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Gene Action/Mutation Worksheet

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Gene Action/Mutation Worksheet

Jack Boroditsky
1994 Woodrow Wilson Collection


Introduction

Deviations from the expected chromosomal number, or mutations in the structure of the chromosome, are inherited in predictable Mendelian fashion; they often result in dead organisms or substantial changes in phenotype. Aneuploidy is the gain or loss of one or more chromosomes from the diploid amount, resulting in conditions of monosomy, trisomy, tetrasomy. Studies of monosomy (Turner Syndrome XO) and trisomic disorders (Down's Syndrome) have increased our understanding of the delicate balance that must exist in order for normal development to occur. When complete sets of chromosomes are added to the diploid number, polyploidy is created. These sets may have identical or diverse genetic origin. Large segments of the chromosome may be modified by deletions or duplications. Deletions may produce serious conditions such as Cri-du-chat Syndrome in humans. Duplications may be important as a source of redundant or unique genes, but this usually has no effect on health. Inversions and translocations, while altering the gene order along chromosomes, cause no net loss of genetic information. In an inversion, a sequence of genes is turned around. This does not affect health unless a critical gene sequence is physically disrupted. Most children with Chronic Myeloid Leukemia have a translocation or mixed up chromosome, in which the tip of chromosome 22 is attached to chromosome 9. However, this type of heterozygous combination may cause genetically abnormal gametes during meiosis, often being lethal.

A change in chromosome number or in the arrangement of a chromosome region often results in phenotypic variation or disruption of development of an organism. Such phenotypic variations are passed to offspring in a predictable manner, resulting in many interesting genetic situations.

Target Age Ability Group: Regular or Honors Biology

Student/Class Time Required:

One or two days for teacher to review concepts/terms listed below. One or two days for students to complete worksheet and review concepts. Note: based on 80 minute classes

Materials:

  • Copy of student worksheets (attached)
  • Open-book references
  • Copy of the amino acids and the DNA triplets that code for them or codon chart
  • Concepts/Key Terms:

    Teachers should review the following concepts and key terms before assigning the student worksheets:

  • DNA structure and function
  • How DNA base sequence encodes information
  • Steps in DNA replication
  • Transcription - building an RNA chain
  • Types of RNA
  • The genetic code - characteristics
  • Translation - from genetic message to protein product
  • Types of mutations - point mutations, altering number of DNA bases
  • Abnormal chromosome numbers: Aneuploidy, polyploidy
  • Deletions and duplications resulting from chromosome rearrangement - translocations, inversions
  • Outline:

    1. After the regular classroom presentations of the above concepts/key terms are completed, use these worksheets as a culminating activity.

    2. This activity may be done in pairs or as a cooperative group exercise. It is not a test! It is not a "quiet" exercise for review! It is a learning module. The teacher should encourage open discussions of the questions and answers.

    3. Students should bring as many references as necessary to facilitate the completion of the worksheets and to teach each other the concepts being discussed.

    4. Worksheets are "completed" individually (overnight) and handed in for grading. Grading can be based on the degree of completion, added illustrations and examples along with full explanations.

    Gene Action/Mutations

    Student Worksheets

    Note: Your grade on this activity will be based on the degree of completion of your answers, and added illustrations and examples along with full explanations. If you need more room, please attach sheets to the booklet.

    Part 1: Answer the following questions. [use extra attached sheets]

    Recall and Review:

    1. Define a mutation.

    2. Define mutagen. Give three examples and how they work.

    3. Define and illustrate a point mutation.

    4. Define and illustrate a frame shift mutation. Name two types of frame shift mutations.

    Challenge

    5. List up to 4 ways that DNA can mutate without affecting the phenotype.

    6. Why do you think that an excess of genetic material is usually less harmful to health than a deficit?

    Part 2: Gene Mutations

    Note: Questions #7 - #13 refer to the DNA master strand listed below:

    AATGCCAGTGGTTCGCAC

    7. Write the nitrogen base sequence of the complementary DNA strand.

    8. Write the nitrogen base sequence of the strand of M-RNA read from the master strand of DNA.

    9. Write the protein section (amino acid chain) that results from this DNA master strand. [use copy of the amino acids and the DNA triplets that code for them or M-RNA codon chart] 10. If the seventh nucleotide in the original master strand of DNA were changed from A to T, what would the resulting new M-RNA be?

    11. Write the protein fragment (amino acid chain) that results from the DNA molecule described in #10.

    12. Draw a circle around the amino acid in #11 that changed as a result of the mutation described in #10.

    13. Name the type of mutation described in #'s 10, 11 and 12.

    Note: Questions: #14 - #21 refer to the DNA master strand listed below:

    AATGCCAGTGGTTCGCAC

    14. If a `G' were added to the original master strand of DNA after the third nucleotide (T), what would the resulting mutated M-RNA look like?

    15. Write the protein fragment (amino acid chain) that results from the DNA molecule described in #14.

    16. Explain how the protein fragment (amino acid chain) in #15 has changed as a result of the mutation described in #14.

    17. Name the kind of mutation described in #14. (Be specific!)

    18. If the `G' in the fourth nucleotide position were to be cut out of the original DNA strand, what would the resulting M-RNA look like?

    19. Write the protein fragment (amino acid chain) that would result from the DNA molecule described in #18.

    20. Explain how the protein fragment (amino acid chain) in #19 has changed as a result of the mutation described in #18.

    21. Name the kind of mutation described in #18. (Be specific!)

    Note: Questions #22 - #33 refer to the DNA master strand listed below:

    AATGCCAGTGGTTCGCAC

    22. TTACGGTCACCAAGCGTG

    23. UUACGGUCACCAAGCGUG

    24. LEU, ARG, SER, PRO, SER, VAL,

    25. UUACGGACACCAAGCGUG

    26. LEU, ARG, THR, PRO, SER, VAL,

    27. Illustrate a point mutation.

    28. UUACGGUCACCCAAGCGUG

    29. LEU, ARG, SER, PRO, LYS, ARG,

    30. Add a nitrogen base in the first two coding triplets of the master DNA strand. This produces a new grouping of triplets past the change. All of the amino acids past the change are different. Illustrate and explain an insertion mutation. 31. UUACGGUACCAAGCGUG

    32. LEU, ARG, TYR, GLU, ALA,

    33. Delete a nitrogen base in the first two coding triplets of the DNA master strand. This produces a new grouping of triplets past the change. All the amino acids past the change are different. Illustrate and explain a deletion mutation.

    LETTER CHROMOSOME MUTATION DEFINITION
    _____ 34. Inversion -
    _____ 35. Polyploidy -
    _____ 36. Translocation -
    _____ 37. Trisomy -
    _____ 38. Deletion -
    _____ 39. Monosomy -
    _____ 40. Nondisjunction -