Accuracy is important in replication! • Remember: the order of the bases in DNA is like the order of letters in a word • This means each DNA strand has to be copied exactly or a mutation (error) could occur

  14. 3 main mutations Original DNA: Mutated DNA: • Substitution • One base replaces another • Insertion • Extra bases are put into the sequence • Deletion • Bases are removed from the sequence Original DNA: Mutated DNA: Original DNA: Mutated DNA:

  15. What are some causes of mutations? • Exposure to radiation

  16. OR certain types of chemicals

  17. Mutations in a body cell are passed on to other new body cells • Example: DNA in a bone cell gets mutated, now all bone cells made by that cell have the mutation

  18. Mutations that happen in gametes get passed to offspring-Parents pass on the mutated DNA to offspring through their gametes

  19. Mutations could cause cancer (uncontrolled cell division) Example: Mutation in skin cell could lead to skin cancer

  20. Mutations can be lethal if they affect an important gene Example: Mutation in brain cell function could cause those cells not to work right •  Other times they may not affect an important gene, so they are not harmful

  21. Not all mutations are bad • Remember: mutations lead to variation, which is necessary for evolution

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