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Warm Up

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  1. Warm Up • 1. Place DNA Extraction lab into the basket located at the front • 2. Pick up your plicker card from me • 3. In your warm up notebook, write down a few sentences answering the following prompt: • If you could have the powers of one animal, what would it be and why?

  2. https://www.youtube.com/watch?v=n42PunZ3Xno • https://www.youtube.com/watch?v=dg83d4VziLk

  3. Mutations

  4. What Are Mutations? • Changes in the nucleotide sequence of DNA • May occur in somatic cells (aren’t passed to offspring) • May occur in gametes (eggs & sperm) and be passed to offspring

  5. Are Mutations Helpful or Harmful? • Mutations happen regularly • Almost all mutations are neutral • Chemicals & UV radiation cause mutations • Many mutations are repaired by enzymes

  6. Are Mutations Helpful or Harmful? • Some type of skin cancers and leukemia result from somatic mutations • Some mutations may improve an organism’s survival (beneficial)

  7. Quick Review: What is a chromosome? • A chromosome is a DNA molecule that is tightly coiled around proteins called histones, which support its structure, to form a thread-like structures.

  8. Types of Mutations

  9. Chromosome Mutations • May Involve: • Changing the structure of a chromosome • The loss or gain of part of a chromosome

  10. Chromosome Mutations • Five types exist: • Deletion • Inversion • Translocation • Nondisjunction • Duplication

  11. Deletion • Due to breakage • A piece of a chromosome is lost

  12. Inversion • Chromosome segment breaks off • Segment flips around backwards • Segment reattaches

  13. Duplication • Occurs when a gene sequence is repeated

  14. Translocation • Involves two chromosomes that are NOT homologous • Part of one chromosome is transferred to another chromosome

  15. Translocation

  16. Nondisjunction • Failure of chromosomes to separate during meiosis • Causes gamete to have too many or too few chromosomes • Disorders: • DownSyndrome – three 21st chromosomes • Turner Syndrome – single X chromosome • Klinefelter’s Syndrome – XXY chromosomes

  17. Down Syndrome • Down syndrome (DS or DNS), also known as trisomy 21, is a genetic disorder caused by the presence of all or part of a third copy of chromosome 21. It is typically associated with physical growth delays, characteristic facial features and mild to moderate intellectual disability.

  18. Turner Syndrome • A condition that affects only females, results when one of the X chromosomes (sex chromosomes) is missing or partially missing. Turner syndrome can cause a variety of medical and developmental problems, including short height, failure of the ovaries to develop and heart defects.

  19. Klinefelter’s Syndrome • A genetic disorder that affects males. • Klinefelter’s syndrome occurs when a boy is born with one or more extra X chromosomes. Most males have one Y and one X chromosome. Having extra X chromosomes can cause a male to have some physical traits unusual for males such as weaker muscles, greater height, poor coordination, less body hair, and sterility

  20. Chromosome Mutation Animation

  21. Gene Mutations • Change in the nucleotide sequence of a gene • May only involve a single nucleotide • May be due to copying errors, chemicals, viruses, etc.

  22. Types of Gene Mutations • Include: • Point Mutations • Substitutions • Insertions • Deletions • Frameshift

  23. Point Mutation • Change of a single nucleotide • Includes the deletion, insertion, or substitution of ONE nucleotide in a gene

  24. Point Mutation • Sickle Cell disease is the result of one nucleotide substitution • Occurs in the hemoglobin gene

  25. Frameshift Mutation • Inserting or deleting one or more nucleotides • Changes the “reading frame” like changing a sentence • Proteins built incorrectly

  26. Frameshift Mutation • Original: • The fat cat ate the wee rat. • Frame Shift (“a” added): • The fat caa tet hew eer at.

  27. Amino Acid Sequence Changed

  28. Gene Mutation Animation

  29. Substitution Mutation • A substitution is a mutation that exchanges one base for another (i.e., a change in a single "chemical letter" such as switching an A to a G)

  30. Insertion Mutation • The addition of one or more nucleotide base pairs into a DNA sequence

  31. Deletion Mutation • A part of a chromosome or a sequence of DNA is lost during DNA replication. • Any number of nucleotides can be deleted, from a single base to an entire piece of chromosome

  32. Normal Male 2n = 46 35

  33. Normal Female 2n = 46 36

  34. Male, Trisomy 21 (Down’s) 2n = 47 37

  35. Female Down’s Syndrome 2n = 47 38

  36. Klinefelter’s Syndrome 2n = 47 39

  37. Turner’s Syndrome 2n = 45 40

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