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Understanding Mutations: Types and Effects

This lesson introduces students to mutations, changes in the DNA sequence that can be helpful or harmful. It covers different types of mutations, such as chromosome and gene mutations, and discusses their effects. Examples and animations are used to enhance understanding.

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Understanding Mutations: Types and Effects

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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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